Group Title: Bioenvironmental and radiological-safety feasibility studies : Atlantic-Pacific Interoceanic canal
Title: Symposium on sea-level canal bioenvironmental studies
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Title: Symposium on sea-level canal bioenvironmental studies
Series Title: Bioenvironmental and radiological-safety feasibility studies : Atlantic-Pacific Interoceanic canal
Physical Description: Book
Language: English
Creator: Martin, William E.
Publisher: Battelle Memorial Institute
Publication Date: 1969
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Subject: Caribbean   ( lcsh )
Panama Canal
Spatial Coverage: North America -- Panama -- Panama Canal Zone
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Volume ID: VID00001
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BIOENVIRONMENTAL AND RADIOLOGICAL-SAFETY FEASIBILITY STUDIES

ATLANTIC-PACIFIC INTEROCEANIC CANAL







SYMPOSIUM ON SEA-LEVEL CANAL BIOENVIRONMENTAL STUDIES


William E. Martin, Editor






April 21, 1969






Prepared under Battelle Memorial Institute,
Columbus Laboratories, U. S. Atomic Energy Commission
Prime Contract No. AT(26-1)-171













BATTELLE MEMORIAL INSTITUTE
Columbus Laboratories
505 King Avenue
Columbus, Ohio 43201
























BIOENVIRONMENTAL AND RADIOLOGICAL-SAFETY FEASIBILITY STUDIES

ATLANTIC-PACIFIC INTEROCEANIC CANAL







SYMPOSIUM ON SEA-LEVEL CANAL BIOENVIRONMENTAL STUDIES


Presented at the 19th Annual Meeting of the American
Institute of Biological Sciences, September 4-5, 1968,
at The Ohio State University, Columbus, Ohio


William E. Martin, Editor





April 21, 1969








Prepared under Battelle Memorial Institute,
Columbus Laboratories, U. S. Atomic Energy Commission
Prime Contract No. AT(26- 1)-171







BATTELLE MEMORIAL INSTITUTE
Columbus Laboratories
505 King Avenue
Columbus, Ohio 43201
















TABLE OF CONTENTS


Paper 1. William E. Martin: Bioenvironmental Studies and the Radiological-
Safety Feasibility of Nuclear Excavation .. .

Paper 2. James R. Vogt: Radionuclide Production for the Nuclear
Excavation of an Isthmian Canal .. ... .

Paper 3. Gilbert J. Ferber and Robert J. List: Prediction of External
Gamma Dose from Nuclear Excavation of a Sea-Level Canal

Paper 4. S. V. Kaye, P. S. Rohwer, K. E. Cowser, and W. S. Snyder:
Predicting Radiation Dose Equivalents for Populations: I. Dose
Models and Methods of Application .. ......

Paper 5. P. S. Rohwer and S. V. Kaye: Predicting Radiation Dose
Equivalents for Populations: II. Results Obtained with the
Dose Models ..

Paper 6. Reina Torres de Arauz: Demographic and Dietary Data for
Human Groups Inhabiting the Eastern Region of the Republic
of Panam a . . .

Paper 7. Felix Webster McBryde and Alfredo Costales Samaniego:
Human Ecology of Northwestern Colombia (The Choco) .

Paper 8. J. F. Gamble, R. Ah Chu, J.G.A. Fiskell: Soils and
Agriculture of Eastern Panama and Northwestern Colombia.

Paper 9.. Samuel C. Snedaker and John F. Gamble: Compositional
Analysis of Selected Second-Growth Species from Lowland
Guatemala and Panama .. ..... .......


Paper 10.




Paper 11.




Paper 12.




Paper 13.




Paper 14.


W. Neill Thomasson, W. Emmett Bolch, and J. F. Gamble:
Uptake and Translocation of 134Cs, 59Fe, 85Sr, and 185W by
Banana Plants and a Coconut Plant Following Foliar Application

W. G. Blue, C. B. Ammerman, J. M. Loaiza, and
J. F. Gamble: Compositional Analyses of Soils, Forages, and
Cattle Tissues from Beef Producing Areas of Eastern Panama

William A. Goldsmith, W. Emmett Bolch, and J. F. Gamble:
The Retention of Selected Radionuclides from Dilute Solutions
by Panamanian Clays .

F. B. Golley, J. T. McGinnis, R. G. Clements, G. I. Child,
and M. J. Duever: The Structure of Tropical Forests in
Panama and Colombia ... . .

J. T. McGinnis and F. B. Golley: Elemental and Hydrologic
Budget of the Panamanian Tropical Moist Forest .


Page



. 1-1



S2-1



S3-1




. 4-1




. 5-1




S6-1



7-1


8-1


9-1


S10-1




. 11-1




. 12-1




S13-1



S14-1












TABLE OF CONTENTS
(Continued)


Page


R. L. Charnell, T. M. Zorich, and D. E. Holly: Hydrologic
Redistribution of Radionuclides Around a Nuclear-Excavated
Sea-Level Canal . .

W. L. Templeton, J. M. Dean, D. G. Watson, and L. A.
Rancitelli: Freshwater Ecological Studies in Panama and
Colombia .

Frank G. Lowman: Radionuclides of Interest in the Specific-
Activity Approach . . .


John H. Martin: Distribution of C, H, N, P, Fe, Mn, Zn, Ca,
Sr, and Sc in Plankton Samples Collected off Panama and
Colombia ........

Robert Y. Ting: Trace Element Distribution in Marine
Organisms of the Isthmian Region . ....

G. E. Raines, S. G. Bloom, and A. A. Levin: Ecological
Models Applied to Radionuclide Transfer in Tropical
Ecosystem s . . .


Paper 15.




Paper 16.


Paper 17.


Paper 18.




Paper 19.


Paper 20.


S15-1




S16-1


.17-1


S18-1


. 19-1


20-1
















SYMPOSIUM ON SEA-LEVEL CANAL BIOENVIRONMENTAL STUDIES*


William E. Martin, Editor




ABSTRACT


Battelle Memorial Institute, as a major contractor to the U. S. Atomic Energy
Commission, Nevada Operations Office, has been responsible for the technical manage-
ment of bioenvironmental studies to help judge the radiological-safety feasibility of
nuclear-excavation plans for the construction of a sea-level canal across the isthmian
region of Central America. As part of the program to predict potential external and
internal radiation doses to human populations living in the vicinity of the proposed sea-
level canal routes, extensive field studies of human, agricultural, terrestrial, fresh-
water, and marine ecology have been made by different subcontractor groups in eastern
Panama and northwestern Colombia. The results of these studies have been combined
with predictions of radionuclide production and initial fallout distribution to develop an
ecological model of radionuclide transfer through tropical food chains and other environ-
mental pathways leading to man. The model will provide calculations of the kinds and
quantities of radionuclides to be expected, during and after nuclear excavation, in the
external environments and diets of native populations living in different parts of the two
study areas, and estimates of potential radiation doses to man will be based on these
calculations. Owing to the nature of the problem and to the virtual absence of previous
ecological studies in the areas of concern, it has been necessary to make broad ecologi-
cal studies of a fundamental nature. The major purpose of this symposium is to present
the technical results of these studies. Even though the final results the estimates of
potential radiation doses to human populations will not be available for discussion at
the time of the symposium, it is hoped that the symposium will provide a convenient
forum for a general discussion of ecological studies in relation to questions pertaining
to the radiological-safety feasibility of major nuclear-construction projects.




















'The papers included in this memorandum are adapted from those presented at a symposium held during the 19th Annual AIBS
Meeting at The Ohio State University, September 4-5, 1968. The same papers are scheduled for publication in Bio Science
between February and November 1969.













1-1


PAPER 1. BIOENVIRONMENTAL STUDIES AND THE
RADIOLOGICAL-SAFETY FEASIBILITY OF NUCLEAR EXCAVATION"

William E. Martin'*




ABSTRACT


This is the first of 20 articles that will be published in BioScience to summarize
the contents of a Symposium on Sea-Level Canal Bioenvironmental Studies, which was
presented at the 19th Annual AIBS Meeting at The Ohio State University, September 3
to 7, 1968. It describes the general aspects of bioenvironmental and other studies that
have been undertaken to assess the radiological-safety feasibility of a plan to construct
a sea-level canal across the isthmian region of Central America by means of nuclear
excavation.




WHY BUILD A SEA-LEVEL CANAL?


One objective of the U.S. Atomic Energy Commission's Plowshare Program is
the development of technology for the use of nuclear explosives in massive excavation
projects. Experiments performed as part of the Plowshare Program have led to the
development of devices and techniques that minimize the production and release of radio-
active materials and the establishment of scaling factors that can be used in solving
the attendant engineering problems. The state of the art is now such that it is reason-
able to consider a variety of excavation projects in which nuclear explosives could be
used economically and safely. The most interesting project to receive serious study in
recent years is the proposed nuclear excavation of a sea-level canal connecting the
Atlantic and Pacific Oceans.

The need for a sea-level canal is indicated by the limitations of the present
Panama Canal. There are some 74 naval and commercial ships that cannot use the
present canal because they are too large to pass through the locks. Another 550 com-
mercial ships are too large to pass through the canal when they are fully loaded, and
the trend is to build even larger ships because they are more economical to operate.
An even more serious limitation is that part of the route is above sea level, and a con-
siderable volume of water is required for the operation of the locks which raise and
lower the ships in transit. The availability of water in Lake Gatun sets a limit of about
19, 000 transits per year. In recent years there have been more than 12, 000 transits
per year, and, as the number of transits increases, the average transit time will also
increase, causing expensive delays. If traffic on the canal continues to increase at the
postwar rate, the number of ships desiring to use the canal may exceed 19, 000 per year
before the turn of the century. A sea-level canal would avoid these limitations; it would
be less expensive to operate and maintain; and it would be easier to defend from possi-
ble attack.

*Studies supported by U. S. Atomic Energy Commission, Nevada Operations Office, Contract AT(26-1)-171.
**Battelle Memorial Institute, Columbus Laboratories, Columbus, Ohio.










1-2


SEA-LEVEL CANAL FEASIBILITY STUDIES


A joint study completed in 1964 by the U.S. Army Corps of Engineers, the U.S.
Atomic Energy Commission, and the Panama Canal Company considered over 30 possi-
ble routes for a sea-level canal and recommended that more detailed studies should be
made of two routes, the Sasardi-Morti route in Panama and the Atrato-Truando route
in Colombia (Figure 1-1), where nuclear excavation might be practical. The same
study indicated that it would cost approximately $2, 176, 000, 000 to convert the present
lock canal to a sea-level canal by conventional methods. The estimated cost of nuclear
excavation was $747, 000, 000 for the Sasardi-Morti route and $1, 440, 000, 000 for the
Atrato-Truando route.

In April of 1965, President Lyndon B. Johnson appointed five men* from private
life to constitute the Atlantic-Pacific Interoceanic Canal Study Commission and autho-
rized them "to make a full and complete investigation and study, including necessary
on-site surveys and considering national defense, foreign relations, intercoastal ship-
ping, interoceanic shipping, and such other matters as they may determine to be im-
portant, for the purpose of determining the feasibility of, and the most suitable site for,
the construction of a sea-level canal connecting the Atlantic and Pacific Oceans; the
best means of constructing such a canal, whether by conventional or nuclear excavation,
and the estimated cost thereof. "

It is not within the scope of this paper to discuss the entire feasibility study, but
a brief outline of the on-site surveys will place the bioenvironmental studies in better
perspective. The U.S. Army Corps of Engineers has made on-site survey studies of
topography, geology, hydrology, and hydrography to determine the engineering feasibil-
ity of the nuclear-excavation plan and the plan for conversion of the present canal to sea-
level operation by conventional methods. For the nuclear-excavation plan, detailed in-
formation concerning topography and geology is required to determine the precise
spacing, depth, and yield of nuclear devices needed to obtain the desired canal configu-
ration and to evaluate other problems such as slope stability and conventional construc-
tion requirements. Information concerning hydrology and hydrography are needed, for
example, to determine whether or not it might be necessary to divert natural drainage
in order to avoid flooding the canal during the rainy season and whether special struc-
tures might be needed to control tidal currents near the ends of the canal. Studies re-
lated to the operational-safety feasibility of the nuclear -excavation plan are considered
to be a part of the engineering-feasibility program, and the necessary on-site surveys
have been made by contractors to the U.S. Atomic Energy Commission, Nevada
Operations Office. Various contractor and consultant groups have been involved in
studies of potential seismic effects, due to ground shock, on man-made structures.
The potential effects of the long-range transmission and ducting of acoustic waves have
been studied by the Sandia Corporation. The Environmental Science Services Adminis-
tration is responsible for the meteorological studies required to predict fallout patterns
and acceptable shot days. The bioenvironmental studies required to evaluate the
radiological-safety feasibility of the nuclear-excavation plan have been made by vari-
ous subcontractor organizations under the management of Battelle Memorial Institute,
Columbus Laboratories.



*Mr. Robert B. Anderson, Chairman, Mr. Robert G. Storey, Dr. Milton S. Eisenhower, Brig. Gen. Kenneth E. Fields, Ret.,
and Mr. Raymond A. Hill.















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At the present time (September, 1968), some of these studies are still in prog-
ress. Consequently, these articles should be construed as interim reports to the sci-
entific community. The purpose of the first is simply to set the stage for those that
follow.



OBJECTIVE AND GENERAL CONCEPT OF
THE BIOENVIRONMENTAL PROGRAM


As a prime contractor to the U.S. Atomic Energy Commission, Nevada Operations
Office, Battelle Memorial Institute, Columbus Laboratories, is responsible for the
preparation of a report on which a judgment can be based concerning the radiological-
safety feasibility of the nuclear-excavation plan for sea-level canal construction.
Therefore, the principal objective of the Bioenvironmental and Radiological-Safety
Feasibility Program under Battelle-Columbus management is to estimate the potential
external and internal radiation doses to human populations living in or near the areas
most likely to be contaminated by radioactive fallout. These estimates will be compared
with the standards and guidelines established for radiological protection by the ICRP
(International Commission on Radiological Protection) and other such authorities, and
recommendations will be made concerning actions that may be required to insure the
radiological protection of project personnel and the general population. Other potential
problems of a biological nature e. g., the environmental disturbance to be expected in
areas immediately adjacent to the canal route and the possible mixing of marine biotas
previously separated by the isthmus were considered to be of lesser importance in de-
termining the feasibility of the nuclear-excavation plan, because such problems could
be anticipated even if the canal were to be constructed by conventional methods.

Details of the nuclear-excavation plan will be discussed in subsequent articles of
this series, but the basic idea is to excavate the canal in short segments. Each seg-
ment would be excavated by the simultaneous detonation of several nuclear devices
placed in a row. Most of the radioactivity produced by a given detonation would be
trapped in the rubble deposited in the channel or in the ejecta deposited along the edges
of the channel. Only a small fraction of the total would be available for wider distribu-
tion as local or long-range fallout or rainout.

The indigenous populations of the study area (Figure 1-1) are composed primarily
of Negroes, recent colonists from other parts of Panama or Colombia, Cuna Indians,
and Choco Indians. These people live in close contact with their immediate bioenviron-
ment: their subsistence culture depends primarily on shifting agriculture, hunting in
the forests, and fishing in the streams and marine habitats near their homes. If the
areas in which they live were to be contaminated by radioactive fallout, they would be
exposed not only to external radiation, but also to internal radiation due to the entry of
radionuclides into the agricultural, forest, freshwater, and marine ecosystems from
which they obtain their drinking water, their food, and the other materials essential to
their culture. Also, radioactivity could be transported to points outside the area of con-
tamination by streams or by the export of crops such as plantain or banana, or of ani-
mals such as shrimp, which abound in the Gulf of Panama.








1-5


PROCEDURE AND DATA REQUIREMENTS


The general procedure for estimating radiation doses to populations, when the
kinds and quantities of radionuclides in the environment and in the food and drinking
water consumed are known, will be discussed in the fourth article of this series. The
kinds of data required for this purpose and some indication of how they are used can be
described briefly by reference to the following general dose equation:
t2
Di = Yifi / Ci(t) Pi(t) dt(rem) .(1)
(1
tl

The subscript i indicates the dependence of dose on a particular radionuclide in a par-
ticular exposure pathway. Yifi (radionuclide yield times fraction deposited at a given
location) is the fallout input term. The dose commitment, Ci, is the dose rate from a
unit intake or external exposure unit of the radionuclide of reference. The exposure
pathway term, Pi(t), represents the quantity of a given radionuclide to which man is
exposed externally or internally.

In order to estimate the fallout input term, Yifi, in Equation (1), it is first neces-
sary to estimate the kinds and quantities of radionuclides that would be produced and
vented by each nuclear detonation. Such estimates have been provided by studies made
at the Lawrence Radiation Laboratory and at Battelle's Columbus Laboratories. The
unclassified results of these studies will be discussed in the second article of this se-
ries. Predictions of the patterns of local fallout and the potential external gamma-
exposure doses resulting from each detonation are being provided by the Environmental
Science Services Administration and will be discussed in the third article of the series.
Predictions of radionuclide production and venting are used in conjunction with fallout
predictions to evaluate Yifi (in terms of radioactivity per unit area) of critical radionu-
clides in areas corresponding to different dose or dose-rate contours of each predicted
fallout pattern. This provides an estimate of the initial geographical distribution of
those radionuclides that are most likely to account for a major part of the potential in-
ternal dose.

The dose-commitment term, Ci, has been evaluated for more than 100 radionu-
clides on the basis of radiological and biological data that are available in the reports of
the International Commission on Radiological Protection and elsewhere in the literature.
It is shown as a function of time because the interval tI to t2 may extend over a period
of years, and some of the parameters influencing Ci (assimilation and elimination rates,
organ size, etc. ) may be age dependent.

The pathway of exposure, Pi(t), is the term about which the least is known at the
present time. The most important pathways of external exposure are exposure to fall-
out material on land and forest canopies. The important pathways of internal exposure
are the ingestion of contaminated water and foods, including agricultural products, ter-
restrial birds and mammals taken from the forests, and fish or other aquatic organisms
taken from freshwater streams, estuaries, or the open seas.

In reference to internal dose calculations, Pi(t) represents the quantity of a given
radionuclide reaching man by a particular environmental or biological pathway as a
function of time. A given pathway may, of course, carry many radionuclides, and a


I










1-6


given radionuclide may enter the diet by many different pathways. Evaluation of the im-
portant pathways for the critical radionuclides will, in conjunction with dietary data,
provide a basis for estimating, for a given population or individual at a given place and
time interval, the total intake of potentially critical radionuclides and the consequent
dose equivalents to critical organs.

Field studies in the areas of human, agricultural, forest, freshwater, and marine
ecology and studies of hydrological and ecological transfer processes were undertaken
by Battelle and various subcontractor groups to acquire the data and to develop the mod-
els needed to evaluate the major pathway terms for the potentially critical radionuclides.
These studies will be reviewed in subsequent articles.

Human ecology studies in Panama and Colombia have provided information con-
cerning the demography, the dietary habits, and the subsistence economy of the indig-
enous populations. Studies of agricultural, forest, freshwater, and marine ecology and
of hydrological modeling have provided data concerning the natural distribution and
transfer pathways of essential elements and of certain trace elements corresponding to
potentially critical radionuclides. Data concerning the biogeochemistry of a few poten-
tially important elements such as tungsten and cerium are still meager because these
elements are not abundant in the soils, waters, and foodstuffs of the study area. The
last paper of the series will describe the ecological-modeling procedures developed to
obtain estimates of potential radionuclide intakes and potential radiation doses associ-
ated with various conditions of environmental contamination and modes of human
exposure.

These studies have served to increase our knowledge and understanding of the
principal ecosystems of eastern Panama and northwestern Colombia. They have also
greatly clarified the interrelation of indigenous human populations and the bioenviron-
ments on which they depend for subsistence, but they have not provided all the informa-
tion required to estimate potential radiation doses by means of the most realistic meth-
ods available. The reasons for this will be made obvious in the papers that follow, and
it will also be made clear that the alternative methods available at this time are quite
conservative in that they lead to dose estimates that are higher than those that would be
expected on the basis of ameliorating factors which are known to exist but which cannot,
at this time, be quantified. In view of the uncertainties involved in estimating radionu-
clide production, fallout deposition, and radionuclide redistribution and transfer through
the pathways leading to man, an element of conservatism is desirable to provide a wider
margin of radiological safety.

