Symposium on sea-level canal bioenvironmental studies

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Symposium on sea-level canal bioenvironmental studies
Series Title:
Bioenvironmental and radiological-safety feasibility studies : Atlantic-Pacific Interoceanic canal
Martin, William E.
Battelle Memorial Institute
Publication Date:


Subjects / Keywords:
Caribbean ( LCSH )
Panama Canal
Spatial Coverage:
North America -- Panama -- Panama Canal Zone

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Full Text




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

Columbus Laboratories
505 King Avenue
Columbus, Ohio 43201




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

Columbus Laboratories 505 King Avenue
Columbus, Ohio 43201



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

Paper 2. James R. Vogt: Radionuclide Production for the Nuclear
Excavation of an Isthmian Canal. .2-1

Paper 3. Gilbert J. Ferber and Robert J. List: Prediction of External
Gamma Dose from Nuclear Excavation of a Sea-Level Canal 3-1

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. .4-1

Paper 5. P. S. Rohwer and S. V. Kaye: Predicting Radiation Dose
Equivalents for Populations: II. Results Obtained with the
Dose Models. 5-1

Paper 6. Reina Torres de Araiuz: Demographic and Dietary Data for
Human Groups Inhabiting the Eastern Region of the Republic
of Panama. .6-1

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, 855r, 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.









R. L. Charnell, T. M. Zorich, and D. E. Holly: Hydrologic Redistribution of Radionuclide s 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 SpecificActivity Approach 0 00a09 &0a0

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 0 a 0 0 . 0 9 0 . & . 0 6 . 0 0 0

Pape r 15. Pape r 16.

Pape r 17. Paper 18. Pape r 19. Pape r 2 0.




018- 1

0 019-1




Battelle Memorial Institute, as a major contractor to the U. S.- Atomic Energy
Commission, Nevada Operations Office, has been responsible for the technical management of environmental 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 sealevel canal routes, extensive field studies of human, agricultural, terrestrial, freshwater, 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 environmental 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 ecological 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.


William E. Martin"'


This is the first of ZO articles that will be published in BioScience to summarize the contents of a Symposium on Sea-Level Canal B io environmental 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 bio environmental 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.


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 radioactive 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 reasonable 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 commercial 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.
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*Studies supported by U. S. Atomic Energy Commission, Nevada Operations Office, Contract AT(26 -1) -17 1.
**Battelle Memorial Institute, Columbus Laboratories, Columbus, Ohio.



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 pos sible 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-Truand ". route in Colombia (Figure I1-1), 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 authorized them "to make a full and complete investigation and study, including necessary on-site surveys and considering national defense, foreign relations, intercoastal shipping, interoceanic shipping, and such other matters as they may determine to be important, 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 bio environmental 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 feasibility of the nuclear -excavation plan and the plan for conversion of the present canal to sealevel operation by conventional methods. For the nuclear -excavation plan, detailed information concerning topography and geology is required to determine the precise spacing, depth, and yield of nuclear devices needed to obtain the desired canal configuration and to evaluate other problems such as slope stability and conventional construction 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 structures might be needed to control tidal currents near the ends of the canal. Studies related 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-r Iange transmission and ducting of acoustic waves have



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


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 radiologicalsafety 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 determining 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 segment 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 distribution 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 bioenvironment: 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



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)


The subscript i indicates the dependence of dose on a particular radionuclide in a particular 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 necessary 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 series. Predictions of the patterns of local fallout and the potential external gammaexposure 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 radionuclides 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 internal dose.

The dose-commitment term, Ci, has been evaluated for more than 100 radionuclides 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 tj 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.


given radionuclide may enter the diet by many different pathways. Evaluation of the important 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 models 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 concerning the demography, the dietary habits, and the subsistence economy of the indigenous 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 potentially 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 associated 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 bioenvironments, on which they depend for subsistence, but they have not provided all the information required to estimate potential radiation doses by means of the most realistic methods 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 radionuclide 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 influenced by a great many considerations that have nothing to do with radiological safety



James R. Vogt"**


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 radionuclide production and distribution are described along with some recent nuclear experiments conducted by the U. S. Atomic Energy Commission to provide technical data on cratering mechanisms and special emplacement techniques which could minimize the release 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.


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.


*Studies supported by U. S. Atomic Energy Commission, Nevada Operations Office, Contract AT(26 -1)-ill1. "Battelle Memorial Institute, Columbus Laboratories, Columbus, Ohio.


scavenging during the cratering process, and the utilization of minimum-fission explosives. 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 experiment 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 explosions. 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 Cab riolet 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 proposed isthmian canal. Characteristics of the family of nuclear explosives proposed for construction of a s ea -level canal are given in Table 2 -1.


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-tofusion 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 4n
55Mn, 55Fe, 59Fe, 185W,) 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,) 45 Ca, 56Mn, 55Fe, and 59Fe.)

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



Number of Devices Total Yield, megatons Yield of Largest Detonation, megatons Largest Device, megatons Number of Detonations Length, mile s

17A 25A
437 223

274.8 245. 1

30. 0 10.0



30.0 10. 0 19


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

TABLE 2-2.


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) I kiloton 10- megaton.


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, a), (n, Zn), and
(np) reactions, are of less importance in the production of neutron-induced activities in the rock.


For most of the radionuclides released during a catering detonation, a large fraction of the activity will be distributed in the fallback and throwout material. The fraction 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 s he ' ar, 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 areal 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 employing extensive neutron shielding. Based on reasonable assumptions about these factors, the following information can be used in planning for catering events of useful magnitude. For each individual nuclear explosive detonated, the sum of fission products airborne in the radioactive cloud and in the fallout can be expected to be as low as the equivalent of ZO tons. The tritium release may be less than 20 kilocuries per kiloton 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 Z-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 ZO 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 Z-4.

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

TABLE 2-4.


Nuclide Half-Life Kilocuries Per Device

90Sr 28 years 0. 001
137Cs 30 years 0. 004

106Ru1 year 0.08

89Sr 50 days 0. 2
144Ce 284 days 0. 07

9ly 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

2-5 and 2-6

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



Gilbert J. Ferber"""
Robert J. List


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,


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.


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,


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 catering detonation typically consists of a
central column, or 11main 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 catering 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 catering 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 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



Next, we will consider the radioactivity which would be deposited from the debris clouds. In order to minirni ze 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 Col'ombia 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,

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 uncertainties 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 catering 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 catering detonation conducted to date. The average fraction deposited per hour is shown in Table 3-1 for a cloud rising to 1Z, 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.


Time Interval, Fraction of Local
hour s Fallout Deposited

0-0. 5 0.66
0.5-1.0 0.17



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.


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





Figure 3-3 shows a lifetime-dose pattern when people reenter the exclusion area I 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).

2 0 . .

a- 15
20,000 FT.
10__ . .
30,000 FT.
40.000 FT.
XXXX . . . .
50,000 FT.
5 -- .
. . . . . . . . . . . . . . . . . .
. .
. . . . . . . . . . . .
L ) . . .
. . . . . . . . . . . . . . . . . . . . . .


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 catering experiments, we may find that detonations could be conducted on many days which are now classified as unfavorable,


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,


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.



S. V. Kaye, P. S. Rohwer, K. E. Cowser, and W. S. Snyderll lf%


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.


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 requires biological data for adults, children of all ages, and even for fetuses. Agedependent considerations make the problem more complex than when only the parameters 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


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.


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

Most data on production and venting for nuclear catering 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 catering 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 inventory 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 submersion in the over-passing radioactive cloud, submersion in contaminated water, and exposure to a contaminated landscape. Internal radiation doses are estimated with a

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


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 QiCi) 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 assimilation fractions (all as a function of age). The following section describes our attempt to include these age dependent parameters in internal dosimetry models.


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 equation represents our attempt to incorporate the essential information into one expression for estimating internal dose:


Dijkl tz, t; Y(t)]=Qij � P ik(t) Cij ILY(t), t-t] dt (rem),(1 tl

wher e

Dijkl tl, t2, 'Y(t9] 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 -N(tl) at tl,

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

Pijk(t) = concentration of radionuclide i in pathway j at location k at time t per unit of radionuclide initially available (uCi/g per gCi released), and

concentration will have to be estimated with systems -analysis techniques.