The ultimate feasibility of nuclear canal construction and the decision whether to
proceed with the nuclear-excavation plan or to take another course of action may be in-
fluenced by a great many considerations that have nothing to do with radiological safety
or bioenvironmental factors. If a decision is made to proceed with the nuclear-
excavation plan, a few years will pass before the construction actually begins. One may
assume that this time will be available for further study of critical problems related to
the assessment of radiological safety and of other ecological problems that may con-
tribute to the total biological cost of the project. We are attempting to provide a sound
basis for judging one aspect of the total problem the radiological-safety feasibility of
the nuclear-excavation plan; but among the significant results of the initial studies should
be included the identification and definition of potentially important problems about which
more information is needed.










2-1


PAPER 2. RADIONUCLIDE PRODUCTION FOR
THE NUCLEAR EXCAVATION OF AN ISTHMIAN CANAL"

James R. Vogt**



ABSTRACT



The preliminary concept for the construction of a sea-level canal using nuclear
explosives is discussed with reference to the number and sizes of nuclear devices that
may be required and the characteristics of these devices. The factors affecting radio-
nuclide production and distribution are described along with some recent nuclear experi-
ments conducted by the U.S. Atomic Energy Commission to provide technical data on
cratering mechanisms and special emplacement techniques which could minimize the re-
lease of radioactivity to the atmosphere. The quantities of radioactivities which would
be released into the cloud and local fallout for major excavation projects, using nuclear
technology which can reasonably be expected to be available sometime in the future, are
presented for a representative set of radionuclides.



INTRODUCTION


The Atlantic-Pacific Interoceanic Canal Study Commission is currently considering
three alignments in the Darien region of eastern Panama and one alignment in the Choco
region in the northwest corner of Colombia for nuclear excavation of a sea-level canal.
The Panamanian alignments called Routes 17A, 17B, and 17C all originate near
Sasardi Point and all cross the continental divide at the same point. Routes 17A and 17B
exit in Boca Grande of San Miguel Bay, while 17C exits in more open water in San
Miguel Bay. The Colombian alignment called Route 25A originates in Candelaria
Bay of the Gulf of Uraba and exits in Humboldt Bay on the Pacific side. The northern
part of Route 25A would be excavated by conventional means. The nuclear-detonation
data for Routes 17A and 25A are given in Table 2-1.



NUCLEAR DEVICE CHARACTERISTICS


Present plans for the nuclear excavation of a sea-level isthmian canal are based
on a family of nuclear explosives which can reasonably be expected to be available in
the future. These devices have yields of 0. 1, 0. 2, 0. 5, 1. 0, 2. 0, 5. 0, and 10. O0 mega-
tons (1 megaton is equivalent to 1015 calories or 1. 2 billion kilowatt-hours). The U.S.
Atomic Energy Commission is conducting studies and experiments on factors that will
minimize the radioactivity released to the atmosphere from a nuclear cratering explo-
sion. Among these factors are neutron shielding, special emplacement techniques,

*Studies supported by U. S. Atomic Energy Commission, Nevada Operations Office, Contract AT(26-1)-171.
**Battelle Memorial Institute, Columbus Laboratories, Columbus, Ohio.










2-2


scavenging during the cratering process, and the utilization of minimum-fission explos-
ives. Two such experiments were conducted as part of the underground nuclear-testing
program during 1967 at the AEC's Nevada Test Site. One, the Switch event, was an ex-
periment designed to keep fission product and induced activity to a minimum. Another,
the Marvel event, was part of the effort to develop special emplacement techniques to
entrap underground greater amounts of the radioactivity produced in cratering explo-
sions. During 1968 the AEC conducted two nuclear cratering explosions at the Nevada
Test Site to obtain new data on cratering mechanisms and to refine existing models and
atmospheric-diffusion predictions relating to the released radioactivity. The first of
these, the Cabriolet event, was a 2. 5-kiloton cratering experiment in rhyolite which
produced a crater about 125 feet deep and 400 feet in diameter. The second event,
Buggy, was the first nuclear row-charge experiment to be conducted by the United
States. This experiment consisted of the simultaneous detonation of a row of five
1-kiloton nuclear explosives, and produced a ditch about 80 feet deep, 300 feet wide,
and 900 feet long. These experiments are part of a continuing program to develop the
technology necessary to use nuclear explosions for excavation projects such as the pro-
posed isthmian canal. Characteristics of the family of nuclear explosives proposed for
construction of a sea-level canal are given in Table 2-1.



FACTORS AFFECTING RADIONUCLIDE PRODUCTION


In nuclear devices utilizing only the fission process, the potential radiation dose
is due almost entirely to fission products. However, in devices having low fission-to-
fusion ratios other sources of radionuclides assume a greater relative significance. In
addition to fission products, the following groups of radionuclides will be produced by a
thermonuclear explosion:

(1) Residual fissionable or fusionable materials which are not consumed
prior to the disassembly phase of the detonation.

(2) Thermonuclear-reaction products such as tritium and 7Be.

(3) Induced activities from the reactions of neutrons from the fission and
fusion processes with device materials. (Examples of these are 54Mn,
55Mn, 55Fe, 59Fe, 185, 187W, and 203pb.)

(4) Induced activities from the reactions of those neutrons escaping from
the device canister with the grout and rock surrounding the device.
(Examples of these are 24Na, 32p, 45Ca, 56Mn, 55Fe, and 59Fe.)

While decreasing the fission-to-fusion ratio lowers the amount of fission products
produced by a given device, it also tends to increase the total neutron yield, since about
2. 5 moles of neutrons are produced per kiloton of fusion, whereas only 0. 5 mole of
neutrons is produced per kiloton of fission. Superficially, this would tend to indicate a
large increase in the device- and rock-activation products. It should be emphasized,
however, that these are the total numbers of neutrons produced. Some of these will
react during the fission or fusion process, others will be removed due to selfshielding
in the thermonuclear fuel, and still others will be attenuated and/or absorbed by mate-
rials within the device, by the device canister, and by materials used specifically for


neutron shielding. As a result of these processes, only a small fraction of the neutrons










2-3


TABLE 2-1. DETONATION DATA FOR
ROUTES 17A AND 25A(a)


Number of Devices

Total Yield, megatons

Yield of Largest Detona-
tion, megatons

Largest Device, megatons

Number of Detonations

Length, miles


Route
17A 25A
437 223

274.8 245. 1


30. 0

10.0

22

48.5


30. 0

10. 0

19

39.3


(a) Assuming a 1000 x 60-foot navigational channel.


TABLE 2-2.


CHARACTERISTICS OF PROPOSED FAMILY OF NUCLEAR EXPLOSIVES


Total Emplacement Projected
Device Canister Canister Canister Hole Charge for
Yield, Diameter, Length, Weight, Diameter, Explosive and
kilotons (a) inches feet pounds inches Firing Services

100 34 10 7,500 36 $ 460,000

200 34 15 10,000 36 490,000

500 45 15 17,000 54 540,000

1,000 45 15 17,000 54 570,000

2,000 45 20 23,000 54 600,000

5,000 45 35 40,000 54 1,000,000

10,000 45 60 70,000 54 1, 000,000

(a) 1 kiloton = 10-3 megaton.










2-4


produced will interact with the grout and rock surrounding the device, and only a small
fraction of these will have energies near 14 MeV the energy of the neutrons produced
by the T(d, n)He4 thermonuclear reaction. Therefore, the predominant nuclear reaction
in the soil is radiative capture. Fast-neutron reactions, such as the (n, c), (n, 2n), and
(n,p) reactions, are of less importance in the production of neutron-induced activities
in the rock.



RELEASE OF RADIOACTIVE DEBRIS


For most of the radionuclides released during a cratering detonation, a large frac-
tion of the activity will be distributed in the fallback and throwout material. The frac-
tion of the radioactivity that is distributed in the throwout and fallback is a function of
the rock type, the depth of burial, the rock's water content, and the parent-daughter
history of the radionuclide. Of the vented material, most will be deposited as local
fallout within a few hours after detonation; the actual time will depend on cloud height,
wind shear, and mean wind speed, particularly in the top 60 to 70 percent of the cloud.
A small fraction of the total activity can be classed as long-range or tropospheric
fallout. Precipitation will decrease the fraction appearing as long-range fallout and will
tend to bring down the local fallout more rapidly, resulting in higher area
concentrations.

The following "planning information" statement has been released by the AEC:
"In order to plan for major excavation projects, the following factors relative to release
of radioactive debris should be taken into account: The amount of radioactivity airborne
in the cloud and in the fallout is minimized by scavenging during the venting process, by
special emplacement techniques, by utilizing minimum fission explosives, and by em-
ploying extensive neutron shielding. Based on reasonable assumptions about these fac-
tors, the following information can be used in planning for cratering events of useful
magnitude. For each individual nuclear explosive detonated, the sum of fission prod-
ucts airborne in the radioactive cloud and in the fallout can be expected to be as low as
the equivalent of 20 tons. The tritium release may be less than 20 kilocuries per kilo-
ton of total yield. The sum of activation products airborne in the radioactive cloud and
in the fallout may be expected to be as low as the amounts shown in Table 2-3. "

The above AEC statement indicates that for planning purposes the sum of the fission
products (due to the factors given in the statement) in the cloud and fallout may be as
low as the equivalent of 20 tons for each device. Using tabulations of fission-product
production per kiloton of fission and dividing by 50, one can arrive at the tentative list
of fission products given in Table 2-4.

A number of the radionuclides in Tables 2-3 and 2-4 have relatively short half-
lives. Because of this, in most cases they are of importance primarily for the case of
short-term external exposure. Radionuclides having relatively long half-lives, such as
90Sr and 137Cs, are primarily of importance from the standpoint of long-term internal-
radiation exposure. However, as can be seen from the tables, these long-lived radio-
nuclides are released in amounts which are small compared to the other radionuclides.









2-5 and 2-6


TABLE 2-4.


REPRESENTATIVE SET OF FISSION
PRODUCTS 1 HOUR AFTER
DETONATION TIME

Total in Cloud and Fallout


Nuclide Half-Life Kilocuries Per Device

90Sr 28 years 0. 001
137Cs 30 years 0. 004
106Ru 1 year 0. 08

89Sr 50 days 0.2
144Ce 284 days 0. 07

91y 59 days 0. 007
95Zr 65 days 0.4
103Ru 40 days 0. 9

1311 8. 1 days 1. 0
141Ce 33 days 0. 09


TABLE 2-3. REPRESENTATIVE SET OF INDUCED RADIOACTIVITIES
AT DETONATION TIME
Total in Cloud and Fallout


Nuclide Production in Kilocuries Per
Nuclide Half-Life 0. 1 Megaton 1 Megaton 10 Megatons

24Na 15. 0 hours 200 800 2000
32p 14.3 days 0. 1 0.4 0.8

45Ca 165 days 0.01 0. 03 0.06
54Mn 303 days 0. 1 0.3 0.7
56Mn 2. 58 hours 600 2000 5000
55Fe 2. 70 years 0.04 0. 15 0.3

59Fe 45 days 0.04 0. 15 0.3
185W 74 days 6 10 14
187W 24 hours 300 500 700

Other 15 20 40













3-1


PAPER 3. PREDICTION OF EXTERNAL GAMMA DOSE
FROM NUCLEAR EXCAVATION OF A SEA-LEVEL CANAL"

Gilbert J. Ferber"
Robert J. List


ABSTRACT


The principal factors involved in estimating the external gamma dose from
nuclear excavations are discussed with particular emphasis on the limitations of our
present knowledge. Some preliminary fallout estimates are presented for the
proposed nuclear excavation of a sea-level canal in Panama (Route 17). Despite the
many uncertainties in dose prediction, the safety problems, with respect to external
gamma doses, appear to be manageable by evacuating a preselected exclusion area
and restricting the nuclear detonations to weather situations which would confine the
local fallout to that area. Preliminary analysis of weather data from Route 17
indicates that favorable weather conditions occur with sufficient frequency to carry
out this concept.



INTRODUCTION



Nuclear excavation of a sea-level canal (USAEC 1964, Vortman 1964) in
either Panama or Colombia would require the use of several hundred nuclear
devices with a total megatonnage probably exceeding the combined power of all
United States nuclear tests to date. The channel would be blasted in sections with
about 20 separate detonations, each comprised of a row of from 4 to perhaps 50
nuclear devices which would be detonated simultaneously.

Most of the radioactivity produced by each detonation will be buried with the
rubble in the crater and on the crater lip. The remaining activity will be
incorporated in the debris cloud produced by the explosion. As the cloud is carried
away from the detonation site by the winds, the radioactive debris gradually settles
to the ground to form the fallout pattern. Most of the radioactivity in the cloud is
associated with the larger particles which are deposited in a matter of hours. A
small fraction remains airborne, in gaseous form or attached to very small
particles, for days, weeks, or even longer. This fraction may be carried far from
the detonation site before being deposited, primarily by precipitation.


*Studies supported by U. S. Atomic Energy Commission, Nevada Operations Office, Contract SF 54-351.
**Air Resources Laboratories, Environmental Science Services Administration.











3-2


An appraisal of the potential radiological hazard to man and his environment
requires quantitative estimates of both the external gamma dose and the internal
dose due to ingestion or inhalation of radioactive matter. This paper deals only with
the estimation of external gamma doses associated with the local fallout.


BASIS FOR FALLOUT PREDICTION


Quantitative fallout prediction usually begins with a model of the radioactive
cloud and proceeds to the calculation of atmospheric transport and deposition of the
nuclear debris. In the case of nuclear excavation, the size and shape of the clouds,
and the amount and distribution of radioactivity within them depend on:

(1) The total yield and fission yield of the nuclear detonations

(2) The types and amounts of radioactivities induced in the nuclear-device
materials and in the surrounding rock or soil

(3) The depth of burial of the nuclear devices

(4) The medium being excavated.

The nuclear yields and burial depths of the explosives must be selected to
produce the desired canal dimensions. This selection then determines the amount
of radioactivity produced and the fraction of the total activity which will be vented
into the atmosphere.

The nuclear cloud produced by a cratering detonation typically consists of a
central column, or "main cloud", rising above a doughnut shaped "base surge" which
rolls outward from the crater. This is illustrated by the Sedan cloud in Figure 3-1.
Sedan was a cratering experiment (Nordyke and Williamson 1965) conducted in the
Nevada Test Site in 1962 with a 100-kiloton device emplaced at a depth of 630 feet.
This is the largest cratering detonation conducted to date. The main cloud rose to
a height of 12, 000 feet, the base surge to about 4000 feet.

At present, a scaling procedure based on the Sedan cloud dimensions is used
to predict the canal-cloud dimensions. Most significant from the standpoint of the
feasibility studies is the height to which the cloud rises. In general, the higher the
cloud, the more difficult it becomes to confine the fallout to a desired sector.
Scaling from the Sedan cloud, it is estimated that the cloud tops for the various canal
detonations would range from 20, 000 feet to about 40, 000 feet. While the reliability
of the present scaling procedure is as yet unproven, particularly for application to
simultaneous detonation of rows with as many as 50 charges, it is reasonably certain
that the base of the stratosphere, which is at about 55, 000 feet in the equatorial zone,
represents an upper limit to the growth of clouds from the largest detonations under
consideration. Cloud-height predictions will be improved as more detailed
geological data from the proposed routes and data from future nuclear excavation
experiments become available.











3-3









Ilk 3





k
'4 .. ', ** .4 .- '"













FIGURE 3-1. NUCLEAR CLOUD PRODUCED BY
SEDAN CRATERING EXPERIMENT


Next, we will consider the radioactivity which would be deposited from the
debris clouds. In order to minimize the production of radioactive material, the
nuclear explosives designed for excavation applications derive only a small part of
their energy from nuclear fission; most of the energy comes from the fusion process.
However, the fusion reaction produces large quantities of neutrons which induce
radioactivity in the material of the explosive package and the surrounding medium so
that special shielding must be used to reduce the neutron flux. The net result of this
design is a great reduction in the amount of radioactivity per megaton of total yield.
The fallout will be composed primarily of induced radioactivity rather than fission
products.

The fraction of the total radioactivity produced which is deposited as local
fallout depends, like the cloud development, on the nuclear yield and burial depth of
the nuclear devices and on the type of rock being excavated. The maximum fallout
fraction would be 70 to 80 percent for very shallow burial depths. As the depth of the
explosion point is increased, the fallout fraction gradually decreases, and more and
more of the radioactive debris is trapped in the crater rubble. Experiments indicate
that excavation in dry, hard rock will result in much less fallout than comparable
excavation in alluvium or tuff.

The rock types found along the proposed canal routes in Panama and Colombia
include basalt, tuff, limestone, and clay-shale. Obviously we are not yet able to
make precise predictions of fallout fractions for such a variety of media; however, we
can estimate the probable range of values which would occur.
~dKwIL






SEDAN RATERNG EXPRIMEN

Nex, we il cnsderth rdiactviy hih wul b dposte fomth
debrisclouds In orer tominimi ze th prodution f radiactivemateril, th
nuclar eplosves esiged fr exavaton ppliatios deive nly smal pat o

thirenrg fomnuler isin;mot f heenrg cms ro te usonprces











3-4


We expect that fallout fractions would range from about 5 percent for dry, hard
rock to perhaps 30 percent in the weak, wet shales. In light of the present uncer-
tainties an intermediate value of 15 percent has been used as the fallout fraction for
external-gamma-dose calculations for all the canal detonations. Although the actual
fraction for individual detonations may be expected to differ from this value by as
much as a factor of three, the aggregate fraction from all detonations should be
within a factor of two of that estimated. Further refinement of the fallout estimates
requires additional nuclear-excavation experiments, including single and row charges
in a variety of rock media. Also, theoretical work now in progress should lead to a
better understanding of venting mechanisms.

The limited data from cloud and fallout sampling programs in past nuclear
cratering experiments have been used to develop preliminary models of the
distribution of the radioactivity with respect to particle size and height in the nuclear
cloud. The present model places 60 percent of the activity in the base surge cloud
and 40 percent in the main cloud. The distribution with respect to particle size was
chosen to reproduce the rate of fallout deposition observed in past detonations. The
fraction of the fallout deposited each hour after an explosion, when adjusted for
differences in cloud height, is approximately the same for each cratering detonation
conducted to date. The average fraction deposited per hour is shown in Table 3-1 for
a cloud rising to 12, 000 feet. The time required for the fallout to be deposited is
proportional to the cloud height. For example, with a 24, 000-foot cloud 66 percent
would be deposited in the first hour, 17 percent in the second hour, etc. About
90 percent of the local fallout from the largest canal detonations would be deposited
within 6 hours. The fraction of the vented radioactivity remaining airborne beyond
the local fallout area cannot yet be reliably predicted. It appears to be less than
the amount deposited in the local fallout, perhaps much less. Note that Table 3-1
gives the fraction of the local fallout deposited, not the fraction of the total vented
radioactivity.


TABLE 3-1. RATE OF DEPOSITION OF
LOCAL FALLOUT FOR
12, 000-FOOT CLOUD TOP




Time Interval, Fraction of Local
hours Fallout Deposited

0-0.5 0.66
0.5-1.0 0.17
1-2 0.07
2-3 0.04
3-4 0.02
4-5 0.01
5-6 0.009
6-7 0.007
7-8 0.006










3-5


Having arrived at a model of the nuclear cloud and the distribution of activity
within it, the calculation of transport and deposition of the debris is relatively
straightforward. The nuclear cloud is subdivided into a number of horizontal slices
and the fallout particles in each slice are grouped into discrete size ranges. Each
particle-size range from each slice in the cloud is treated as a disc which is
transported horizontally by the winds as it falls to the ground by gravitational settling.
The transport calculation requires measurements or forecasts of the winds at all
altitudes from the ground to the top of the nuclear cloud. Since the total activity in
the cloud and the fraction contained in each disc is specified, the concentration of
activity at any point on the ground can be readily calculated by summing the
contributions from all discs landing at the point. The gamma-dose rate at any time
and the total gamma dose is calculated from the concentration and the decay rate of
the radioactivity.