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 primary 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 I2E(S-t Din (tl, t2, tb) - 51� i[(t-tb), t]fin(ttb) � mn(s-tb) ti ti

s -tb
exp[ -5 Xin(y)d-]ds} dt (rem), (2)

t- tb


Din(ti, t2, tb) - Cumulative dose equivalent (rem) received during the time interval ti to t. 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,

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

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

t - time (days) after reference detonation,

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

Ii(t) - intake (QiCi/day) of ith radionuclide during a unit time pe riod t,

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

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

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

in(t) = effective elimination constant (days-') of the ith radionuclide in the nth organ at t.

The variables tl, t2, tb, t, and s are measuredrelative to a reference detonation; whereas the variables li(t), mn(t), fin(t), cin(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 three modes of exposure considered in estimating external dose are: (1) submersion in the radioactive cloud, (2) submersion in contaminated water, and (3) exposure 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 pathway, has been programmed for estimating dose equivalents from external exposure:

tZ N' _Xri(tTn)

Dikq(tl, tz, x) = 5 I Qinqe Pikn(X)Ciq(x)dt (rem), (3)
tI n=1


Dikq(t, t2, 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 Ito 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,



N I = maximum (n) such that Trn -<-,t, N I <.,N,

Tfl = time (hours) of the nth detonation,

Qiq= quantity (bLCi) of the qth particle or photon of radionuclide i released from the nth detonation,

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

Pikn = lo cation 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 (q1l) or photons (q=?,) 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 substituted for the term Ciq(x). All of the dose-rate equations used in the EXREM code are listed and explained in the IJSAEC 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 falloutprediction models and systems -analysis techniques.


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 considered 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


(1) Radionuclide Dose Equivalent List (RDEL) - An ordered arrangement of
radionuclides according to (a) external dose from I -MCi per cM3 of water, per cm3 of air, and per cmZ of ground surface; and (b) internal dose commitment from a I -MCi 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 fallout 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 (yCi) of each radionuclide and the fraction vented to the atmosphere. When indicated, the fraction not vented initially may be considered 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 radionuclides derived from a Radionuclide Dose Equivalent Index by the incorporation of information on initial distribution in time and space. A PRR considers fallout predictions, 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 (MCi/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.


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 magnitude of each parameter have on the compartments of interest. A pathway diagram of coupled compartments with designated parameters can be drawn when good bioenvironmental 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 estimating radiation dose will provide the final answer as to feasibility of the canal construction project. They were formulated only for a preliminary assessment of radiological safety-feasibility and are subject to future revisions and refinements.


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 interoceanic canal with nuclear explosives: Phase I. Oak Ridge National Laboratory. ORNL -410 1.

International Commission on Radiological Protection. 1959. Report of Committee II on permissible dose for internal radiation. ICRP Publ. Z, 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).




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.


Identification of those radionuclides which may contribute the most significant
dose equivalents""* to man is one of the primary objectives of a radiological- safety feasibility study. Dose models which facilitate the fulfillment of that objective are available, and a stepwise application of those models has been outlined in Part I of this twopart 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 classified 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 mod-e of exposure. The modes of exposure considered. were: submersion in contaminated air, submersion in contaminated water, exposure to a contaminated surface, and. ingestion and inhalation 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 (ingestfinnd,- inhalation) they were based on total dose delivered. to the critical organ.

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.


the potentially critical radionuclides do not exist in the environment in sufficient, quantities 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 distribution of radionuclides in the various environmental media at the site of sampling provided 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. Th e 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 summedpercentage 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 likely to be of principal importance in the feasibility study, changes and. improvements in the identification of critical radionuclides or elements can be expected as more information becomes available. It is important to note that the dose calculations, 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 devicedetonation 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 populations. 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 manljO, parameters in the dose models. "Standard mantl 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,


Immediate Hazard(a) Long Term Hazard~b

Inge stion Inhalation Ingestion
Soluble Insoluble Soluble Insoluble Soluble Insolubl

Lead Lead. Lead Lead Hydrogen Hydroge

Manganese Mangane se Mangane se Manganese Strontium Tungste

Iodine Tungsten Plutonium Hydrogen Tungsten Ruthenu
T ung sten Sodium Iodine Tungsten Ruthenium Cerium

Sodium Hydrogen T ung sten Sodium Plutonium Mangans

Zirconium Iodine Sodium Iodine Cerium Plutoniu

Yttrium Strontium Yttrium Strontium Manganese Zirconu

Strontium Yttrium Strontium Yttrium Calcium Yttrium

Ruthenium Ruthenium Zirconium Zirconium Lead Cesium

Cerium Zirconium Ruthenium Ruthenium Iron Beryllu

(a), Based on radionuclide production and venting estimates with no radioactive decay prior to intake.
(b) Based on radionuclide production and venting estimates with 1 year of radioactive decay prior to intake.



Immediate Hazard.(a) Long-Term Hazard(b)
Submersion in Contaminated. Submersion in Contaminated. Exposure to a Contamiae
Air or Water Air or Water Ground. Surface

Lead Hydrogen Ruthenium - Rhodiumrc

Sodium Tungsten Tungsten

Hydrogen Ruthenium - Rhodium Manganese

Tungsten Manganese Strontium Yttrium

Mangane se Zirconium - Niobium Yttrium

Iodine - Xenon Beryllium Zirconium - Niobium

Barium- Lanthanum Cesium - Barium Cesium - Barium

Krypton- Rubidium Strontium - Yttrium Beryllium

Ruthenium - Rhodium Yttrium Promethium

Tellurium - Iodine Cerium Krypton - Rubidium

(a) Based on radionuclide production and venting estimates, total dose equivalent received in 13 weeks or less.
(b) Based on radionuclide production and venting estimates, dose-equivalent rate after 1 year of radioactive decay.
(c) This notation indicates that the dose contributions from the daughter radionuclides have been considered. In this case, for example, ds
contributions from rhodium isotopes present as a result of radioactive decay of ruthenium were added to the dose estimates for the rutheiu isotopes; whereas, dose estimates for the rhodium isotopes to be produced directly during the detonations were treated as a separate eity



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. Tritiated 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 (Ii), effective absorbed energy (Ein), fractional absorption of the radionuclide in the organ (fin), effective elimination constant of the radionuclide in the organ(Xin = 0.693) and the mass of the organ (mn). In the case of HTO, fin is Te
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 estimates 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 following expression:

1n2 ni(n 2
Tb =Xb -it'/M (i

whe re

Xb = biological elimination constant (days-1) 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 poo1.

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 (FAG, 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 poo1



45 40 35



15 10



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



5 10 15 20

40 60

AG E (y r)





~0 1J 0L






(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 (FAQ, 1957) and, the concentration of oxygen in exhaled air (Altman et al. , 1958), with the assumption that ambient air is 20. 9 percent 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 containing 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 plotted are the infinite dose equivalents (reins) 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 thel body-water poo1. 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 commitments 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 1311 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 13 11 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 13 11 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

radionuclide intake.





(0 18 -4
E "

0 0

z 0





0 5 40 15 20 40 60
AGE (yr)




4.0 3.8 3.6

3.4 3.2

E 3.0

(f) 0
2.8 2.6

2.4 2.2 2.0 FIGURE 5-4. A


0 5 10 45 20 40 60
AGE (yr)







3 6 9 42 15 48 21

AGE (yr)




A-- 0

E '0

o 0'






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


Age, if, in , Tein,
yr 1 MeV days g

0-2 0. 5 0.2 0.21 4.0 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 6.0o 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, 6in, and Te) is no greater than a factor of two for any age. These results could be anticipated upon inspection of the data in Table 5-3. It must be admitted that the age dependence of Ii, E6in, and Te are not accurately known for a Caucasian population and even less is known concerning them for the populations of primary concern 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 (inn) 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 agedependent variations in in, Te, and fin. Figure 5-5 shows that the dose to the thyroid. of an infant, as a result of 13 11 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 variations 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 evaluate the age-dependent parameters in the dose estimation models and. the importance of considering them collectively as programmed. in the INREM code.