The potential hazards which might develop as a result of rain scavenging of
airborne nuclear debris, possibly remote from the canal site, must be considered
in the canal-feasibility studies. Portions of the nuclear clouds are likely to drift
over areas where rain showers are occurring since rainfall is frequent in this region
during most of the year. The meteorology program includes a study of precipitation
patterns in the route areas by means of rain gages and weather-surveillance radars.
If necessary, meteorological restrictions could be placed on the excavation schedule
which would minimize the probability of rain scavenging debris over populated areas.


PRELIMINARY FALLOUT STUDIES FOR ROUTE 17


The present concept for nuclear excavation of a sea-level canal envisions the
establishment of an exclusion area which would be evacuated or controlled during the
excavation phase. Detonations would be conducted only on days when the winds would
confine the local fallout pattern to the exclusion area (Figures 3-2 and 3-3).

Four weather stations were established to measure winds and precipitation in
the vicinity of Route 17 in Panama and Route 25 in Colombia. One weather station
is still in operation near the Pacific end of the Colombian route.

A sample detonation schedule has been developed from the days on which
favorable winds were observed and fallout calculations were made using the actual
winds on the selected dates. Figure 3-2 shows an exclusion area being considered
for Route 17 and an estimate of the total fallout pattern from all the detonations on
the route. The contours indicate the lifetime dose in roentgens (external gamma),
from deposited fallout, which would be received by persons residing in the area
continuously during and after the period of nuclear excavation. This dose pattern is
purely hypothetical since people would be evacuated during the nuclear-excavation
phase. It is intended only as an indication of the expected levels of contamination.
For comparison, when the United States was engaged in atmospheric nuclear tests
at the Nevada Test Site, the maximum permissible lifetime dose to the surrounding
population was set at 3.9 roentgens. The shaded area in Figure 3-2 indicates where
this dose would be exceeded.










3-6


FIGURE 3-2. TOTAL
ESTIMATED LIFE-
TIME DOSE
(ROETEGENS-
WHOLE BODY
GAMMA) FROM
ROUTE 17 NUCLEAR
EXCAVATION






















FIGURE 3-3. TOTAL
ESTIMATED LIFE-
TIME DOSE
(ROETEGENS-
WHOLE BODY
GAMMA) BEGINNING
ONE MONTH AFTER
THE LAST
DETONATION










3-7


Figure 3-3 shows a lifetime-dose pattern when people reenter the exclusion
area 1 month after the last detonation. Due to radioactive decay during the
construction period, there is now only a small area where a lifetime dose of
3. 0 roentgens is exceeded.

A significant factor in the determination of the feasibility of nuclear excavation
is the frequency of occurrence of favorable winds, that is, winds which would confine
the fallout deposition to the exclusion area. The exclusion area under consideration
provides a fallout sector toward the southwest, and another sector toward the north
in order to avoid fallout toward the east or west. Toward the east, fallout would cross
the border into Colombia while toward the west, it would affect the more heavily
populated areas of Panama.

Our study of the winds over Panama indicates a relatively high frequency of
favorable winds from October through May and unfavorable winds from June through
September. Figure 3-4 shows the number of days per month with favorable winds for a
typical detonation on Route 17. The statistics are based on wind data from the Pidiaque
weather station which was in operation from August, 1966, through December, 1967.
A day was considered acceptable for detonation if two consecutive wind soundings (taken
at 6-hour intervals) indicated that the fallout would be confined to the sectors from 180
to 255 degrees (Gulf of Panama) and 335 to 055 degrees (Caribbean Sea).




z20- -
z
0


2 15
U. 4 BL.... .
o. fo clou o o 20,000 FT.---
J j .. 30,000 FT.--


....... .....
L 5 .. ...:::::: ::: 50,000 FT.- : : : ::



AUG SEP OCT NOV DEC JAN FEB MAR APR MAY JUN JUL AUG SEP OCT NOV DEC
1966 ---1967 -



FIGURE 3-4. NUMBER OF ACCEPTABLE FIRING DAYS
AS A FUNCTION OF CLOUD HEIGHT FOR
A ROUTE DETONATION (FALLOUT ONLY)



There are very few acceptable days for detonations from June through
September, regardless of the cloud height. During the rest of the year there is an
average of 15 acceptable days per month for a cloud top of 20,000 feet, about 10 days










3-8


per month for a cloud top of 30, 000 feet, about 7 days for a 40, 000-foot cloud, and
about 4 days for a 50, 000-foot cloud. The number of acceptable days will be further
reduced due to air-blast restrictions since air-blast propagation is dependent on
meteorological factors at higher altitudes. Problems due to rain scavenging may
also reduce the number of acceptable days. On the other hand, as more is learned
about fallout from nuclear cratering experiments, we may find that detonations could
be conducted on many days which are now classified as unfavorable.


CONCLUSIONS


In spite of the present uncertainties in fallout prediction, it appears that from
the standpoint of external gamma dose, the safety problems are manageable. In
general, the less certain we are about the fallout from a particular nuclear event,
the more stringent must be the meteorological controls to ensure the safety of the
surrounding population. If the nuclear detonations can be restricted to weather
situations that confine almost all the local fallout to a preselected exclusion area,
the uncertainty in dose predictions is not critical. Preliminary analysis of the
weather data obtained from Route 17 in Panama indicates that favorable winds occur
with sufficient frequency to permit the nuclear excavations to be conducted under such
restraints. However, a more detailed analysis of the combined effects of fallout,
rain scavenging and air blast must be completed before firm conclusions can be
drawn. This analysis is in progress along with similar studies for Route 25 in
Colombia.

A meteorological program will be required after the feasibility study to
develop the ability to forecast favorable weather with the necessary precision. As
more is learned through theoretical studies and nuclear excavation experiments
carried out under the Plowshare program, confidence in fallout predictions should
increase and the necessary meteorological controls may become less stringent than
those assumed in the present study.


REFERENCES


Nordyke, M. D. and M. M. Williamson. August 1965. The Sedan Event. Lawrence
Radiation Laboratory, Livermore, Calif. PNE-242F.

Vortman, L. J. February 1964. Construction of a Sea-Level Transisthmian Canal
Using Nuclear Explosives. Sandia Corporation, Alburquerque, New Mexico.
SC-4929 (RR).

U. S. Atomic Energy Commission. April 1964. Engineering with Nuclear Explosives
(Proceedings of the Third Plowshare Symposium). TID-7695.










4-1


PAPER 4. PREDICTING RADIATION DOSE EQUIVALENTS FOR POPULATIONS:
I. DOSE MODELS AND METHODS OF APPLICATION"

S. V. Kaye, P. S. Rohwer, K. E. Cowser, and W. S. Snyder..



ABSTRACT



Models have been developed and programmed to estimate potential radiation doses
to populations in various hypothetical exposure situations under evaluation as part of
the feasibility study for excavating a sea-level canal with nuclear devices. Input data
may be held constant or varied as a function of several variables including age. A
method is also described for systematically identifying the radionuclides in given
exposure situations which are likely to deliver most of the dose.



INTRODUCTION



It is anticipated that the nuclear explosions proposed for excavation of a sea-level
canal may result in some finite radiation exposure to human populations. The methods
of estimating this radiation exposure must be sufficiently accurate so that a realistic
assessment of radiological safety may be made, thus permitting plans to insure the
maximum safety of all members of the population to be carried out with confidence.
Calculation of dose equivalents that may be received by the general population re-
quires biological data for adults, children of all ages, and even for fetuses. Age-
dependent considerations make the problem more complex than when only the param-
eters characterizing "standard man" are used; however, when parameters that
change with age are used, the resulting dose estimates may be helpful to identify the
critical population group. This segment of the population probably would receive the
highest dose equivalents in the hypothetical situation and thus may impose restrictive
conditions on the operation.

When the radiation source is exterior to the body, there is no dose commitment
for the future. That is, the dose ceases when the person being irradiated leaves the
radiation field, washes radioactivity from the surface of his skin, or removes his
contaminated clothing. The situation is different when the source is within the body
because the person being exposed has a finite dose commitment from intake of certain
radionuclides which may continue throughout the remainder of his life. Remedial action
is simple in the case of external radiation either remove the source or the person
being exposed. For the excavation of a canal with nuclear explosives, the obvious action

*Prepared for Battelle Memorial Institute, Columbus Laboratories, under U. S. Atomic Energy Commission, Nevada Operations
Office, Contract AT(26-1)-171.
**Health Physics Division, Oak Ridge National Laboratory (operated by Union Carbide Corporation for the U. S. Atomic Energy
Commission).
**Dose Equivalent (rem) = Absorbed dose (rad) x modifying factors. For the sake of convenience, "dose" is often used inter-
changeably with "dose equivalent" in this paper.
*":*"Standard man" is a notional adult designed to represent a typical or average adult who is exposed occupationally. See
ICRP Publication 2(1959) for details.










4-2

would be to evacuate the people from the affected environment. When the environmental
contamination has decayed or been reduced to acceptable levels by other processes, the
people may return.



ESSENTIAL INFORMATION FOR DEVELOPING MODELS
FOR DOSE ESTIMATION


The information essential for developing a model to estimate dose to a population
may be divided into five categories: (1) inventory of radionuclides produced and frac-
tions released to the environment, (2) environmental dilution or concentration factors,
(3) intake and/or exposure-time factors, (4) biological parameters and habits charac-
terizing the populations being exposed, and (5) dose-estimation equations.

Most data on production and venting for nuclear cratering devices which may be
used to excavate a canal are based on technology developed at the National Testing Site
in Nevada. This experience also provides much of the nuclear-engineering data for the
feasibility study for a sea-level canal. A nuclear cratering detonation produces an
inventory of radionuclides composed of fission products, residual fissionable materials,
fusion products, device activation products, and soil and rock activation products.
This radionuclide inventory, then, is the source of potential radiation exposure when
some of it is vented to the atmosphere or redistributed in the environment by ground
water, so that radioactivity enters a food chain leading to man.

When radioactivity is released to the environment, it moves through pathways
which might eventually lead to man. When attempting to estimate radiation doses from
proposed Plowshare applications, probably one of the most formidable challenges is
anticipating for a given application, in a given environment, that fraction of the inven-
tory which will lead to human exposure. Our calculations utilize the best available
estimates of all five categories of information listed above.

For the purposes of this feasibility study, we believe that most, if not all, of the
possible radiation exposures to humans from the proposed construction will be received
via the following five modes of exposure: Inhalation and ingestion are two principal
modes of exposure which result in internal exposure, i.e., the source of radioactivity
enters the body. The remaining three modes result in external exposure from submer-
sion in the over-passing radioactive cloud, submersion in contaminated water, and
exposure to a contaminated landscape. Internal radiation doses are estimated with a
computer code called INREM, and the external radiation doses are calculated with a
computer code known as EXREM. The estimates of radiation dose which these codes
produce cannot be any better than the input information on which they are based. The
principal objective of the feasibility study is to obtain the best possible inputs for
estimating potential radiation doses and to calculate the desired estimates of dose.

Techniques of systems analysis are being used by Battelle Memorial Institute to
estimate the net result of the numerous environmental dilution or concentration factors
affecting transfer of each critical radionuclide through the exposure pathways in the
canal environment. These techniques are designed to identify critical pathways and to


predict eventual concentrations of radioactivity in food consumed by man. Such a systems
analysis approach, based on a coupled-compartment model and utilizing a computerized










4-3


sensitivity analysis of transfer coefficients, has been discussed and illustrated by Kaye
and Ball (in press) for a hypothetical banana plantation. The output from the systems
analysis program is the input in terms of daily intake (pCi) for the INREM code. In
order to compute the dose equivalents for different age groups, other input information
is included such as organ dimensions and masses, biological half-times, and assimila-
tion fractions (all as a function of age). The following section describes our attempt to
include these age dependent parameters in internal dosimetry models.



A GENERALIZED MODEL FOR INTERNAL DOSE


Numerous variables should be considered in determining what the radiation doses
to a population might be as the result of radioactivity released to the environment after
a controlled underground detonation. A workable model can consider only the most
important of these variables if it is to remain useful and if the collection of input data
is to be limited to that which is practicable in a feasibility study. The following equa-
tion represents our attempt to incorporate the essential information into one expression
for estimating internal dose:

t2
Dijk[tlt Z, Y(tl)] Qij Pijk(t) Cij[Y(t),t2-t]dt (rem), (1)
tl


where

Dijk[tl, t2, (t)] = total internal dose equivalent (rem) received during the
time interval t1 to t2 due to radionuclide i in pathway j
at location k from exposure during this time interval
for an individual of age y(tl) at tl,

Qij = quantity (PCi) of radionuclide i released which enters
or is available to pathway j,

Pijk(t) = concentration of radionuclide i in pathway j at loca-
tion k at time t per unit of radionuclide initially
available (pCi/g per pCi released), and

Cij[_(t), t2-t] = the dose commitment (rem/pCi/g per 1-day exposure)
to the reference organ in t2-t days following a 1-day
exposure of an individual then of age y(t) to a unit
concentration of radionuclide i via pathway j.

The term Qij may be thought of as the product of production (inventory) of radionuclide i
and the fraction of this vented or released to some pathway j leading to man. The path-
way term Pijk(t), which is needed to estimate the concentration of radioactivity in each
food or material of intake (called a "compartment" in the jargon of the systems analyst)
is not easily determined when radioactivity moves through complex food-chains, so this
concentration will have to be estimated with systems -analysis techniques.











4-4


THE INREM MODEL FOR ESTIMATING INTERNAL DOSE


When the rate of intake of radioactivity has been determined by the method dis-
cussed in the preceding section, or by some other means, this information is the pri-
mary radioactivity input for estimating the cumulative dose equivalents by the INREM
code. These estimates of dose equivalents are compiled for the various body organs
from inhalation or ingestion of radioactivity programmed as continuous or intermittent
intakes as a function of age. The parameters in the dose equations change as a function
of time as the person ages during the time of intake, or during the period of interest
which may be longer than the period of intake. Biological and physical data applicable
to "standard man" for 105 radionuclides are stored in this code for quick solution of
problems not involving age-dependent factors. The model programmed for all organs
except the GI tract is written

t2 t2


tI tl

s -tb

exp[-5 Xin(7)dY]ds} dt (rem), (2)
t-tb


where

Din(t, t2 tb) = Cumulative dose equivalent (rem) received during the time
interval ti to t2 from the ith radionuclide in the nth organ
resulting from intake during this time interval by an
individual born at tb,

tI = time (days) of initial intake relative to time of reference
detonation,

t2 = time (days) at end of period of interest relative to time
of reference detonation,

tb = time (days) of birth relative to time of reference
detonation,

t = time (days) after reference detonation,

s = time after intake relative to time of reference detonation,

Ii(t) = intake (iCi/day) of ith radionuclide during a unit time
period t,


mn(t) = mass (g) of the nth organ at t,





fin(t) = fractional absorption dimensionlesss) of the ith radionuclide
in the nth organ at t,

Ein(t) = effective absorbed energy (MeV) of the ith radionuclide in
the nth organ at t, and

Xin(t) = effective elimination constant (days-1) of the ith radio-
nuclide in the nth organ at t.

The variables tl, t2, tb, t, and s are measured relative to a reference detonation;
whereas the variables Ii(t), mn(t), fin(t), ein(t), and Xin(t) are functions of the age of
the individual. The code uses Equation (2) for ingestion of contaminated food and water
or inhalation of contaminated air, and calculates the cumulative doses to all organs
except the gastrointestinal tract. When the dose to the tract is calculated, the (MPC)a
or (MPC)w is used in conjunction with age-dependent parameters for intake, mass,
effective absorbed energy, and the unassimilated fraction of intake.



THE EXREM MODEL FOR ESTIMATING EXTERNAL DOSE


The three modes of exposure considered in estimating external dose are: (1) sub-
mersion in the radioactive cloud, (2) submersion in contaminated water, and (3) expo-
sure to a contaminated ground surface. Exposure due to the over-passing cloud may
last only a few hours for each detonation, whereas exposures from the other modes may
persist for longer periods.

The following generalized expression, applicable to any external-exposure path-
way, has been programmed for estimating dose equivalents from external exposure:

t2 N -_ri(t-n)
Dikq(tl, tz, x) = Qinqe Pikn(x)Ciq(x)dt (rem), (3)
t1 n=l

where

Dikq(t1i, x) = total external dose equivalent remss) from beta particles
or photons (identified by the index q) of radionuclide i at
location k accumulated from exposure during the interval
tI to t2 for the mode of exposure x resulting from N'
number of detonations,

tl, t2 = time (hours) entered and time left contaminated area,

x = mode of exposure,

n = detonation number,


N = number of detonations,


4-5










4-6


N' = maximum (n) such that rn < t, N' N,

Tn = time (hours) of the nth detonation,

Qin = quantity (/Ci) of the qth particle or photon of radionuclide i
released from the nth detonation,

Xri = radioactive decay constant (hours-1) of radionuclide i,

Pikn = location correction factor (cm-2 or cm-3) for the ith
radionuclide at the kth location due to the nth detonation,
and

Ciq(x)= dose rate (rem/hr) per pCi/cm2 or cm3 due to beta
particles (q=l) or photons (q=2) of the ith radionuclide
in mode of exposure x.

This model can be used to estimate the accumulated external dose resulting from any
one or all of the three modes of exposure when the proper dose rate equation is sub-
stituted for the term Ciq(x). All of the dose-rate equations used in the EXREM code
are listed and explained in the USAEC document ORNL-4101 by Cowser et al. (1967).
The equation for estimating the dose rate above the ground surface requires that the
height be specified, whereas the two submersion equations assume that the entire body
surface is in contact with a large volume of contaminated air or water. The location
correction factor, Pikn, describes how much of the radionuclide production is present
per cm2 of land surface or per cm3 of air or water, and can be estimated with fallout-
prediction models and systems-analysis techniques.



SEARCH FOR CRITICAL RADIONUCLIDES


Over 200 radionuclides may be produced by an underground nuclear detonation.
The activity of some of these radionuclides will be relatively low and they can be con-
sidered to constitute little or no hazard, especially when the activity is diluted still
further in the environment. Usually when a large number of radionuclides are evaluated
for their contributions to absorbed dose, only a few will deliver most of the dose. It is
necessary to identify these "critical radionuclides" because special emphasis then can
be placed on obtaining more detailed information on their physical and biological behavior
in a given exposure pathway (ICRP, 1965). Sometimes advance knowledge of critical
radionuclides can suggest effective remedial action to reduce radiation exposures. For
example, if 1311 is expected to be a critical radionuclide, certain food products can be
stored or prepared in such a way that the time lag between contamination and ultimate
consumption will be long enough to allow radioactive decay of 1311 (the radioactive half-
life for 1311 is 8.05 days).

Our systematic search for critical radionuclides has been divided into the following
four steps:











4-7


(1) Radionuclide Dose Equivalent List (RDEL) An ordered arrangement of
radionuclides according to (a) external dose from 1 -MCi per cm3 of water, per cm3 of
air, and per cm2 of ground surface; and (b) internal dose commitment from a 1-ICi
single intake by inhalation and ingestion. A Radionuclide Dose Equivalent List does not
consider production, venting, or environmental exposure pathways.

The RDEL of critical radionuclides is developed using several simplifying
assumptions: (a) a unit concentration of each radionuclide in the environment, (b) a unit
intake of each radionuclide, and (c) "standard man" represents the population exposed.
Several distinct populations, each reflecting the characteristics and customs of its
ethnic background, may be exposed in the proposed area for excavation. The RDEL
does not take these factors into consideration.