Organ or Tissue NCRP(a) FRC(b) ICRP IAEA

Gonads, Red Bone Marrow 0.5 0. 5(c) 0.5 0.5

Total Body 0.5 0.5(c) 0.5 0.5

Lenses of the Eyes 0.5 1. 5(d) 05

Other Single Organs 1.5 1.5 1.5

Skin, Bone, Thyroid 3 1.5(e) 3(f) 3

Hands, Forearms, Feet, Ankles 7.5 7.5 7.5

(a) These levels are based on NCRP's simple recommendation that the permissible dose to members of the population at large be reduced to not
more than 1/10 of the occupational values.
(b) The FRC does not recommend Radiation Protection Guides (RPG) for individual organ doses to the population other than gonads, whole body,
and thyroids.
(c) The FRC specifies that RPG for gonads shall be 5 reins in 30 years for average population groups on the assumption that the majority of
individuals do not vary from the average by a factor greater than 3; thus, the permissible annual dose to gonads and whole body for average
population groups would be 0. 17 rem.
(d) The ICRP recommends an n-factor of 3 for radiation to the lens of the eye of high LET. Thus the recommended absorbed dose is 1. 5 rad/yr
for x, y, or radiation and 0. 05 rad/yr for radiation of high LET, e. g., neutrons, for which QF = 10.
(e) The FRC recommends RPG's for the thyroid of 1. 5 rems/yr for individual and 0. 5 rem/yr to be applied to the average of suitable samples of
an exposed group in the population.
(f) The ICRP recommends less than 1. 5 rems/yr to the thyroid of children up to 16 years of age.


society from the conduct of peaceful nuclear operations. There appear to be no important 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 implies 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 permissible 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 radionuclides of greatest potential importance. Unfortunately, the application of the doseestimation 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 jud.ged. by balancing the benefits and risks.


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 Fluid.s. 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 Radiation Protection Standard.s. Report No. 1. U. S. Government Printing Office, Washington, D. C.

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., 5. M. Hollander, andlI. Perlman. 1967. Table oflIsotopes. 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.



Reina Torres de Araiioz'""


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. Demographic and dietary data are discussed in relation to the environment of each cultural group.


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 kin2).

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.







Isad So Js



-" (87,321 HECTARES--PUBLIC LAW 18, NOVEMBER8, 1934)






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

GroupE 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, precoded que stionna ires
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.


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 groupDs have the highest rate of fecundity between the ages of 20 and 25.


Adult Male Total Weekly Intake of Food

Group D
Source Gr oup A Group B Group C Group D1 Group D2 Group D3. ru'4 ru

Agriculturaliproducts 81.9 86.4 83.7 76.3 83.9 73.97208.

Fishing (sea fish) 11.3 - -- 10.7 -- 11.3172Fishing (river fish) -- 6.3 7.6 -- 6.9 -- - .

Hunting 1.7 7.2 5.9 -- 1.0 3.34.12

Cattle and poultry products -- -- 1.6 1.7 5.4 6.62477

Imported products 4.9 - 0.9 11.0 2. 7 4.94.10

Group A = Cuna Indians of San Bias Islands Group B = Cuna Indians of Bayano and Chucunaque Rivers Group C = Choco Indians Group D= Negro Populations Group Dl Negroes (Estuarine Ecosystem)
Group D2 = Negroes (Fluvial Ecosystem) Group D3 = Negroes (Coast Ecosystem) Group D4 = Negroes (Island Ecosystem) Group E = Colonists.


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).


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 subsistence activities and the species utilized by the different cultural groups depends to a significant extent on the kinds of bioenvironments available at different locations.


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-Z) of the total diet.

The Cuna Indians of the San Blas 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 agriculture 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-raisinga which takes them inland and away from the river banks. The cleared


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.


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.

Lives tock-rais ing -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 areasI are cleared and converted to artificial pasture.

Gathe ring

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,


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.