(2) Radionuclide Dose Equivalent Index (RDEI) An ordered arrangement of
radionuclides derived from a Radionuclide Dose Equivalent List by the incorporation of
production and venting estimates. An index does not include adjustments based on fall-
out predictions or environmental exposure pathways.

The REDI is arrived at by taking each equation used for compiling the REDL's
and multiplying by the production or yield (y/Ci) of each radionuclide and the fraction
vented to the atmosphere. When indicated, the fraction not vented initially may be con-
sidered also, because it represents a potential hazard, especially through movement by
ground water. This index gives conservative guidance because one assumes that all of
the vented material is in 1 cm3 of air or water or on 1 cm2 of ground surface and that a
person is exposed to each of these environmental media.

(3) Preliminary Radionuclide Rank (PRR) An ordered arrangement of radio-
nuclides derived from a Radionuclide Dose Equivalent Index by the incorporation of
information on initial distribution in time and space. A PRR considers fallout predic-
tions, but does not include predictions of radionuclide movement through environmental
exposure pathways.

Fallout predictions, based on production, venting, and meteorological conditions,
expressed on a landscape basis (iCi/cmZ), must be incorporated into the calculations
of PRR. The format of these predictions is most useful when arranged as concentration
contours superimposed on a map of the affected area. A range of arbitrary values is
chosen to represent the fraction of the radioactivity within each dose contour which
might represent intake by man. It is assumed that radioactive decay is the only process
affecting the initial concentration of radionuclides on the landscape. Thus, one can get
conservative or nonconservative guidance from the PRR depending upon the choice of
arbitrary values used to represent the fraction of available radioactivity to which man
is exposed.

(4) Final Radionuclide Rank (FRR) An ordered arrangement of radionuclides
derived from a Preliminary Radionuclide Rank by incorporation of the best available
estimates of radionuclide intakes and/or concentrations of radionuclides in the environ-
ment resulting from redistribution.

A realistic estimate of the potential dose is arrived at by considering how
environmental pathways redistribute the initial distribution of radionuclides on the land-
scape. Situations which involve the total environment are difficult to analyze because











4-8


of their complexity; however, studies of these complex environmental systems may be
expected to reveal a few pathways which have a large influence on the dose received by
man. These are termed "critical pathways", and their identification requires collection
of on-site bioenvironmental data. Improved insight into critical pathways can come
from a sensitivity analysis of each parameter and the effects that changes in the magni-
tude of each parameter have on the compartments of interest. A pathway diagram of
coupled compartments with designated parameters can be drawn when good bioenviron-
mental data have been obtained, or a preliminary diagram, subject to later revision,
may be drawn from whatever sources of experiments and literature are available and
which may prove to be useful. When adequate field data are not available, the latter is
the only alternative.

It is most important to understand that none of these models or methods of esti-
mating radiation dose will provide the final answer as to feasibility of the canal con-
struction project. They were formulated only for a preliminary assessment of
radiological safety-feasibility and are subject to future revisions and refinements.



REFERENCES


Cowser, K. E., S. V. Kaye, P. S. Rohwer, W. S. Snyder, and E. G. Struxness. 1967.
Dose-estimation studies related to proposed construction of an Atlantic-Pacific inter-
oceanic canal with nuclear explosives: Phase I. Oak Ridge National Laboratory.
ORNL-4101.

International Commission on Radiological Protection. 1959. Report of Committee II
on permissible dose for internal radiation. ICRP Publ. 2, Pergamon Press, London.

International Commission on Radiological Protection. 1965. A Report by Committee 4
of the International Commission on Radiological Protection. Pergamon Press, London.

Kaye, S. V. and S. J. Ball. In Press. Systems analysis of a coupled compartment
model for radionuclide transfer in a tropical environment. Proc. Sec. Nat. Symp. on
Radioecology (Ann Arbor, Michigan, May 15-17, 1967).










5-1


PAPER 5. PREDICTING RADIATION DOSE EQUIVALENTS FOR POPULATIONS:
II. RESULTS OBTAINED WITH THE DOSE MODELS.*

P. S. Rohwer and S. V. Kaye**




ABSTRACT



Dose estimates based on anticipated radionuclide production and venting during
excavation of a sea-level canal have been used to identify the radionuclides of greatest
potential importance. Those radionuclides which together contribute approximately 99
percent of the estimated total dose are identified by element. Examples with 3H and
1311 demonstrate the use and the significance of age-dependent dose models. Current
recommendations of national and international authorities concerning the maximum
permissible dose for members of the general population are presented.



INTRODUCTION



Identification of those radionuclides which may contribute the most significant
dose equivalents***' to man is one of the primary objectives of a radiological-safety fea-
sibility study. Dose models which facilitate the fulfillment of that objective are avail-
able, and a stepwise application of those models has been outlined in Part I of this two-
part article on predicting radiation dose equivalents for populations. A quantitative
estimate of radionuclide production and venting during excavation of a sea-level canal
with nuclear explosives was obtained from classified literature. Because of the classi-
fied nature of these input data for some segments of the dose estimation program,
presentation and discussion of the results is limited. Application of the dose models
to the radionuclide production and venting estimates provided dose estimates used to
arrange the radionuclides in descending order of importance for each mode of exposure.
The modes of exposure considered were: submersion in contaminated air, submersion
in contaminated water, exposure to a contaminated surface, and ingestion and inhala-
tion of contaminated air, water, and food. The Radionuclide Dose Equivalent Lists
(RDEL) and the Radionuclide Dose Equivalent Indexes (RDEI) for the external exposure
modes were based on dose rate and total dose, but for the internal exposure modes
(ingestion and inhalation) they were based on total dose delivered to the critical organ.
The critical organ being that organ to which damage by radiation, due to intake of the
radionuclide, results in the greatest injury to the individual or his descendents. Al-
though the RDEL's and RDEI's cannot be presented, lists of critical elements are
included.

The importance of identifying the critical radionuclides has been pointed out in
Part I of this article. Subsequent estimates of movement and/or retention of these
radionuclides in the environment is emphasized in field investigations. Since many of
*Prepared for Battelle Memorial Institute, Columbus Laboratories, under U. S. Atomic Energy Commission, Nevada


Operations Office, Contract AT (26-1)-171.
**Health Physics Division, Oak Ridge National Laboratory (operated by Union Carbide Corporation for the U. S. Atomic
Energy Commission).
**Dose Equivalent (rem) = Absorbed dose (rad) x modifying factors. For the sake of convenience, "dose" is often interchanged
with "dose equivalent" in this paper.











5-2


the potentially critical radionuclides do not exist in the environment in sufficient quan-
tities to be detected, it is necessary to analyze environmental samples for stable
elements. Stable-element data can then be used as an analog for the likely distribu-
tion of radionuclides in the various environmental media at the site of sampling pro-
vided the isotopes are not fractionated and provided the chemical forms of the stable
element and the radioisotopes are the same. Therefore, the radionuclide lists and
indexes were analyzed to identify the important elements. The potential dose for each
element was estimated for each mode of exposure by summing the potential doses of its
radioisotopes. The elements were then arranged in descending order of the summed-
percentage contribution of their radioactive isotopes to the total potential dose in each
mode of exposure. Table 5-1 presents elements representing the radionuclides which
together contributed approximately 99 percent of the total external dose when analyzed
according to the RDEI's which consider radionuclide production and venting but do not
consider initial distribution and subsequent redistribution of the radionuclides. Table
5-2 presents elements representing the radionuclides which together contributed
approximately 99 percent of the total internal dose. With the exception of plutonium,
calcium, and iron, all of the elements appearing in Table 5-2 also appear in Table 5-1.
The lists in Tables 5-1 and 5-2 were obtained by analysis of the element indexes for
the various exposure modes and radionuclide forms (soluble and insoluble) considered
in the dose estimation study. In most cases, the appearance of an element in these
tables is the result of dose contributions from more than one of its radioactive isotopes.
Although the present analyses indicate that these are the elements which have radionu-
clides likely to be of principal importance in the feasibility study, changes and im-
provements in the identification of critical radionuclides or elements can be expected
as more information becomes available. It is important to note that the dose calcula-
tions, which were the basis for compiling the lists of elements in Tables 5-1 and 5-2,
made no allowance for the many factors which may lead to significant differences in
biological availability of the elements. The next step to identify critical radionuclides,
the Preliminary Radionuclide Rank (PRR), requires consideration of the device-
detonation schedule and initial fallout predictions. Environmental redistribution of
the vented and nonvented radionuclides is considered in the Final Radionuclide Rank
(FRR).

Evaluation of exposures to populations requires that dose estimates be made for
all age groups or subgroups identifiable by factors influencing dose within the popu-
lations. The doses to individuals in the population and to the critical population groups
must be evaluated in terms of the permissible dose limits recommended by recognized
authorities. The dose estimates which led to the lists of elements in Tables 5-1 and
5-2 were obtained with "standard man":* parameters in the dose models. "Standard
man" was devised by the International Commission on Radiological Protection (ICRP)
to represent the average Caucasian worker; therefore, "standard man" parameters
probably are not representative of the natives living in Central America. However,
the biological parameters required in the dose-estimation models have been tabulated
for "standard man" for many radionuclides, and it seems prudent to use these in the
absence of data specific for the populations living at the site of the proposed canal.
Age-dependent data to evaluate the biological parameters in the dose models for popu-
lations living in the canal area are not available. Therefore, dose estimates for a few
potentially important radionuclides were made using age-dependent data from Caucasian
populations. The following examples illustrate the use of the INREM code as well as
the influence of age-dependent parameters upon the estimates of dose equivalents.

* "Standard man" is a notional adult designed to represent a typical or average adult who is exposed occupationally.
See ICRP Publication 2 (1959) for details.





5-3












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5-5



Tritium is expected to be produced in large quantities by nuclear devices of the
type which could be used to excavate a canal (Stead, 1963), and preliminary analysis
indicates that it probably would be one of the critical radionuclides. Tritium would be
present primarily in the form of tritiated water (Stead, 1963); and, as such, a large
fraction might move rapidly in the hydrologic cycle of the tropical environment. Tri-
tiated water (HTO) is absorbed readily by man regardless of the mode of exposure -
ingestion, inhalation, or absorption through the skin (Pinson and Langham, 1957;
Osborne, 1966). The dose to the body-water pool, as a result of HTO entering the
body, may be estimated with the INREM dose model [Equation (2), Part I of this
article]. The body-water pool consists of the intracellular fluid, the interstitial fluid,
and the blood plasma. Assessment of the radiation hazard resulting from intake of
HTO on the basis of the dose to the body-water pool is conservative. The body-water
pool constitutes approximately two-thirds of the mass for most body organs (Bard,
1961); therefore, dose estimates based on total-body mass or organ mass would be
lower than those based on the mass of the body-water pool. In fact, if total body was
assumed to be the critical mass absorbing radiation as a result of HTO entering the
body, the dose estimates obtained would be 40 percent lower than those presented here.
The INREM dose model contains several parameters which may be age-dependent:
daily radionuclide intake (li), effective absorbed energy (Ein), fractional absorption of
the radionuclide in the organ (fin), effective elimination constant of the radionuclide in
the organ in o0. 693)
the organ (Xin = ,--- and the mass of the organ (mn). In the case of HTO, fin is

assumed to equal 1. 0 and in is assumed to equal 0. 01 MeV regardless of the age of
the individual. These assumptions are justified because of the ease with which the body
absorbs HTO, and because of the extremely low maximum energy (0. 018 MeV) of the
tritium beta particles (Lederer et al., 1967).

Three parameters had to be evaluated as functions of age before the dose esti-
mates for the population could be calculated. The size of the body-water pool was
estimated from data on total-body weight and the percent of the total-body weight which
is water; such information is available from various sources (Boyd, 1941; Altman,
1961). Size of the body-water pool is presented as a function of age in Figure 5-1. The
biological half-time (Tb) of water in the body-water pool was estimated with the fol-
lowing expression:
In 2 In 2
Tb ~b I'/m (1)


whe re

Xb = biological elimination constant (days ) for turnover of the
body-water pool,
I' = total daily water input (ml/day) to the body-water pool, and
m = size (ml) of the body-water pool.

The equilibrium relationship (Xb = I'/m) may be used because HTO taken into the body
is distributed uniformly throughout the body water, approximating equilibrium in less
than 1 hour (Pinson, 1952). Total daily input to the body-water pool was estimated on
the premise that 1 ml of water is required for each calorie of energy expended (FAO,
1957). Figure 5-2 presents Tb as a function of age. Te is essentially equal to Tb, in


this case, because the radioactive half-life of tritium (Lederer et al. 1967) is long
(12.3 years) relative to the biological half-time of water in the body-water pool





50


45



40



35



30
-J
30
0
0

cc 25



20
0


15



10


o0 I-LII % I -
0 5 10 15 20 40 60 80

AGE (yr)


FIGURE 5-1. SIZE OF BODY WATER POOL AS A FUNCTION OF AGE


5-6







5-7






12










9



"8 /

FEMALE
< 7

-j *
6 /MALE
06
o /5





4



3

2 -.....4---

0 5 10 15 20 40 60 80
AGE (yr)


FIGURE 5-2. BIOLOGICAL HALF-TIME OF WATER IN MAN AS A
FUNCTION OF AGE





evaluate the hypothetical population exposure. As in the case of the tritiated water

*Dose Commitment = the total dose equivalent which an individual will accrue within his lifetime as the result of a
radionuclide intake.


I 'L~


5-8

(3 to 11 days). Daily tritium intake via inhalation can be estimated from data on daily
air intake and the tritium concentration in the air. Figure 5-3 presents estimates of
daily air intakes as a function of age. These estimates are based on age-dependent
data describing daily oxygen consumption (FAO, 1957) and the concentration of oxygen
in exhaled air (Altman et al., 1958), with the assumption that ambient air is 20. 9 per-
cent oxygen. Thus, it was possible to evaluate all of the age-dependent parameters in
the INREM model for estimation of dose due to tritium.

A unit concentration (1 pCi/cm3) of HTO in air was selected for convenience, and
dose estimates for the population were calculated. Age-dependent variation of the dose
commitment* to the body water per day of intake resulting from inhalation of air con-
taining 1 pCi of HTO per cubic centimeter is shown in Figure 5-4. The variation in
dose commitment among the age groups is less than a factor of 1. 5. The values plot-
ted are the infinite dose equivalents remss) resulting, in each case, from a 1-day
intake of air containing 1 pCi of HTO per cubic centimeter. Older members of the
population receive larger dose commitments primarily because of increases in daily
air intake and turnover time of the body-water pool. Since these dose equivalents are
for intake via inhalation, they do not include the concomitant dose equivalents from HTO
absorbed through the skin during the exposure. When HTO vapor is present in air,
approximately equal amounts enter the body by inhalation and by absorption through the
skin (ICRP, 1959). This is assumed to apply for all ages because the ratio of daily air
intake to body surface area is relatively constant as a function of age. Thus, the values
given in Figure 5-4 should be doubled to more accurately estimate the total dose com-
mitments for this hypothetical exposure. Dose equivalents for any exposure to HTO
vapor may be estimated from this figure if the following information is provided: ages
of the individuals exposed (years), lengths of the exposure periods (days), and HTO
concentration in the inhaled air (pCi/cm3). A primary limitation of Figure 5-4 is its
dependence on biological parameters from a Caucasian population; therefore, it is best
applied only when estimating dose equivalents for the population from which the basic
data were drawn. A similar figure should be prepared for each population involved, if
one desires the most accurate dose estimates in a specific situation.

Another radionuclide which would be produced and released to the environment if
a canal were to be excavated with nuclear explosives is 1311. The 131I would be a
short-term hazard because its radioactive half-life is 8. 05 days (Lederer et al.,
1967); however there are environmental pathways (the forage-cow-milk-man-food chain
for instance) which result in rapid movement of radioiodine to man. The thyroid is
considered to be the critical organ for 1311 deposited internally (ICRP, 1959). The
INREM code may be used to estimate the resulting radiation dose to that organ. For
this example a Caucasian population is assumed to ingest fresh milk containing 1 pCi
of 1311 per liter. The age-dependent parameters in the INREM dose model[ Equation
(2), Part I of this article] were taken from Bunch (1966), and are reprinted in Table
5-3. Note that fin does not vary significantly as a function of age in this case. I' is
the daily milk intake measured in liters. Daily radionuclide intake (Ii) is obtained by
multiplying I' by the concentration (/Ci/1) of 13 11 in the milk. Dose estimates were
obtained with each parameter evaluated independently while the other age-dependent
parameters were fixed at their adult (>20 years of age) values. Additional dose esti-
mates were obtained by evaluating the age-dependent parameters in various combina-
tions. Some of the resulting dose estimates are presented in Figure 5-5. The curve
(dashed line) for which all of the parameters were varied with age would be used to








5-9


24



22



20



18


0


o



2



I-
r)
< 12


<0


8



6



4


0 5 40 45 20 40 60
AGE (yr)


FIGURE 5-3. DAILY AIR INTAKE AS A FUNCTION OF AGE


80








5-10


4.0



3.8



3.6



3.4



3.2

C)
E
-3.0
LLJ
U)cn
0
O
2.8



2.6



2.4



2.2



2.0





FIGURE 5-4, A
T
II
C


0 5 10 45 20 40 60

AGE (yr)


80


.GE-DEPENDENT VARIATION OF THE INFINITE REM DOSE TO
'HE BODY WATER PER DAY OF INTAKE RESULTING FROM
INHALATION OF AIR CONTAINING 1 pCi OF HTO PER CUBIC
ENTIMETER





10



9



8



7


3 6 9 42 15 18 21

AGE (yr)


FIGURE 5-5.


SIGNIFICANCE OF AGE-DEPENDENT PARAMETERS IN
ESTIMATING THE INFINITE REM DOSE TO THE
THYROID PER DAY OF INTAKE RESULTING FROM
INGESTION OF MILK CONTAINING 1 pCi OF IODINE-
131 PER LITER


o m VARIED WITH AGE
Sm, I, Te AND E VARIED WITH AGE
A VARIED WITH AGE
A Te VARIED WITH AGE
O I VARIED WITH AGE

















\A \
N-.
N


E
E
0

o


3


n


0


5-11










5-12


example, this curve is dependent on biological parameters from a Caucasian
population.



TABLE 5-3. AGE-DEPENDENT PARAMETERS FOR 1311 EXAMPLE


Age, I', Ein, Te, mn,
yr 1 f MeV days g

0-2 0.5 0.2 0.21 4. 2.0

2-4 0.5 0.2 0.21 4.5 2.5

4-7 0.5 0.2 0.21 5.5 3. 0

7-13 0.75 0.2 0.22 6. 0 5. 0

13-20 1. 0 0.2 0.22 6.5 15. 0
>20 0. 75 0.2 0.23 7. 0 20. 0



The age-dependent variation in the dose to the thyroid is determined primarily by
variation in the mass of the organ. The influence of each of the other age-dependent
parameters (Ii, Ein, and Te) is no greater than a factor of two for any age. These re-
sults could be anticipated upon inspection of the data in Table 5-3. It must be admitted
that the age dependence of Ii, Ein, and Te are not accurately known for a Caucasian
population and even less is known concerning them for the populations of primary con-
cern in this study. Age-dependent variations in final dose estimates would not be as
easily predicted by data inspection for radionuclides with long effective half-times
and/or greater variability in their age-dependent parameters. Considering 137Cs, for
example, reports in the literature indicate that both organ mass (mn) and effective
half-time (Te) may vary by approximately an order of magnitude during the lifetime of
man. In the case of 90Sr, the dose estimates would reflect the influence of age-
dependent variations in mn, Te, and fin. Figure 5-5 shows that the dose to the thyroid
of an infant, as a result of 1311 ingestion, could be underestimated by a factor of 3.5
if age-dependent changes in the biological parameters were ignored. On the other hand,
considering the change in mass of the thyroid while ignoring the less apparent varia-
tions of other age-dependent parameters could result in a nearly threefold overestimate
of the dose to the thyroid of an infant. This example illustrates both the need to evalu-
ate the age-dependent parameters in the dose estimation models and the importance of
considering them collectively as programmed in the INREM code.

After the radiation doses received by the population have been estimated for the
various segments of the populations, they must be compared with appropriate
radiation-safety guidelines to determine whether or not they fall within the limits con-
sidered acceptable. Table 5-4 presents the annual dose levels recommended for mem-
bers of the general population by the International Commission on Radiological
Protection (ICRP, 1966), the International Atomic Energy Agency (IAEA, 1962), the
National Committee on Radiation Protection and Measurements (NCRP, 1958, 1959),
and the Federal Radiation Council (FRC, 1960, 1961). These values have been recom-
mended for "normal peace-time operations". They are considered to entail a low level
of risk when balanced against the benefits normally occurring to individuals and to

















5-13


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5-14


society from the conduct of peaceful nuclear operations. There appear to be no impor-
tant differences among the recommendations of these recognized authorities concerning
permissible exposure levels for members of the general population. However, it is
important to point out that all of these authorities assumed the "linear hypothesis"
relating dose and effect in arriving at these annual dose levels. This assumption im-
plies that there is some risk, however small, involved in any exposure to ionizing
radiation. Thus, these authorities declare the policy that no unnecessary exposure is
justified, and any operator is obligated to minimize population exposures below permis-
sible levels whenever this can be done without significantly impeding the operation.

Age-dependent models are available for use in estimating dose equivalents to
populations for internal- and external-radiation exposures. The models can be applied
to hypothetical situations, such as the canal feasibility study, to identify the radio-
nuclides of greatest potential importance. Unfortunately, the application of the dose-
estimation models is limited by a paucity of information. The primary need for this
study, and additional investigations into the radiological-safety feasibility of excavating
a canal with nuclear explosives, is a collection of the necessary data on movement of
radionuclides in the environment and on the biological parameters characterizing the
exposures of indigenous populations such that realistic dose estimates can be made.
The radiological-safety feasibility of the project could then be judged by balancing the
benefits and risks.



REFERENCES

Altman, P. L., J. F. Gibson, Jr., and C. C. Wang. 1958. Handbook of Respiration.
W. B. Saunders Co., Philadelphia.

Altman, P. L. 1961. Blood and Other Body Fluids. Federation of American Societies
for Experimental Biology, Washington, D. C.

Bard, P. 1961. Medical Physiology. C. V. Mosby Co., St. Louis.

Boyd, E. 1941. Outline of Physical Growth and Development. Burgess Co., Minnesota.

Bunch, D. F. 1966. Controlled Environmental Radioiodine Tests Progress Report
Number Two. U.S.A.E.C. Doc. IDO-12053.

Federal Radiation Council. 1960. Background Material for the Development of Radia-
tion Protection Standards. Report No. 1. U. S. Government Printing Office,
Washington, D. C.

Federal Radiation Council. 1961. Background Material for the Development of
Radiation Protection Standards. Report No. 2. U. S. Government Printing Office,
Washington, D. C.

Food and Agriculture Organization. 1957. Calorie Requirements. FAO Nutr. Studies
No. 15.

International Atomic Energy Agency. 1962. Basic Safety Standards for Radiation
Protection. Safety Series. Publication 9. Vienna.











5-15 and 5-16


International Commission on Radiological Protection. 1959. Recommendations of the
International Commission on Radiological Protection. Report of Committee 2 on
Permissible Dose for Internal Radiation. ICRP Publication 2. Pergamon Press,
London.

International Commission on Radiological Protection. 1966. Recommendations of the
International Commission on Radiological Protection. ICRP Publication 9. Pergamon
Press, London.

Lederer, C. M., J. M. Hollander, and I. Perlman. 1967. Table of Isotopes. John
Wiley and Sons, Inc., New York.

National Committee on Radiation Protection. 1958. Maximum Permissible Radiation
Exposure to Man. Supplement to N. B.S. Handbook 59. U. S. Government Printing
Office, Washington, D. C.

National Committee on Radiation Protection. 1959. Maximum Permissible Body
Burdens and Maximum Permissible Concentrations of Radionuclides in Air and Water
for Occupational Exposure. N.B.S. Handbook 69 and Addenda. U. S. Government
Printing Office, Washington, D. C.

Osborne, R. V. 1966. Absorption of tritiated water vapour by people. Health Phys.
12: 1527-1537.

Pinson, E. A. 1952. Water exchange and barriers as studied by use of hydrogen
isotopes. Physiol. Rev. 32: 123-134.

Pinson, E. A. and W. H. Langham. 1957. Physiology and toxicology of tritium in
man. J. Appl. Physiol. 10: 108-126.

Stead, F. W. 1963. Tritium distribution in ground water and around large underground
fusion explosions. Science 142: 1163-1165.











6-1


PAPER 6. DEMOGRAPHIC AND DIETARY DATA FOR
HUMAN GROUPS INHABITING THE EASTERN
REGION OF THE REPUBLIC OF PANAMA*

Reina Torres de Arauz*.



ABSTRACT



The human population of eastern Panama is composed primarily of Cuna Indians,
Choco Indians, Negroes, and recent colonists from western Panama. The subsistence
economy of all these groups is based on shifting agriculture, fishing, hunting, and
gathering. The composition of the diets of each group is strongly influenced by the
immediate environment whether it be estuarine, coastal, insular, or fluvial. Demo-
graphic and dietary data are discussed in relation to the environment of each cultural
group.



DEMOGRAPHIC DATA



The area studied (Figure 6-1) comprises the eastern portion of the Province of
Panama, the Province of Darien and the eastern portion of San Bias between the villages
of Ailigandi and Puerto Obaldia. The territory covers approximately 26, 938 square
kilometers, corresponding to a third of the total area of the Republic of Panama
(77, 882 km2).

Jungle vegetation occupies most of the area and the human population density
(1.8 inhabitants per km2 in Darien) is low. The National Census of 1960 indicated a
total of only 47, 541 people in this region, but considering the highest and the lowest
population growth rates observed in the area (Table 6-1), the current (1968) population
is probably between 53, 500 and 61, 000.

The human population of the area (Figure 6-1) was divided, for study, into five
human groups as follows:

Group A: San Bias Cuna Indians who inhabit the islands stretching from
Ailigandi to Anachucuna.

Group B: Cuna Indians who live on the upper Chucunaque River and the
upper Bayano River.

Group C: Choco Indians who are scattered throughout the Province of
Darien and also are found in the district of Chiman in the
Province of Panama.


*Prepared for Battelle Memorial Institute, Columbus Laboratories, under U. S. Atomic Energy Commission, Nevada Operations
Office, Contract AT(26-1)-171.


**Director, Human Ecology Program, University of Panama.


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6-2







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6-3


Group D: Negroes and mestizos who are found chiefly around the Gulf
of San Miguel.

Group E: Colonists from western Panama (the provinces of Chiriqui,
Herrera, Los Santos, and Veraguas) who have settled at
several points in the Province of Darien and in the district
of Chiman.

To obtain up-to-date demographic data for this area, preceded questionnaires
were distributed to 9, 000 individuals in 1, 400 houses. These data were used to estimate
the rates of natality and mortality, as well as other demographic variables, for each
human group. The results of this study are summarized in Table 6-1.

TABLE 6-1. RESULTS OF DEMOGRAPHIC SURVEY


Cultural Groups(a)
Demographic Parameters A B C D E
Reproduction Rate, children per female 2.7 2.7 3.4 3.4 3. 1
Child Mortality Rate, deaths per year 156 206 187 96 92
per 1000 live births

Life Expectancy at Birth, years 46 38 42 56 58

Birth Rate, b = births per year per 1000 pop. 40 40 47 45 42

Death Rate, d = deaths per year per 1000 pop. 19 25 21 13 13

Natural Growth Rate, (b d) 21 15 26 32 29

(a) Cultural Groups A-E are described in the text.


The infant mortality rate and the death rate are highest among the Cuna Indians of
the upper Bayano and Chucunaque (Group B) where the possibility of receiving medical
assistance is virtually nil. The lowest death rates and infant-mortality rates occur
among the Negroes and colonists (Group D and E) who live closer to communities such
as La Palma and El Real where modern medical facilities are available.

As shown by the gross rates of reproduction, all groups have high levels of
fecundity. The rate shown is the number of children that a newly born female may have
during her reproductive years if existing conditions remain the same. Women of the
five groups have the highest rate of fecundity between the ages of 20 and 25.


Ecological Patterns and Human Population


The populations of the study area can also be subdivided (Table 6-2) according to
the kinds of habitats (estuarine, coastal, insular, fluvial) from which they derive part
or all of their food, water, and the other materials required for subsistence. For
example, there are (based on the National Census of 1960) about 17, 000 people, mostly
non-Indians, who live on the shores of the Gulf of San Miguel and thus have access to
various estuarine ecosystems. About 15, 000 people, including the majority of the












6-4



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6-5

Choco Indians, some Negroes and some Cuna Indians, live inland along rivers and thus
obtain part of their food from riverine (fluvial) ecosystems. Some of the Negroes
(Puerto Obaldia on the Caribbean and Garachine on the Pacific, for example) live in
coastal habitats while others occupy insular habitats (Las Perlas Islands, for example).



SUBSISTENCE CULTURE


In all the different cultural groups and in the different habitats, the subsistence
economy of the area is similar. It depends primarily on shifting agriculture and
secondarily on fishing in the rivers and marine habitats available. Livestock and
poultry raising is third, hunting is fourth, and gathering wild fruits is fifth in rank as
methods of obtaining food. However, the methods employed in these different sub-
sistence activities and the species utilized by the different cultural groups depends to
a significant extent on the kinds of bioenvironments available at different locations.


Agriculture

The agricultural systems employed by the different cultural groups are: shifting
cultivation, riverine agriculture, plantation agriculture, and dooryard agriculture.
The characteristic type of agriculture, shifting cultivation of the slash-burn type, does
not produce high yields because the native population lacks the technology required to
utilize the land to its maximum advantage; the condition of the soil and the lack of plows
and fertilizers contribute greatly to the migratory character and the low yields of
shifting agriculture. In spite of this, agricultural products account for 70 to 90 percent
(Table 6-2) of the total diet.

The Cuna Indians of the San Bias Islands have coconut plantations along the coast
and on some islands, but the principal areas of cultivation are along the mainland rivers
and on the sides of the low mountains bordering the Caribbean coast. Dooryard agri-
culture is limited because of the small size and poor soil of the islands.

These four agricultural systems are practiced by all the groups. While shifting
cultivation is the most important, plantation agriculture is very important among Choco
Indians and Negro farmers who are engaged in the intensive cultivation of plantain and
banana for commercial purposes. The colonists combine shifting agriculture with
cattle-raising which takes them inland and away from the river banks. The cleared
lands of these people are becoming anthropogenic savannahs due to the establishment
of pastures to further livestock-raising.


Fishing

Fishing in the rivers, estuaries, and oceans of the area is the most frequent and
expedient way of obtaining animal protein. Maritime fishing by natives of the study area
is rather limited, but shrimp boats from the Gulf of Panama often bring part of their
rich cargo to the towns bordering the Gulf of San Miguel to sell or simply give it away










6-6

to the people. With the exception of the colonists, who are primarily cattle-raisers,
sea and river fish are the most important sources of animal protein. As can be seen
in Table 6-2, fish account for 6 to 17 percent (by weight) of the diets of the other
subpopulations.


Hunting

Though less important than fishing, hunting also provides a source of protein in
the form of birds and mammals. Group B shows a higher percentage consumption of
game than the other groups; this reflects the greater availability of birds and mammals
in the upper Bayano and upper Chucunaque areas. Usually, game is consumed fresh,
but when the hunting is good, excess meat may be preserved by salting, smoking, or
sun drying.


Animal Husbandry

Domesticated animals such as chickens, ducks, and pigs are common throughout
the area. Their basic nourishment is corn and rice, but pigs are also fed plantain,
squash, and root crops. It is customary in the region to allow domesticated animals to
run wild allowing them to complement their nourishment with worms, insects, human
and animal residues, and wild plants.

Livestock-raising is becoming commercially and locally more important. This
is due primarily to the tendency of colonists to combine agriculture with cattle-raising.
The result is a general movement of the population inland away from the rivers as
more and more forest areas are cleared and converted to artificial pasture.


Gathering

The gathering of wild fruits is a seasonal practice, which contributes very little to
the total diet. "Raicilla" (Ipecac) is the only item gathered for commercial purposes.


Potable Water

Water for drinking, cooking, and preparing beverages is usually obtained from
rivers or creeks. In a few places, such as La Palma, Puerto Obaldia, and Garachine,
there are rudimentary aqueducts. Artesian wells are limited in number and a few
people in some parts of San Blas and in La Palma collect rain water, especially during
the rainy season.


Transportation

Transportation utilized by the different human groups are related to their habitat
and cultural associations. The many rivers of the area are the major routes of trans-
portation, and the dugout canoe is the most common vehicle, but other types of boats










6-7


are also fairly common. Recent colonists have introduced horses and oxcarts, but
roads are virtually nonexistent. Travel between the upper Bayano and the San Blas
Islands is still done on foot, but transportation by air is available between Panama City
and many points in the study area.



MATERIAL CULTURE OF THE HUMAN GROUPS


Cuna Indians (Groups A and B)

These groups represent one culture and one language but they are found in two
different habitats. Group A is found in the coastal-insular region known as the Comarca
de San Blas. In the Census of 1960 the San Bias population was approximately 19, 340.
Group B, the Cuna Indians of the Chucunaque and the Bayano rivers, consists of about
1, 500 people. Their habitat is typical of the tropical jungle, and most of them live in
riverside settlements. Their presence in two different habitats justifies the recognition
of two different groups. Group B, because of its isolation is culturally conservative and
shows little evidence of either acculturation or cultural progress. Group A, on the other
hand, is culturally progressive. They have eagerly accepted the efforts of governmental
and charitable organizations to establish educational and medical facilities on the islands.
They carry on a lively trade (exporting coconuts, avocados, and other seasonal fruits,
and importing various trade goods) with other parts of Panama and with Colombian
trading vessels; and they have encouraged tourism by building small hotels and opening
landing fields for light aircraft on several of the islands.

The San Bias Cuna population is relatively static, and the natural growth rate is
only 21 per 1, 000. The 1960 Panamanian Census report suggested that the population
of San Bias will diminish by 1970 to 18, 860. The decline of the Chucunaque and Bayano
population (Group B) may be even greater because the natural growth rate is only 15 per
1, 000 inhabitants. The endemic and epidemic illnesses that have swept the region are
undoubtedly the principal causes for this situation.

Almost everything required for the subsistence of these two groups is extracted
from their immediate environments. The principal agricultural products are plantain
(Musa paradisiaca) and bananas (Musa sapientum). Both plantain and banana are com-
mon in the upper Bayano-Chucunaque area, but plantain is relatively rare in the San
Blas area. The weekly adult consumption of plantain-banana amounts to 12. 5 kg in the
Bayano-Chucunaque area, and 9.0 kg in the San Blas area. The second and third most
important agricultural products are corn and rice, but more than two dozen crop species
(including root crops such as manioc, yam, and sweet potatoes, and fruits such as
avocado, cacao, and papaya) are commonly cultivated.

As shown in Table 6-2, hunting is much more important in the Bayano-Chucunaque
area than in the San Bias area. The collared peccary, agouti, and tapir are among the
most common mammals taken while the most frequently taken birds are curassow, guan,
and parrot. The relative unimportance of game in the San Blas diet reflects the increase -
ing dependency of this group on imported foods and the difficulty of hunting excursions
in the mountains. Due to their inland locations, maritime products are not available to










6-8


Group B; but sea fish and other marine food species account for 11.3 percent (by weight)
of the San Bias diet. By the same token, the San Bias do little or no fishing in rivers
while the Bayano-Chucunaque group makes extensive use of fluvial food sources.

The isolation of these two groups is not great. They communicate by means of
paths cut through the San Blas mountain range. Especially during the dry season, the
Cuna from the continental region visit the San Bias Islands to sell smoked meat, agri-
cultural products such as cacao, and cosmetics made from the seeds of achiote (Bixa
orellana). Such visits are profitable and the visitors buy manufactured articles such as
clothing, cooking oil, flour, salt, and other "luxury" items. The San Blas Cuna follow
the same paths and visit relatives that live in the Bayano-Chucunaque area; at the same
time, they may buy tobacco or go out on a hunting excursion. These hunting excursions
are granted by permission of the political chiefs of the mainland region.

Contact between the mainland Cuna and the other human groups of the study area
is rare, and this is due more to volitive reasons than to geographical isolation. The
rivers of the region should facilitate such contact, but the Cuna community voluntarily
maintains its isolation and expressly denies admission to the vehicles of acculturation.


The Choco Indians (Group C)

In 1960 there were 5,475 Choco Indians in the region of study. Mostly, they are
dispersed along the upper reaches and tributaries of the most important rivers in the
region: Jaque, Sambu, Tucuti, Chucunaque, and Tuira. The subsistence economy
based on shifting agriculture is supplemented by the intensive cultivation of plantain and
rice for commercial purposes. As with the other groups, plantain and banana, espe-
cially plantain, are the main elements of their diet. In order of importance, these are
followed by rice, corn, and root crops. The agricultural products account for 83. 7
percent of the total diet.

River fish, mollusks, and crustaceans are the main sources of animal protein.
There is remarkably little selectivity displayed in regard to fishing, and virtually every-
thing caught goes into the pot. As shown in Table 6-2, river fish account for some 7. 6
percent of the Choco diet. Small groups of Choco living around the Gulf of San Miguel
(not shown on the map) consume similar quantities of sea fish.

Certain mammals such as agouti (Dasyprocta punctata), white-lipped peccary
(Tayasu peccary), collared peccary (Pecari tajacu), and brocket deer (Mazama
americana) are preferred, but other mammals such as monkeys and various kinds of
birds are also taken, as are iguanas and a few other reptiles. Chickens and pigs are
raised to a limited extent; and as shown by Table 6-2, the consumption of game and
domestic animals is about equal (7.5 percent) to the consumption of fish and other
aquatic organisms.

The relationship between the Choco Indians and their habitat is close, not only in
regard to diet but also in regard to the collection of wild plants used in house construc-
tion, as medicines, or as cosmetics. Virtually everything they require for subsistence
is available in their immediate environment. The only imported items commonly seen
in Choco homes are articles of clothing, household utensils such as aluminum pots,
and transistor radios.





The Negro Population (Group D)

The Negro population of the study area, approximately 19, 925, has the highest
population growth rate (32 per 1, 000) of all the groups studied. The death rate is one
of the lowest (13 per 1, 000), and the birth rate is one of the highest (45 per 1, 000).
Demographically, this is the most important group of the region. Its geographical
distribution is largely estuarine or coastal because many of the larger and economically
more important Negro villages, such as La Palma, Rio Congo, Garachine, and
Chepigana, are located on the Gulf of San Miguel. Another segment of the Negro popu-
lation shows a fluvial riverinee) distribution in villages such as El Real, Pinogana, and
Yaviza. Population data for the non-Indian inhabitants of the area show that 56 percent
live near estuarine or coastal zones, while 32 percent live along the principal rivers
of the region. The insular subgroup of the Negro population, about 12 percent, is
confined to Las Perlas Islands (Figure 6-1).

The economy of this group is also based on the "slash and burn" type of shifting
agriculture. The principal agricultural products, in order of their importance in the
diet are rice, plantain, corn, and edible roots such as yams, manioc, and sweet potato.
The Negroes of fluvial habitats are somewhat more dependent (Table 6-2) than those of
other areas on agricultural products.

The relationship between habitat and diet is perhaps best illustrated (Table 6-2)
by the proportions of river fish (plus other freshwater organisms) and sea fish (plus
other marine organisms) in the diets of different groups. The consumption of river
fish (6. 9 percent) by Negroes (Group D2) living near rivers is comparable to that of
riverine Indian population (Groups B and C). The same relationship holds in regard to
the consumption of seafoods by populations of estuarine and coastal habitats (Groups A,
Dl, and D3), but the consumption of seafoods by the Negroes of Las Perlas Islands
(Group D4) is significantly higher (17.2 percent) than that of any other group.