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 common 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


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, agricultural 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, especially 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 everything 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 (Pecani 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


The Negro Population (Group D)

The Negro population of the study area, approximately 19, 9Z5, 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). Demo graphically, 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 population 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 3Z percent live along the principal rivers of the region. The insular subgroup of the Negro population, about lZ 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-Z) 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 DZ) 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 consumption 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. Z 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 relatively 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-


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 characteristic 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 popularized 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 consumption 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.


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

6-11 and 6-12


Contraloria General de la Republica, Lugares Poblados. Sexto Censo de Poblacion y Vivienda, Direcclon de Estadistica y Censo, Panama, 1962. Contraloria General de laRepublica. Poblacion Indigena. Sexto Censo de Poblacion y Vivienda, Direccion de Estadistica y Censo, Panama, 1964.


Felix Webster McBryde**
Alfredo Costales Samaniego***


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,


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 population 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 Ungui, 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 "turban", 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)





15 10 15 110 115 120 125 1 30


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, expecially 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 Serraniai del Darie~n (Sautata", Unguia, and Santa
MIa. Nueva, or Cuti); the Upper Truandc and Salaquf', in the foothills of the Cerros de Quia; and the Pacific Coastal area (Curiche and Cored6).

Atlantic Lake Region. Though the region has elevations from sea level to more



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 Department 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 considering 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 movements, in which job hunters offer their services in such va ried 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



Land Resources

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" (Cut ) 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, name, sesame, and sugar cane, are less important, but have their place in the local diet and market, accounting for 7 percent or 1, 428, ZZ 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

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


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 problems 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 introduced,

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 tis associated with this nomadic agriculture. Terracing is used on slopes, especially for grazing,


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.

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 "prgul and the wider "1canoa"f, to permit navigation of the rivers, To build them, first-class woods, such as ceiba, chibuga, caracoli (espav6"), cedro, and cativo, are chosen for durability. The specialized trade of the boat-builders permits fishing in the river netw ork of the Atrato, the Truand6", 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,


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 inventory of menus for 7 consecutive days. Following are some general considerations:

The nutritional study involved 60 families in two Indian communities (Cuna and



Only in Salaqui were long-term data on individuals collected because the constant mobility of the Choco families along the Salaqui and Tamboral Rivers rend I ered 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 deriv ' ed 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 compound, 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


(Based on preliminary analysis of data collected by field teams of IEAG)-(a)

Localities: Cuti Unguia Arquia Sautata Salaqui Truand Curichi Cored
Ethnic Groups: Mixed Mixed(b) Cuna Mixed(c) Choco Negro Negro Negr

Major Kinds of Foods:

Agricultural Products 64.2(d) 73.1 89.0 67.1 86.9 61.9 63.0 70.4

Banana and plantain 12.4 31.8 63.7 23.8 84.5 44.4 26.2 41.6
Rice 26.5 24.0 13.0 17.0 -- 15.5 22.8 13.2
Corn 4.0 1.9 3.3 1.9 2.4 -.
Other 21.3 15.4 9.0 24.4 -- 2.0 14.0 15.6
Domestic Animals 33.5 17.4 0.5 23.1 0.5 17.8 9.4 8.9

Meat and eggs 16.3 6.3 0.5 10.4 -- 12.2 9.4 3.0
Milk and milk products 17.2 1i.I -- 12.7 0.5 5.6 -- 5.9

Game (birds and mammals) .-- 7.2 1.6 0.6 .
Fish and shellfish -- 4. 1 2.2 -- 11.0 11.0 192(e) i.o(

Imported and miscellaneous 2.3 5.4 1.1 9.8 -- 8.7 8.4 9.7

Basis for Estimation:

Number of people studied 38 94 35 68 38 110 52 38

Duration (days) of study 7 7 8 5 1 7 5 7

(a) Instituto Ecuatoriano de Antropologi y Geografia (Ecuadorian Institute of Anthropology and Geography).
(b) The majority are Caucasians and the minority are Negroes.
(c) The majority are Negroes and the minority are Caucasians.
(d) Underlined numbers are total percentages for major categories.
(e) Most of the fish and shellfish consumed by these two groups are of marine origin while most of the fish and shellfish consumed by the other groups is of fluvial origin.