The hunting of game animals and wild birds contributes less to the diets of Negro
populations than it does to the diets of inland Cuna and Choco Indians, but the consump-
tion of domestic animals such as chickens, hogs, and cattle is generally more important.
In La Palma, for example (not shown in Table 6-2), 14.2 percent of the diet is made up
of poultry, pork, and beef: 8.4 percent is beef. In this instance, the high rate of
domestic animal consumption is related to the relatively high level to which a money
economy has developed. La Palma is the capital of the Darien Province and a rela-
tively large percentage of the population is composed of salaried government workers,
merchants, and tradesmen who have money enough to purchase the poultry, pork, and
beef raised in other parts of the region but brought to La Palma for butchering and sale.

The development of a money economy is also responsible for the fact that the con-
sumption of foods imported from outside the study area items such as canned meats,
canned fish, carbonated beverages, beer, rum, bread, crackers, cookies, etc. is
also relatively high, ranging from 2. 7 percent among the Negroes of fluvial habitats to
15.3 percent of the total diet of the urban population of La Palma. In fact, the con-
sumption of imported products (Table 6-2) seems to be a fair indicator of the extent to
which the different population groups are or are not dependent upon their immediate
environment to provide the items required for subsistence.

Historical and political factors are also involved in the gradually decreasing
dependency of these groups upon their immediate environment. The building of primary


6-9


I










6-10


and secondary schools by the federal government, the establishment of two hospitals,
and the existence of national agricultural agencies, etc., have all contributed to rapid
cultural progress and the transition from a subsistence economy to a money-based
economy and a mode of life with semiurban characteristics.


Colonists (Group E)

Recent settlers from the western part of Panama (about 1, 300 people) constitute a
minority of the population, but they are bringing about some serious ecological changes
in the region. They have brought with them the agricultural practices which are charac-
teristic of the regions of their origin (the Azuero Peninsula, central provinces of
Panama, and Chiriqui). They are rapidly clearing large areas of jungle for agricultural
purposes and especially for the planting of pastures and the establishment of cattle.

In their culture, cattle-raising is not just an economic undertaking, it also imparts
a high degree of social prestige. Under their influence, cattle-raising has been popu-
larized throughout the region, and "small cattlemen" have begun to appear among the
Negro and Choco Indian populations as well. The colonists are the only group for which
the consumption of milk and dairy products is of any importance. It is also the group
(Table 6-2) in which the average consumption of cattle and poultry products is highest
(7. 7 percent).

This group is also strongly influenced by the environment, not so much because of
present cultural patterns, but because they live in incipient colonies and are poor; they
must take maximum advantages of natural resources and keep to a minimum the con-
sumption of purchased products. This explains the high percentage of agricultural
products (88. 9 percent) and the low percentage (1.0 percent) of imported products in
the average diet. Likewise, fishing and hunting contribute little to the colonist's diet
because the work of raising crops and cattle leaves little time for such activities.


Exports

Another matter, important to the radiological-safety feasibility studies, is the
export of vegetable and animal products from this region to other provinces of the
Republic of Panama and to different parts of the world. The principal agricultural
exports are plantain, rice, and yam. The region under study supplies most of the
plantains consumed in the Province of Panama and in some of the central provinces
as well, and plantain is an element of daily consumption throughout the Republic.
Exportation of rice and edible roots is also important and helps to fill requirements
of other parts of Panama. The vast timber lands of the region are continuously
exploited for exportation purposes. It is estimated that 7, 000, 000 board feet of lumber
for fine furniture and construction purposes are shipped every year to the Province of
Panama from the Darien Province. Shrimp fishing, while not confined to the study
area, is common throughout the Gulf of Panama and the Gulf of San Miguel. Most of
the 12 to 15 million pounds of shrimp taken annually is exported to the United States.






1


6-11 and 6-12


REFERENCES



Contraloria General de la Republica, Lugares Poblados. Sexto Censo de Poblacion y
Vivienda, Direccion de Estadistica y Censo, Panama, 1962.

Contraloria General de la Republica. Poblacion Indigena. Sexto Censo de Poblacion y
Vivienda, Direccion de Estadistica y Censo, Panama, 1964.








PAPER 7. HUMAN ECOLOGY OF NORTHWESTERN COLOMBIA (THE CHOCO)*


Felix Webster McBryde**
Alfredo Costales Samaniego***


ABSTRACT


The three municipios most likely to be affected by canal construction along
Route 25 in Colombia were studied intensively. The total population of the area studied
is 8, 581: 52 percent Negro, 25 percent white and mestizo, 8 percent Indian (Cuna
and Choco), and 4 percent indeterminate racial mixtures. While the subsistence culture
of the region is predominantly agricultural, only about 5 percent of the arable land is
presently under cultivation. Typical diets of the area are composed primarily of
plantain and banana, rice, corn, root crops, game, and fish. Cattle raising is of
increasing importance, and dairy products are locally important dietary constituents.




HUMAN RESOURCES


Demographic Aspects

Three municipios of the Departamento of El Choc6, Colombia, will be affected by
canal construction if it is decided to use Interoceanic Route 25. These are Riosucio,
Acandi, and Jurad6, the only ones included in the demographic study. They comprise
24 corregimientos, having approximately 11, 972 square kilometers, and a total popu-
lation of 16, 763 (1964 Colombian national census), some concentrated in small
villages, but most dispersed through the jungles and marshlands.

Santa Maria corregimiento, with 36 percent of the population, and Unguia, with
29 percent have a combined total of 65 percent in the Atlantic area, whereas only
35 percent is in the Upper Atrato and the Pacific coastal areas, which are much larger
geographically.

Selected for sampling were 1, 557 families (8, 581 individuals) in scattered
dwellings or in the 92 small populated centers of the seven corregimientos, three in the
Municipio of Riosucio, two in Acandi, and two in Jurado. Some of the villages studied,
but not the municipios or corregimientos, are shown in Figure 7-1.

The Departamento population (1964) is 182,419, with 42, 581 classified as "urban",
living in small village nuclei, and 139, 838 rural, widely dispersed through the
remaining region. Of the Departamento total, about 5 percent of the population was



*Prepared for Battelle Memorial Institute, Columbus Laboratories, under U. S. Atomic Energy Commission, Nevada Operations
Office, Contract AT(26-1)-171.
"*Battelle Memorial Institute, Columbus Laboratories.
**"Ecuadorian Institute of Anthropology and Geography.


(The authors wish to acknowledge translation assistance by Mrs. Elinor K. Willis)


7-1
























NORTHWESTERN


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FIGURE 7-1. AREA OF ROUTE 25 STUDY


7-2


COLOMBIA


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studied intensively by the human ecology team. This represents 51 percent of the total
population of the three municipios selected.


Population of the Study Area by Ethnic Groups

Widespread acculturation blurs the ethnic picture, as can be explained by a
historical analysis of the population.

The "libres", as Negroes are usually called, were imported for the most part in
colonial times as mining slaves; they make up 52 percent of the population studied. Of
African origin and modified by Americanization, this group is the most representative,
not only of the area under study, but of the entire Departamento.

Whites and mestizos form a group which is slowly growing stronger through
migration, and represents some 35 percent of the total.

The "cholos", or Indians, represent only 8 percent, perhaps indicating a trend
toward ethnic extinction through voluntary seclusion and dispersal. Only the Cuna and
the Choco groups have survived, and these Indians constitute a minority which is slowly
becoming diluted through intermixture with Negroes and mestizos.

The group classified as "mixed" comprises those communities in which it is
impossible to separate various ethnic elements and accounts for 4 percent of the total.


Movements of Population

The Choco is an area of relatively recent colonization, with low population density
and ample natural resources, two factors conducive to spontaneous settlement,
especially notable during the last 5 years.

In broad terms, 82 percent, or 7,016 inhabitants, are recent migrants, while
only 18 percent are long-established residents.

Population movements were studied in three regions: The Atlantic coast and lake
region, including the foothills of the Serrania del Darien (Sautata, Unguia, and Santa
Maria la Nueva, or Cuti); the Upper Truando and Salaqui, in the foothills of the Cerros
de Quia; and the Pacific Coastal area (Curiche and Coredo).


Atlantic Lake Region. Though the region has elevations from sea level to more
than 2,000 meters, it consists largely of a complex of low-lying lakes and swamps which,
with the wide Atrato itself, allow easy navigation and communication. The seasons are
marked as to rainfall which, although high, permits cattle raising. Migrations in this
area show a heavy interdepartmental flow which is a frontier movement involving whites
and mestizos from the Departamentos of Bolivar, Cordova, Antioquia, El Valle,
El Atlantico, and Santander. The corregimientos of Sautata, Unguia, and Santa Maria,
Departamento of El Choco, are those in which migration is most important. This
spontaneous movement is encouraged by the Departamento of Antioquia, in expectation
of possible territorial annexation. Here the white has a strong prejudice against the
"libre", who reacts with an exaggerated sense of ethnic pride.


7-3










7-4


The heavy migration in this region has accounted for 78 percent of the migrant
population in the study area, where they show a tendency to form nucleated centers.


Upper Truando Region. This area of widely meandering rivers has attracted a
large number of former slave Negroes and, some Indians, from other parts of the
Departamento of El Choco, who engage in lumbering and subsistence agriculture. This
represents only 16 percent of the total migration in the study area, which is low consid-
ering the rich potential of the environment.


The Pacific Region. Because of the somewhat unhealthful quality and isolated
character of this area, migration is only 3 percent (217 persons).

Population movements, especially in the lower Atrato region from the Cararica
River to Sautata, exhibit a drainage of peoples from older, more congested zones of the
contiguous Departamentos.


Population by Occupation


Primary Occupations. Among primary occupations that is, those upon which
the populace depends for survival the breakdown of the 68 percent total is as follows:
tillage agriculture 51. 5 percent, agricultural day labor 8. 5 percent, stock-raising
5 percent, and fishing 3 percent. The preponderance of agriculture is explained by the
subsistence offered and minimum capital investment required. In the past 5 years,
stock raising has developed significantly as a primary occupation.


Complementary Occupations. Since agriculture is seasonal, people find time for
a variety of complementary activities, principally in merchandising (4 percent), and
muleteering or packing on animals' backs (3 percent).


Undefined Occupations. Constituting 11 percent of the complementary occupations,
these are termed "disguised" and correspond to seasonal, temporary, unstable move-
ments, in which job hunters offer their services in such varied activities as witch
doctor, herb gatherer, pot vendor, ipecac collector, and some are vagrants, at times
creating serious social problems.

Occupations are less diversified when people are mobile than they are in a
stabilized population nucleus. Primary occupations are common to all groups, for, in
embryonic communities, the same person may perform one or several functions. As
populated centers become more stable, the separate identity of a variety of specialized
activities develops apace, with individuals tending to assume occupational specialties
full-time.





LAND RESOURCES AND AGRICULTURE


Land Re s sources

The vast land resources of El Choco provide its chief economic basis. Land-use
percentages on the 407, 950 hectares in the seven corregimientos studied are as follows:

Not suitable for cultivation, 25. 05 percent; suitable for cultivation but not
presently in use, 69. 17 percent; timberland, 0. 75 percent; and cultivated land,
5. 03 percent. This land is newly or fairly recently occupied and represents a natural
resource of immediate potential.


Land Under Cultivation

The low percentage under cultivation, 5 percent, reflects low population density.
Cultivated land is used as follows:

Pasture grass (artificial pasture), 28 percent, followed by the historically older
crop, rice, 26 percent. The increasing importance of stock raising, especially in
Sautata, Unguia, and Santa Maria (Cuti) accounts for this trend. Corn, the basic staple
of consumption, has risen progressively in the past 5 years, and now amounts to
24 percent. Other crops, such as fruit, yuca, iame, sesame, and sugar cane, are less
important, but have their place in the local diet and market, accounting for 7 percent
or 1,428.22 hectares.

While agriculture is expanding principally in stock-raising, rice, and corn, other
crops such as cacao and coffee, formerly in great demand in the local market, have
disappeared almost completely because of insect pests and disease.


Land Tenure and Agriculture Labor Conditions

Although accurate quantification here is impossible, some problems are listed
below:

Land tenure, in new and recent zones, involves a variety of serious problems.
Spontaneous settlements result in de facto occupation of land without legal title, which
in turn gives rise to dispossession and litigation. The farming population may be
divided into two main demographic groups: the "libres", who are little attached to the
land, and the "cholos", who have a close attachment with the land. Neither group is
protected by legal title. The presence of these squatters creates one of the most
serious problems in the Choco.

The Colombian Agrarian Reform Institute (INCORA) is gradually helping farmers
to obtain titles.


Agricultural Labor Conditions

The agricultural laborer lives at almost subhuman subsistence levels. The


so-called "slave laborer", or razo, earns 20 pesos (at 16. 25 pesos to the dollar) a day


7-5










7-6


without food; the common laborer, 15 pesos (or about 90 cents U.S. ) with food. Work is
also done by the job or by the hectare, sometimes by exchange labor and contract.
Salaries, which vary according to supply and demand, and the age and sex of the
laborer, are often paid in kind (rice, corn, or plantain). While the landless laborer is
bound by these conditions, the small or medium-sized proprietor is helplessly subject
to the voracity of the local merchants, who provide food, money, seed, and tools in
exchange for produce at ridiculously low prices. This is one of the most serious prob-
lems in rice-producing areas.


Cultivation Methods and Agricultural Tools

Farming techniques depend directly on hand tools, the majority of which are
long-outmoded, like the machete, hoe, handspike, iron knife, hatchet, wooden shovel,
wooden grapnel, etc. Only for stock-raising is new agricultural machinery being intro-
duce d.

Cultivation methods are also antiquated because the small farmer is too poor for
mechanization. Slash-and-burn clearing is the rule, to take advantage of the shallow
upper layer of fertile soil; artificial fertilizers are almost unknown. An elementary
system of crop rotation is associated with this nomadic agriculture. Terracing is used
on slopes, especially for grazing.



MEANS OF SUBSISTENCE


The migratory population found in the Choco is basically dependent on subsistence
resources which may be divided, according to their importance, into primary and
secondary, or complementary.

The primary resources include the products of agriculture, hunting and fishing,
which support both natives of the area and migrants.


Agriculture, Including Gathering. Although antiquated and lacking in advanced
techniques, agriculture is one of the most important means of subsistence in the region,
producing 43 principal cultivated crops, with 186 varieties; also, 31 edible forest
products are gathered for food.


Fishing. As a means of subsistence, fishing is as important as agriculture. The
great majority of fishing methods are indigenous, having been adopted later by the
"libre".

River and swamp fishing is done with hook and line, bow and arrow, harpoon,
cast-net, seine, dynamite, fish poison, basket trap with and without live bait, and other
methods. Each one of these requires knowledge of a special technique, which the
Negroes have learned from the Indians.





Marine fishing, although somewhat different in form and technique, involves
extensive use of similar tools and methods. Chief among these are: hook, hook and
float, hook and harpoon, feather and knife, seine, cast-net and pile.

Fishing is done from on a variety of large and small boats, mainly dugout canoes
of different widths and lengths, such as the long, narrow "piragua" and the wider
"canoa", to permit navigation of the rivers. To build them, first-class woods, such as
ceiba, chibuga, caracoli (espave), cedro, and cativo, are chosen for durability. The
specialized trade of the boat-builders permits fishing in the river network of the Atrato,
the Truando, and the Salaqul. On many canoes outboard motors are used.

The dry season is best for fishing because then fish are concentrated in diminished
water, whereas they are dispersed during the rainy season. Fishing is necessary as a
food source when it is impossible to hunt. In Santa Maria (Cuti), perhaps because of
the abundance of farm and imported products, fishing is at a minimum.

An inventory of the fish used by the Choco dweller in his daily meals includes
33 freshwater species with 17 varieties, and 27 salt water species.


Hunting. This is an indispensable element in supplementing the food supply. The
jungle is very rich in animal life in those areas where man has not hunted excessively.

The appearance of firearms has not brought about the disappearance of ancient,
primitive methods of hunting such as the use of trained dogs, traps, snares, the bow
and arrow and spear, commonly employed by Choco Indians in the area.

Jungle animals which are frequently hunted include at least 14 species of large
and small animals, and 9 species of birds.



NUTRITION AND ITS CHARACTERISTICS


Some Observations on Sampling for the Nutritional Study

The extensive dispersion of the population required making the nutritional analysis
almost exclusively in villages, where population concentration permitted a daily inven-
tory of menus for 7 consecutive days. Following are some general considerations:

The nutritional study involved 60 families in two Indian communities (Cuna and
Choco), five "libre"-Negro (including some mulattos and Chinese-Indian mixtures), and
one white colony (Cuti). In all, the dietary habits of 474 persons were studied inten-
sively.

The stratified sampling took into account such variables as ethnic condition, income
level, economic status (upper, middle, and lower classes), place of origin, education
and cultural levels. In some cases, occupations and fields of activity were also
included. In each community studied, 17 to 20 percent of the local population was
included in the sample.


7-7










7-8


Only in Salaqui were long-term data on individuals collected because the constant
mobility of the Choco families along the Salaqui and Tamboral Rivers rendered a contin-
uous study of all families impossible.


Principal Dishes in the Communities Studied

In each community, different dishes are prepared according to the season of the
year and time of Catholic "fiestas" (Christmas, New Year, Carnival, Holy Week).
Although the ingredients may be the same, methods of preparation of these dishes differ
among Negroes, Indians, and whites. Ingredients are derived from agriculture, fishing
or hunting, and imported products bought from the merchants in stores, and readily
available only to inhabitants of the principal villages. Dishes may be simple or com-
pound, depending on whether they are made of one or more products of agriculture,
fishing, or hunting, and, of course, include seasoning additives annattoo, or Bixa
orellana, salt, lard, oil, etc. ) as well as vegetables to fill in nutritional deficiencies.
In general, plantains and bananas predominate among solid foods in the diet, rice is
second, and corn, cassava, meat and fish follow (see Table 7-1). Liquid foods: milk,
chocolate, corn gruel, etc, represent at least 25 percent; fruits account largely for the
remainder.

A total of 178 compound household dishes were observed. Those based on the
three principal products of the area, plantains and bananas, corn, and rice, accounted
for the majority.

Food habits differ according to ethnic groups, as follows:

Whites and Negroes eat 105 varieties of food-a diversity explained by the fact
that these groups consist largely of immigrants from villages and towns where foreign
products and a wider range of cooking techniques are known.

The household dishes of the Indians are limited, totaling 73 for the Cuna and 22
for the Choco. These jungle groups provide their own food through agriculture, hunting,
and fishing, and seldom rely on imported products. They are more concerned with
quantity than with quality.

Fruits cannot be included in the study with accuracy because they seldom enter the
household dishes and are consumed mainly outside meal hours.


Taboos, Superstitions, and Beliefs Regarding Certain Foods

Although there has been some acculturation, all the ethnic groups in the area -
even the white colonists are influenced in their eating habits by certain taboos and
superstitions.

Among the Negroes and some mestizos, there is a wide range of beliefs, most
of which relate to women's conditions, such as: a mother, by eating eggs, can give her
baby umbilical tetanus; a mother's milk can be dried up by rubbing her breast with
camphor; if a pregnant woman sucks lemon, she cannot give birth. Others relate to
children: sweet things cause a child's spleen to grow and produce diarrhea; breadfruit
makes children agile. In general: meat is more nourishing than fish; the seeds of ripe





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plantains stick to the intestines and cause cramps; food considered "hot" causes fever to
rise. "Hot" foods include beef, pork, and peccary meat. Among foods considered
"cold", thought to cause diarrhea in children, are yuca, rice, and fruits such as banana,
orange, papaya, and avocado. Other values attached to foods by the Negro community
are: "nourishing", e. g., rice, meat, milk, and fish; "harmful", e. g., citrus fruits and
breadfruits under certain conditions; "aphrodisiacs", e.g., peccary, soft drinks, some
fish, and fruit of the calabash tree; "heavy", e. g., pork, breadfruit, and plantain;
"light", e g., brown sugar, rice, oatmeal, and corn starch.

Although these beliefs rarely have any basis in fact, they have an important
traditional influence on the people's eating habits.

Among the Choco Indians the superstitions have a magic-religious basis, which
requires that the individual attempt not to do one thing in order to avoid another. The
taboos collected refer almost entirely to women's conditions: if a nursing mother eats
papaya, guama, or boroj6, it will give the baby colic; after a woman has given birth, she
must not eat the meat of animals with teeth or fish with scales or the child's navel will
not heal; a pregnant woman should not eat plantain or ripe banana because it will produce
blotches on her face; and if she eats any sweet fruit, the embryo will grow too large for
a normal birth. A group like the Choco observes such customs regardless of the fact
that lack of certain foods may result in malnutrition.

Among the Cuna almost the same beliefs and taboos on eating are found as among
the Choco, especially for the pregnant mother.

Such customs limit the diet and can cause malnutrition to the point of health
impairment. With the influx of white colonists, their more sophisticated customs and
eating habits were introduced to the Choco and, with stock-raising, they brought milk,
cheese, and beef, enriching the limited native diets.



QUANTITATIVE CHARACTERISTICS OF NUTRITION


Three fundamental aspects of food consumption were treated in this study:
(1) predominance and proportions of each food item, (2) daily and weekly consumption
per family, by food item, and (3) intake and proportion of foods consumed by age groups
and their per capital distribution.

Alphabetical lists of foods were prepared, not based on single-food items, but
rather on dishes prepared in the home, almost always included two or more items.

Days of consumption of each food item were listed, since there is scarcely a
single food eaten on every one of the days studied. Fluctuations in consumption are
seen when special or occasional foods are eaten on religious holidays, when imported
products are sometimes eaten, and when meats of wild animals are secured through
hunting.

Consumption in grams of each food during the study period was recorded, and
certain criteria were used to obtain the net quantity of consumption per food item. For
this purpose, the following elements were taken into consideration:





In weighing foods, fruit skins, rice husks, fish scales and bones, meat bones, and
corn cobs, in fact, all materials not actually consumed were carefully removed before
weighing, to obtain the net weight.

In the volumes shown, no allowance was made for the quantity of water used in
cooking, since it becomes a part of the food, especially in soups, and it was weighed as
a part of the food intake. No effort was made to calculate the degree of evaporation of
liquids.
In recording the number of persons consuming each food item, it was noted that
not all members of a family eat at home every day, for the following reasons: nursing
infants, from 1 month to 2 years, depend entirely on mother's milk; invalids eat a
special diet; travelers and absentee family members do not participate in home food
consumption; agriculture, fishing, and hunting and, at times, business, keep them away
from home. Taboos, superstitions, customs and physiological states, especially in
women, as mentioned above, also limit the number of persons eating.

Some marginal groups, whose survival is precarious in the Choco region, often
eat only two meals a day breakfast and supper completely doing without the noon
meal, as a result of low income level and scarcity of available produce for food. Ex-
amples of such economic limitations were noted primarily among marginal communities
such as those at Arquia (Cuna), Salaqui (Choco), La Nueva, Curiche, and Coredo.
The common occurrence of alcoholism among heads of families limits possibilities
of a regular diet because income which should be used to maintain the home ends up in
village bars and stores. This reduces the volume of intake alarmingly in a large per-
centage of families.

De facto unions, or common-law marriages in the Choco, without social sanctions,
are accompanied by economic restrictions. Men incapable of supporting them may have
two or three households. Disintegration of the home is a serious cause of forced food
rationing in northwestern Colombia.
Under no circumstances do these figures apply to the stable community family;
they portray, rather, the dispersed, unstable rural family, legally and socially different
from conventional western society.
With these limitations in mind, additional charts were prepared to show actual
consumption by person and by family, and quantification of volumes which might affect
radioactive intake.

Such limitations, beyond the investigator's control, make it impossible to prepare
an exact quantitative inventory of foods available in each community under study, but
the data obtained are thought to be fairly representative. The data presented in
Table 7-1 will give the reader a rough idea of variations in the average diets of different
ethnic groups in different localities. The detailed data concerning quantities of
different foods consumed per person per day by different age groups is much too
extensive to be given here.


7-11 and 7-12


I














8-1


PAPER 8. SOILS AND AGRICULTURE OF EASTERN PANAMA
AND NORTHWESTERN COLOMBIA*

J. F. Gamble, R. Ah Chu, and J.G.A. Fiskell"'





ABSTRACT


The nuclides of interest to an agricultural ecology program, agricultural systems
in the study area and their economic importance are discussed. Several aspects of the
program which have developed special reports have been noted, four of these reports
appear elsewhere in the publication. A soils survey was conducted and certain features
are described. Characterization data for 12 soil clays are presented and their tropical
connotation discussed. The clay properties indicate soils of generally high potential
for immobilizing nuclides.




NUCLIDES OF INTEREST


In agriculture-food chain relationships, previous studies have been concerned
primarily with 90Sr, 137Cs, and 131I. Calcium and 90Sr or potassium and 137Cs have
frequently been linked. Other radioisotopes that will require evaluation in this study
are those of cerium, phosphorous, manganese, iron, tungsten, and tritium. Very
little is known of cerium and tungsten uptake in plants. Although hydrogen occurs
everywhere, it is not known whether tritium may be temporarily stored in plant com-
partments at hazardous levels, to be released when an area is cleared for planting.
The basic approach is the assumption that a radionuclide will react in a manner similar
to its stable isotope or in conjunction with a chemically similar element. Because
certain nutrient elements, such as calcium, magnesium, and potassium are frequently
present in a plant as a total amount and may replace one another, they are looked upon
as group. Ejecta will contain many stable trace nutrients that can effect changes in
uptake. Copper, zinc, manganese, or iron may not be radionuclide hazards; however,
since they are involved in metabolic reactions, they could strongly influence nuclide
uptake. It thus becomes necessary to determine stable isotope levels for all of the
essential elements in the food plants, and soils of the area, and, in addition, tungsten,
cesium, strontium, and cerium. Wherever possible, uptake studies involving either
stable isotope or radiotracer techniques have been used (Silvey thesis).








*Prepared for Battelle Memorial Institute, Columbus Laboratories, under U. S. Atomic Energy Commission, Nevada Operations
Office, Contract AT(26-1)-171.
**Soils Department, Institute of Food and Agricultural Sciences, University of Florida.











8-2


AGRICULTURAL SYSTEMS IN THE STUDY AREA


The dominant agricultural system in the study area is a subsistence agriculture
extensively employed throughout the tropics and generally known as "shifting cultivation".
As termed in this study, "shifting cultivation" describes the cultivation practices, not
the associated movements of peoples. The practice has been described in detail in the
Phase I Final Report on Agricultural Ecology (Gamble et al., 1967).

It is the forest-fallow phase of shifting cultivation that is of direct interest in this
study. The secondary growth following cropping is of particular significance as
nutrients stored in the growth are suddenly released when a plot is cleared. The
potential hazard of long-lived radioisotopes suddenly released in available form is
obvious but the effect of the forest fallow on nutrient cycling is poorly understood.
This important phase of the agricultural ecology of the study areas is covered in
Paper 9. As part of the overall environmental study elemental concentrations in the
cultivated fields will be related to their concentrations on similar soils now overgrown
with successional growth.

Other agricultural systems are also present in the study area.

Riverine agriculture is practiced where low terraces are flooded during the rainy
season, and rice, corn, or beans are planted following the flooding. The composition
of flood water and deposited river sediments are the main concerns in this type of
system. Wetland rice, which poses special ecological problems (NH4-cesium, man-
ganese exchange, possible algae relationships), was found only in limited areas of
Colombia and Panama. There are other alluvial terrace soils of agronomic importance
which are flooded once every 4 to 6 years.

Plantation agriculture is concerned primarily with coconuts and bananas or plan-
tains. There are no large companies in the study area, and the extensive plantings are
managed rather loosely. There is only one commercial copra operation in the Panama
area. Coconuts represent the major source of income to the Cuna Indians. Although
extensive,. their coconut plantings receive little management. Coconut husks are also
used as fuel in some villages. Near Turbo, located on the northern fringe of the
Colombian study area, there are modern plantations of bananas and tropical oil palms.
Coconuts have been studied in detail and the soils, yields, and compositional analysis
will be the subject of a special report (Wheeler thesis) as part of this program.
Bananas and or plantains are the main part of the diet of all ethnic groups in the study
areas. Because of the importance of coconuts and bananas (plantains), and the lack of
the radioisotope-uptake data, they were selected as the crops to be used in obtaining
some first approximations of uptake, translocation, and concentration of critical radio-
isotopes. This study is also the subject of Paper 10. There are extensive plantings of
cacao and several orchards of citrus and avocado but they do not represent a significant
export item or contribute significantly to the local diet to warrant special consideration
in the present program.

Dooryard agriculture refers to small gardens that are planted close to the houses
in many villages and to the cultigens planted close to Choco houses. The Choco gardens
have been studied previously, and we were fortunate to have Norton Nickerson review
these earlier sites and continue the study as part of the present program (Covich &
Nickerson, 1966). The particular effect of this type of agriculture on a diet analysis










8-3


is complicated by the indiscriminate additions of human, plant, and animal waste to the
gardens. The possible recycling and concentration factors are obvious.

Beef-cattle production is the major economic prospect for eastern Panama and is
the principal livestock agriculture in the study areas. Beef-cattle production is also on
the increase in Colombia. At present, the threat of hoof and mouth disease has re-
stricted herd growth and free movement of cattle in both countries. A special study of
the beef industry was made because of its potential in the economy of the area, and as
an export commodity, potential radionuclide concentrations deserve special considera-
tion. Preliminary results of this study are reported separately (Paper 11).

Milk is not commonly sold but there are some milk cows in both study areas and
cheese is produced in at least one town. Although not consumed generally, milk is
important because it is used by children, nursing mothers, and convalescents. Further,
there are no provisions for feeding stored grains or forage should fresh fallout pose a
hazardous 1311 situation in pastures. Hogs, chickens, turkeys, goats, and ducks are
also found in both areas but are not an important part of the diet or economy.



SOILS OF THE STUDY AREAS


In an environmental-radiation hazards analysis, the soil factor becomes more
important with time. After the initial excavation the direct contamination from fallout
will cease and the soil will be the source of radionuclides. To assess the potential
hazard from soil it is necessary to have a soil survey and to select principal soil types
for detailed study. Soil samples were collected with all crop samples in order to
correlate possible crop compositional variations with soil-extract analysis.

The principal agronomic soils are on recent alluvial materials. The most com-
mon colors are brown, yellowish brown, or strong brown on the Munsell 7. 5 YR and
10 YR color charts. Upland soils have the oxidized reddish brown and reds commonly
associated with tropical soils (Munsell 10 R, 2. 5 YR and 5 YR). Analyses of the
cultivated soils in both study areas indicate generally high fertility levels. The pH
values for the alluvial soils range from 6.0 to 7.2. Some have been yielding plantain
harvests for 30 years and one area in Colombia has been producing excellent corn
yields for 12 years.

There has been a previous publication on the soils of eastern Panama (Martini
et al., 1960) and one of the present authors also participated in the 1960 survey. A
reconnaissance survey of both the Panamian and Colombian study areas has been com-
pleted. Complete morphological descriptions were made of the dominant soil types
and micromonoliths were prepared as a correlation aid. Soil-extract analysis has
been conducted on the soils for the elements of interest as well as pH (2:1 water to
soil) and textural determinations on most samples.

Selected profiles have been collected for detailed analysis. The clay fraction
from the surface horizon has been separated and characterized according to:










8-4


(1) Cation exchange capacity (CEC). Determined as calcium saturation
at pH 7 after removal of MnO2, organic matter and carbonate

(2) Surface area. From ethylene glycol retention under low vacuum

(3) Amorphous material and free iron. Extracted by 0. 5N NaOH:
citrate dithionite

(4) Differential thermal analysis (DTA). Sample 0. 150 gram of clay
dried at 40 C in fired asbestos (The endothermal areas were deter-
mined in the region of 50-250 C [ LR] and 500-700 C [MR]. Georgia-
kaolin has an MR value of 44. Chlorite presence is tested by heat
treatment at 600 C. )

(5) X-ray diffraction analysis (XRD) (Diffractograms were prepared
using Mg-saturated, glycerol-solvated clays.).

Clay properties of 12 of these soils are presented in Table 8-1. The clay
properties clearly reflect the tropical nature of the soils. Although the color, texture,
and structure of the soils are similar to many temperate-zone soils, the high CEC
values coupled with a very high surface area, high percentage of amorphous material
and interlayered montmorillonite-halloysite are clearly tropical in nature. The inter-
layering is such that crystallinity is sometimes obscured and only quartz can be easily
identified. No chlorite or vermiculite was present in any of the samples.

TABLE 8-1. PROPERTIES OF CLAY FRACTION OF 12 PANAMA SOILS

Surface Amorphous Free
Sample CEC, Area, Clay, Iron, DTA
Location(a) me/100 gm m2/g percent percent LR MR XRD Pattern(b)
Rio Iglesias 91 460 45 2.6 10 4 Qtz
Santa Fe 169 1010 54 2.5 63 40 st IMH
Yaviza 74 640 23 4.3 70 22 st IMH
Rio Balsas 105 635 4 6. 1 26 27 st IHM
Mulatupu 80 570 6 7.4 10 5 m IMH, w IHM
Sasardi 56 216 22 10.8 10 43 m IHM, st H
Sambu Valley 56 578 23 7. 1 36 22 IHM
Morti Abajo 111 635 15 3.7 25 24 Qtz
Santa Fe 96 575 17 2.8 24 29 st IMH
Patino 54 318 13 3.7 15 13 st IHM
Trocha 150 1030 21 1.6 28 15 st IMH
Uala 60 755 30 7.9 53 34 st IMH

(a) Samples 1 through 6 represent principal soil types.
(b) IMH interlayered montmorillonite-halloysite
IHM interlayered halloysite-montmorillonite
Qtz quartz
st strong; w weak; m moderate.


To further assess their potential for nuclide retention, a radiotracer experiment
was conducted. Six nuclides were compared in pairs: 59Fe-54Mn; 86Rb-137Cs;
45Ca-89Sr (Paper 12).

















I


Table 8-2 presents elemental analyses determined on soil extracts obtained using
neutral ammonium acetate as the extracting agent. The only latosol (oxisol) in the
group is the Sasardi soil and the analysis is strikingly different from the others. The
Mulatupu sample is an alluvium soil on the Atlantic coast in the drainage agea of the
Sasardi soil. The Trocha soil is located on the black shales near Santa Fe on the
Pacific side of the proposed Panama route. The two Santa Fe soils reflect some of the
differences that are to be expected in soils developed in mixed sediments of calcareous
shales and sandstones that have been reworked by flood waters. The other soils are
developed on alluvium in the interior of the study area. Yaviza is in the center of a
large plantain-producing area. There are some significant differences in the elemental
composition of the extracts from these Entisol Orthents but it is readily apparent that
they have a high natural fertility status. The high levels of nutrient elements in the soil
extracts corroborates the clay-characterization data and indicates that soluble-cation
losses by leaching are very low.



REFERENCES


(1) Covich, A. P. and Nickerson, N. H. 1966. Studies of cultivated plants in Choco
dwelling clearings, Darien, Panama. Econ. Bot. 20:285-301.

(2) Gamble, J. F., Popenoe, H. L., and Associates. 1967. Phase I Final Report,
Agricultural Ecology. BMI-171-010.

(3) Martini, J. A., Ah Chu, R., Lezcano, P. N., and J. W. Brown. 1960. Forest
soils of Darien Province, Panama. Tropical Woods 112 (Nov.): 28-39.

(4) Silvey, M. W., Ph.D. Thesis, University of Florida, in preparation.


(5) Wheeler, G. L., M.S. Thesis, The University of Florida, 1968.


8-5














8-6


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9-1


PAPER 9. COMPOSITIONAL ANALYSIS OF SELECTED
SECOND-GROWTH SPECIES FROM
LOWLAND GUATEMALA AND PANAMA*

Samuel C. Snedaker and John F. Gamble" `


ABSTRACT


Mineral elements immobilized in the second-growth fallow vegetation
of the shifting agriculture cycle are released to the soil when the vegetation
is cut (and burned) prior to cropping. Twenty-one species, characteristic
of various fallow stages, were sampled in Guatemala and Panama for com-
positional analysis. The results for eleven elements show variation both
within and among species. Additional analyses, in progress, are needed to
determine crop nutrient availability for varying fallow conditions.



The subsistence agriculture along the proposed sea-level-canal routes in Panama
and Colombia, and the study area in eastern Guatemala, is commonly called "shifting
agriculture" and exists in two forms, slash-burn and slash-mulch (Gamble, et al.,
1967). Both forms involve intervening fallow periods between cropping sequences, and
the duration of the fallow is determined by an interaction of environmental and cultural
factors. Before crop yields begin to drop off and/or weeds and crop pests become a
burdensome problem to the agriculturist, the field is abandoned and allowed to lie in
forest fallow while another area is cleared for cropping.

In addition to being regarded as a beneficial soil management practice, the fallow
also allows for the elimination of weeds and crop pests while the regenerating vegeta-
tion immobilizes certain mineral nutrients. .. Burning (or mulching) of the fallow
vegetation releases most of the more-mobile mineral nutrients to the soil subsequent
to planting the site.

In studying the shifting agriculture cycle, various workers have made composi-
tional analysis of the second-growth fallow vegetation (Gamble, et al., 1967), but little
effort has been made to determine the composition of the individual species comprising
that vegetation. Nye (1958) determined amounts of plant nutrients in individual species,
but only for five elements, and limited his selection to the main woody species in differ-
ent ecological zones in Ghana.

Data collected from a series of fallows of known ages in the Lake Izabal area of
Guatemala indicate three major changes in the floristic composition during the first 10
years of forest regeneration after abandonment. The first change occurs during the
first or second year when the primarily short-lived, herbaceous species present at the
time of abandonment are eliminated by vigorous coppice growth and an assortment of
woody species. Most of the latter are soft-wooded trees, such as Bursera, Ochroma,
Cecropia and Cochlospermum, which become dominant around the fourth year. They

*Prepared for Battelle Memorial Institute, Columbus Laboratories, under U. S. Atomic Energy Commission, Nevada Operations
Office, Contract AT(26-1)-171.
**Institute of Food and Agricultural Sciences, University of Florida.


***The term "mineral nutrient" is used without regard to a known role or requirement in plants.











9-2


persist until species characteristic of late secondary forests begin to assume increasing
dominance. The exact time when the second and third changes occur depends primarily
upon the proximity of seed sources which itself appears to be a function of the intensity
of the shifting agriculture cycle.

The quantity of mineral nutrients released to the soil when the fallow is cut and
burned (or mulched) preparatory to cropping is then, in part, a function of the floristic
composition as it changes with age. Generally, in the Darien (Panama), fallow is cut
after as short a period as 4 or 6 years, whereas in the Lake Izabal area of Guatemala
it may be left for 8 to 15 years. The length of the fallow period between successive
cropping on the same site depends primarily upon site quality and population pressure.

As a part of the agricultural-ecology study, samples of second-growth species
and soils were collected in Panama and analyzed to determine the concentrations of 11
elements. These data will be useful in making preliminary estimates of the quantities
of radionuclides that could be accumulated by second-growth vegetation during the
period of nuclear excavation and thus become available for uptake by post-excavation
crops planted in the same fields. The similarity of agricultural systems and of second-
growth flora in the two areas studied may permit the Guatemalan data to be used for the
same purpose.

The data presented in Tables 9-1 and 9-2 represent a compilation of the results
of four independent samplings and analyses. The data of Popenoe are from samples
taken at Finca Los Murcielagos, Guatemala, in 1962. Those of Ewel and Snedaker are
from samples collected at the same location in May and July of 1966, respectively.
Gamble's samples were collected from three locations in Panama (listed in the tables)
during February and March, 1967. At the same time the plant tissues samples were
taken by Snedaker and Gamble, corresponding soil samples were collected from various
horizons. These data correspond to the tissue-sample data which bear the same
vegetation age or location as listed.

The herbarium at the University of Florida identified the plant specimens and has
retained voucher sheets. Specimen number E-190 is an unidentified arboreal legume.

The data show a marked variation in mineral-nutrient composition, both within
and among species. Aside from the error normally associated with analytical proce-
dures, the within-species variation is due to several factors in addition to the fertility
of the soil in which they grew. It is commonly known that foliar -nutrient content varies
with a multitude of environmental and genetic factors. Within a species, analytical
results vary according to season, the time of day of sampling, the specific tissues
sampled, and the subsequent handling of the samples prior to analysis. Each of these
factors may differentially influence each nutrient. The compositional analysis of
Heliconia latispatha is to some extent illustrative of this variation. Samples collected
varied only in the time of sampling, yet there is a notable difference in the concentra-
tions of nitrogen, phosphorus, potassium, and iron. Analyses of other species show
similar variation in the mineral-nutrient content.

The high magnesium concentrations in the Guatemala-tissue analysis reflect the
unusually high magnesium-calcium in the soil. Tergas (1965) found similar relationship
in his study of mineral-nutrient availability in soil and uptake by fallow vegetation in the
same area. These ratios are unusual in most soils, but are typical of soils derived
from serpentine materials.

















9-3







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Although the work is presently incomplete, the data show the general composition
of mineral nutrients which might be expected to be found in second-growth species.
The small sample size of each species limits, at this time, a thorough interpretation
of among-species and within-species variation and relationship to soil.



REFERENCES


(1) Ewel, J. J., unpublished data.

(2) Gamble, J. F., Popenoe, H. L., and Associates. 1967. Phase I Final Report,
Agricultural Ecology. BMI-171-010.

(3) Nye, P. H. 1958. The Mineral Composition of Some Shrubs and Trees in Ghana.
J. West African Sci. Assoc., 4:91-98.

(4) Popenoe, H. L., unpublished data.

(5) Tergas, L. E. 1965. Correlation of Nutrient Availability in Soil and Uptake by
Native Vegetation in the Humid Tropics. M.S. Thesis, University of Florida,
Gainesville.





PAPER 10. UPTAKE AND TRANSLOCATION OF 134Cs, 59Fe,
85Sr, AND 185W BY BANANA PLANTS AND A COCONUT
PLANT FOLLOWING FOLIAR APPLICATION*:-

W. Neill Thomas son'**
W. Emmett Bolch-**
J. F. Gamble***


ABSTRACT


This paper discusses the methodology of performing an environmental tracer
experiment on tropical fruit. The objective was to measure the uptake and translocation
of tungsten, strontium, cesium, and iron, using radiotracers. Some of the results are
also presented briefly.



OBJECTIVES


The overall objective of this project was to gain some insight into the ecology and
uptake relationships of several important radionuclides in selected tropical fruits.

Samples of food crops and milk were collected in the Panamanian and Colombian
study areas and analyzed by gamma-ray spectrometry for existing levels of radioactivity.
The current environmental levels are too low to formulate an approximation of specific-
activity relationships or uptake factors relative to the stable-isotope compositional
analyses. It was not possible to introduce radiotracers into the uptake experiment con-
ducted in the Panama study area. Therefore, the facilities of the University of Florida's
Sub-Tropical Experiment Station at Homestead, Florida, and the U.S.D.A. Plant Intro-
duction Station were utilized to obtain some information on uptake of critical radionu-
clides in tropical food plants. The radionuclides used in this study were 185W, 85Sn,
134Cs, and 59Fe.

The banana (genetically similar to plantain) was selected for the study because it
represents a sizable portion of the diet of all ethnic groups in the study areas, and the
coconut because it is a major economic crop of the Cuna Indians. There are some
radioisotope uptake data for the other major food crops, rice and corn, but no data are
available for banana and coconuts. The specific objectives of the study were (1) to
develop the field methodology for performing environmental tracer experiments while
maintaining control of the tracers, (2) to determine laboratory procedures for the
quantification of environmental samples containing a complex mixture of radionuclides,
and (3) to investigate the transport and metabolism of radionuclides applied to the foliage
of the banana and coconut.

*Prepared for Battelle Memorial Institute, Columbus Laboratories, under U. S. Atomic Energy Commission, Nevada Operations
Office, Contract AT(26 -1)-171.
*Environmental Engineering, University of Florida.
***Institute of Food and Agricultural Sciences, University of Florida.


10-1










10-2


METHODOLOGY


Two environmental experiments were conducted. The differential uptake study
involving mixed radionuclides was performed over a 17-day period in early November,
1967. From a small grove on the main station, a Malaysian dwarf coconut palm of the
yellow variety with a balanced distribution of maturing fruit was selected. A banana
plant was selected that had fruit approximately 3 weeks from maturity. The sites were
prepared by removing all vegetation beneath the test trees, placing plastic sheeting out
to a sufficient radius to intercept all runoff from the treated fronds and finally covering
the plastic sheeting with 3 to 4 inches of peat moss. Background samples of fruit and
foliage were collected from other trees in the area.

Soluble forms of carrier-free 185W, 85Sr, 134Cs, and 59Fe were applied to the
fronds of the coconut palm and the leaves of the banana tree. The NaEDTA solution,
applied with a paint brush, contained equal concentrations (4 piCi/ml) of each isotope.
Three coconut fronds and four banana leaves were treated with a total of 100 ml and 50
ml, respectively. This represented approximately 10 and 30 percent of the total foliar
area available in the coconut and banana trees, respectively. A security fence enclosed
each test site, and radiation warning signs were posted.

Seventeen days after application of the radioisotopes, the peat moss and plastic
were removed for disposal, and the area was surveyed. Expect for minor break-
throughs, most of the activity not absorbed by the plants was confined to the peat and
plastic. Removal of a small quantity of soil restored the area to a level of only twice
the natural background.

All tissue samples were processed to a homogeneous state using a food blender.
They were placed in an 800-ml plastic counting container for analysis by gamma-ray
spectrometry using a 4 by 4-inch right-cylinder, sodium iodide (Th), scintillation
crystal and 400-channel pulse-height analyzer in a large tri-component shield, housed
in a large, low-level equations.

Figure 10-1 is indicative of the types of spectra used to calibrate the instrumenta-
tion. The spectrometry data were analyzed by an IBM 360 computer using a matrix of
simultaneous equations.

Stable concentrations of calcium, iron, manganese, cesium, potassium, magne-
sium, strontium, phosphorus, zinc, and copper were determined in leaf, fruit, stems,
and soil-extract solutions. These data will be used to compare the Florida experiments
with those on samples collected along the proposed canal routes.

The second field experiment was conducted from May 10, 1968, to June 5, 1968, at
the United States Department of Agriculture's Plant Introduction Station, Miami, Florida.
This site is suitable for long-term studies with greater control of the test area. In this
study, three dwarf banana plants were treated with a 134Cs tracer solution containing
4 1LCi/ml to determine the kinetics of cesium metabolism by the plant. Cesium was
selected as the tracer because of its rapid uptake and translocation during the first
banana experiment. Selective sampling of the bananas as a function of time was accom-
plished by collecting five bananas every other day for 10 days, and collecting a final sam-
ple after 26 days. The application technique was basically the same as in the previous














10-3


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study except for improved techniques including the use of continuous feed applicators and
the use of a leaf punch to sample activity on the leaves at various times.



RESULTS


The computer analysis of the data from the mixed-nuclide experiment has been
completed. There was high selectivity for cesium over the other three radionuclides in
the banana and coconut plants. There was greater translocation in the banana plant than
in the coconut by at least an order of magnitude. In fact, cesium exhibited measurable
movement to adjacent plants (not of a common clone) some 15 to 20 feet away. There
was slight but measurable concentration of 185W in the banana peels of the fruit of the
treated tree, as well as the peels of fruit from adjacent trees; however, no 185W was
found in the fruit. New young leaves above the treated ones contained all of the radio-
tracers used, but 134Cs was by far the most dominant. Leaves of a new sword sucker
of the treated plant also indicated 85Sr and 59Fe along with large amounts of 134Cs.

There was much less translocation of 134Cs to the fruit of the coconut tree. Small
amounts of 185W, 85Sr, and 59Fe were translocated to untreated fronds above and on the
opposite side of the palm from the treated fronds. The only radionuclide detected in any
part of the fruit was 134Cs which was also detected in the fruit of palm trees on either
side of the treated tree.

The sensitivity for tungsten was greatly improved by use of a selective-
precipitation technique developed in this study, which uses a sodium tungstate carrier
and cinchonine, a tungsten completing agent. Ninety-three percent separation of pre-
pared tungsten standards was achieved using the above procedure.

The results of the kinetic study are shown in Figures 10-2 through 10-4, where
Ct/Ce is the ratio of the concentration at the time indicated to the equilibrium concentra-
tion. The fruit of the three trees ranged from very young (Tree 2) to mature (Tree 3).
Tree 1 had fruit approximately two-thirds mature. The inflorescence of Tree 2 had
failed to emerge from the axial of the stem. The rates of uptake of Tree 1 and Tree 3
were the same. Tree 2 had a slightly higher rate of uptake, but this was expected since
the younger fruit should have a higher rate of metabolism. Since the inflorescence had
not emerged properly from the axial and the bananas were developing in the axial, it is
believed this resulted in higher amounts of uptakes due to channeling the radiotracer into
the inflorescence than would otherwise have been the case. While Tree 1 and Tree 3 had
the same rate constant, their equilibrium-concentration values were very different.
Approximately the same amount of activity was applied to both trees, though Tree 3 had
a larger surface area covered.

The influence of rain was clearly shown in both experiments. There was a 1. 5-
inch rainfall within an hour of treating the coconut palm. Though twice as much tracer
solution was applied, the activity on the treated coconut fronds at the time of sampling
was much less than on the banana leaves. The kinetics experiment provided an even
greater illustration of the effect of rain on the amount translocated. Tree 1 was treated
when no rain was falling. Treatment of Tree 2 was during a light rain, and by the time
Tree 3 was treated, a regular downpour was in progress. The equilibrium constants in
the models show the effect of the rain. The constants were 2400 cpm, 4820 cpm, and


10-5










10-6


750 cpm for Tree 1, Tree 2, and Tree 3, respectively. While about 16 percent more
activity was applied to Tree 1 than the other trees, Tree 2 had more activity translocated
to the fruit. The difference in the equilibrium constants was the effect of the loss of
activity by the washing of the rain. As in the first experiment, washed-off activity was
confined to the peat on the plastic. Because of the large amount of rain, the peat and
plastic were changed after 10 days and fresh peat and plastic spread for the next 16 days.
The concentration of mixed radiotracers applied to the plants yielded sample activities
that were considerably above the minimum detectable activity of the low-level analyzer
system used; however, concentration techniques were needed to determine certain
radionuclide s.



SUMMARY


The study has demonstrated the feasibility of conducting environmental tracer
experiments. For a given amount of effort, one has the alternatives of either (1) green-
house experiments with a highly artificial environment, but with more statistical con-
trol, or (2) field experiments under natural conditions, but with minimal statistical
design. The investigators feel the latter choice has considerable merit. Further con-
clusions on uptake and translocation kinetics, selectivity coefficients, relative specific
activities at equilibrium, and other ecological factors will be drawn after complete
analysis of the results.





PAPER 11. COMPOSITIONAL ANALYSES OF SOILS, FORAGES, AND CATTLE
TISSUES FROM BEEF PRODUCING AREAS OF EASTERN PANAMA*

W. G. Blue, C. B. Ammerman, J. M. Loaiza, and J. F. Gamble**


ABSTRACT


Elemental compositional analyses are presented for total soil contents and soil
extracts, grass and legume forages, and beef cattle tissues collected in Eastern
Panama. Samples were analyzed for calcium, strontium, potassium, magnesium,
sodium, zinc, copper, iron, manganese, nitrogen, and phosphorous. Concentrations
of most elements are discussed and outstanding features are noted. There are distinct
differences in bone strontium concentrations between two locations in Eastern Panama
and a sample from Western Panama yielded a third level of concentration.


INTRODUCTION


Plans for a detailed study of the beef industry in Eastern Panama were formulated
during a reconnaissance of the area in February of 1967 (Gamble et al, 1967). Uncer-
tain slaughtering schedules and vague shipping times combined to make impossible a
complete sampling of soils, forage, and beef fed on the forage. Surface soils (0-15 cm)
and forage samples were collected from four ranches in the general vicinity of the pro-
posed sea-level-canal route in Panama. The ranches were located at Yaviza, Santa Fe,
El Real, and Pati~io. Animal tissue samples were obtained from El Real, Santa Fe, and
from animals that had been raised near David in Western Panama.


SOIL ANALYSES


Soils were obtained from pastures on well-drained and poorly drained alluvial
deposits, high terraces, uplands, and old beach deposits. They generally were fine
textured with the exception of two from the beach area near Patinio. Average analytical
values (Table 11-1) show that the soils were well supplied with organic matter all
samples contained in excess of 4. 0 percent except for two Patinio sands which contained
approximately 3. 0 percent. Total soil nitrogen ranged from about 2500 to more than
5000 ppm except for the two sandy soils. The carbon-nitrogen ratio ranged from 8. 0
to slightly above 11. 0. Soil pH was above 5. 5 in most cases and ammonium acetate
(pH 4. 8) extractable calcium and magnesium generally were high calcium 2400 to
12000 ppm and magnesium, 700 to 1600 ppm. Most soils were relatively well supplied
with total phosphorus: 375 to 1175 ppm. Those from Patiiio were lowest, and two of
the upland oxisols contained only 374 ppm. Ammonium acetate (pH 4. 8) extractable
phosphorus was low in most cases, which is normal for these latitudes. In spite of the
relatively high total phosphorus, our experience with similar soils in Costa Rica and
other Central American countries indicates that they will probably respond to fertilizer
phosphorus (Andrade et al., 1964). Ammonium acetate extractable potassium was also
*Prepared for Battelle Memorial Institute, Columbus Laboratories, under U. S. Atomic Energy Commission, Nevada Operations
Office, Contract AT(26-1)-171.
**Institute of Food and Agricultural Sciences, University of Florida, Gainesville, Florida.


11-1























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in phosphorus); these two contained only 131 and 158 ppm potassium.


FORAGE ANALYSES

Grass forages and an associated legume were collected from each ranch in asso-
ciation with soil samples. Grasses were jaragua (Hyparrhenia rufa), guinea (Panicum
maximum), para (Panicum purpurascens), and pangola (Digitaria decumbens). The
legume was a Desmodium species in each case. These were analyzed for nitrogen,
phosphorus, potassium, calcium, magnesium, strontium, zinc, manganese, iron, and
cesium (Table 11-2). The nitrogen content of grasses did not indicate serious defi-
ciency; values ranged from slightly less than 1 to slightly more than 2. 0 percent on an
oven-dry basis (70 C). The forages were relatively young at sampling time since the
annual rainy season had begun only a month before. Based on previous data from Costa
Rica, these forages, as they mature, will become deficient in nitrogen for plant growth
and animal performance. Nitrogen is most available at the beginning of the rainy sea-
son. Sustained high forage production will necessitate use of nitrogen fertilizer or
preferably the introduction of productive legumes. The legume contained from 2.4 to
3.4 percent nitrogen. The analyses, plus visual nodule observations, indicate effi-
cient symbiotic nitrogen fixation. Plant phosphorus concentrations appeared normal
with both grasses and the legume containing between 0. 2 and 0.4 percent. Potassium
also did not appear to be particularly deficient in any samples. An interesting and
practical observation was the high potassium content of guineagrass. This grass con-
tained from 3.3 to 5. 5 percent potassium. When grass production begins following
initiation of the rainy season, cattle scour badly. High salt concentration, such as
found in this grass, would accentuate the problem. The calcium content of the grass
forage ranged from 0.20 to 0.40 percent and magnesium from 0. 10 to 0.30 percent.
The Desmodium contained between 1. 14 and 1.70 percent calcium and 0.20 and 0.40
percent magnesium. Strontium concentrations ranged from 14 to 100 ppm and cesium
levels were not detectable at the lower limit of detection (12 ppm). Abnormally high
manganese and iron concentrations were found in two paragrass samples and the assoc-
iated legume growing on poorly drained areas at Yaviza and El Real.

An opportunity was provided at Patino to secure dry jaraguagrass forage from a
pasture. This forage had been produced the previous year and had been exposed to the
rigors of the dry season. Analyses showed that forage concentrations of all major
nutrients except calcium were extremely low and substantially less than cattle require-
ments. These data are in accord with those obtained by Andrade et al. (1964) from
the alternately wet and dry Pacific region of Costa Rica and by Tergas (1968) in the
same area. It is strongly suspected that reduced forage-nutrient concentrations under
these conditions result from their translocation from the plant tops to the roots due to
severe moisture stress.


11-3


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CATTLE-TISSUE ANALYSES


Fourteen mature Brahman cows ranging in age from 3 to approximately 9 years
of age were sampled from the El Real areas and nineteen Charolais X Brahman cross-
bred steers and one bull of similar breeding ranging in age from 2 to 3 years were
sampled from the Patino area. Most of the cows were culled from the herd because
they were not pregnant and were slaughtered one or two at a time for the local market.
Tissue samples were also collected from ten Brahman steers from David at the
Panama City slaughterhouse. Essentially, the entire diet of all cattle had consisted of
pasture forage although apparently some supplemental mineral had been fed. The tis-
sue samples taken included the right metacarpal, and samples of liver, kidney, heart
(left ventricle), spleen, and muscle. Calcium, phosphorus, sodium,potassium, manga-
nese, magnesium, zinc, copper, iron, and strontium were determined for each
sample.

The average element concentrations for the tissue samples are shown in Table
11-3. In general, the elemental concentration of the soft tissues expressed on a dry-
matter basis did not differ greatly between locations as represented by the different
types of cattle. Magnesium levels varied from 600 to 1270 ppm in tissue with the heart
tissue having the highest and the liver the lowest concentration. Manganese varied
from about 2 to 6 ppm with the muscle being the lowest followed in turn by the spleen,
heart, kidney, and liver. Potassium values were highest in the spleen (17, 000 ppm)
with values for the other tissues ranging from 10, 000 to 12, 000 ppm. In general, zinc
levels were highest in the liver (160 ppm) and lowest in the heart (97 ppm). The levels
of copper in tissues of all cattle from El Real were uniformly lower than those from
cattle of the Patino area. The iron concentration of the spleens from the El Real
cattle was higher than that of Patinio cattle, suggesting an inability to use iron for
hematopoiesis due to a shortage of copper.

The elemental concentrations in the metacarpal bone ash appeared similar for all
elements except for iron and strontium. The bone ash for cattle for El Real contained
35 ppm iron compared with 10 and 13.5 ppm from Patino and David, respectively.
There are large differences in the bone strontium concentration with a ratio of 1:3:10
among El Real, Pati~io, and David. El Real soils are similar. The soils from the
Eastern Panama sites are different, but their strontium concentrations are not ex-
tremely varied, and the forage analyses are similar. The differences appear real and
may reflect the forage diet; the El Real cattle have more paragrass pasture than the
Patino cattle.


REFERENCES


Andrade, J. L., G. E. Rey, M. T. Ramirez, Ch. A. Carillo and W. G. Blue. 1964.
Fertilizer response and dry season changes in forage grasses in the Pacific Region of
Costa Rica. Trop. Agric. 41: 31-39.

Gamble, J. F., H. Popenoe and Associates. 1967. Phase I Final Report
Agricultural Ecology. Battelle Memorial Institute, Columbus, Ohio.

Tergas, L. E. 1968. The effect of nitrogen fertilization on the movement of nutrients
from a tropical grass under soil moisture stress in a hot savanna. Ph.D. Thesis.


University of Florida. Gainesville, Florida.
















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