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: 11nourishing", 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, 9. , 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 . 00
papaya, guama, or boro3o, 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,


Three fundamental aspects of food consumption were t created 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 capita 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,

7-11 and 7-12

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, Examples 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 percentage 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



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


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.


In agriculture -food chain relationships, previous studies have been concerned
primarily with 90Sr, 137CS , and 1311. 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 compartments 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).



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 i n 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, manganese 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 plantains. 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-


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 restricted 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 consideration. 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.


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 necessary to have a soil survey and to select principal soil types for detailed study. Soil samples were collected with all crop samples in ord er to correlate possible crop compositional variations with soil-extract analysis.

The p-rincipal agronomic"soils are on recent alluvial materials. The most comMon 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 w1th 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-


(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 determined in the region of 50-250 C [LR] and 500-700 C [MR]. Georgiakaolin 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 interlayering 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.


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 Z7 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 i11 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 stIMH
Uala 60 755 30 7.9 53 34 stAIMH

(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; 86R b-137Cs; 45Ca-89Sr (Paper 12).


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.


(1) Covich, A. P. and Nickerson, N. H. 1966. Studies of cultivated plants in Choco
dwelling clearings, Darien, Panama. Econ. Bot. 20:Z85-301.

(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 11lZ (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.



Location pH(a) p(b) K(c) Ca Sr Mg Fe Mn Cu Zn Al
Rio Iglesias 6.3 10.5 345.0 4000.0 187.2 350.0 0.8 28.0 0.8 1.9 5.0

Santa Fe 5.Z 9.1 650.0 2420.0 214.Z 700.0 1.6 14.5 0.6 2.1 10.0
Yaviza 6. 1 6.3 102.5 4400.0 235.2 600.0 0.8 4.9 1.2 3.2 8.0
Rio Balsas 6.3 13.4 300.0 5100.0 150.0 800.0 0.8 9.5 1.4 1.8 12.0

Mulatupu 6.3 0.4 52.5 3610.0 127.2 800.0 0.4 1.0 1.0 1.9 12.0
Sasardi 4.9 0.4 57.5 305.0 30.0 50.0 Z.0 NA 1.2 2.4 11.2

Sambu Valley 6.5 10.6 190.0 5000.0 150.6 960.0 NA 0.7 1.0 1.2 NA
Morti Abajo 6.5 16.5 540.0 6300.0 80.0 1270.0 2.2 5.0 NA 5.1 NA

Santa Fe 6.7 14.0 850.0 4700.0 72.3 1620.0 0.6 22.4 0.5 3.3 NA
Patino 6.9 2.8 430.0 3850.0 35.0 459.0 0.5 32.5 0.2 0.7 NA
Trocha 4.6 0.7 80.0 7500.0 251.4 1330.0 1.6 0.3 0.4 2.5 3.0

Uala 5.7 1.8 875.0 3750.0 28.8 605.0 1.5 4.5 1.2 3.9 2.7

NA - not analyzed.
(a) 2:1 water:soil suspension.
(b) Ammonium Molybdate - Stannous Chloride method (Fisher Electrophotometer).
(c) Beckman D. U. Flame Photometric Analysis.
(a, b, c) - determined in Tropical Soils Lab. All other determinations by Atomic Absorption (Perkin Elmer No. 303) in Central Analytical Lab.



Samuel C. Snedaker and John F. Gamble%


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 compositional- 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 vegetation 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 compositional 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 different ecological zones in Ghana.

Datan colIlected f, rom ";a a series 11 of -Tfallows o--f knOwne N Tv%-Th Lake_ Izabl reI o

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

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-e ' ecology s ' tudy, 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 secondgrowth 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-Z 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 196Z. 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 s ecies. Aside from the error normally associated with analytical procedures, 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


Age, Soil, Wt., Percent, dry wt. basis PPM
Species yrs pH percent N P K Ca Mg Sr Cu Fe Mn Zn Al Source

Abutilon sp.

Bursera simaruba
(L.) Sarg. Cochlospermum vitifolium Spreng.

Eugenia sp. Genipa caruto HBK Heliconia latispatha Benth.

Lantana camara L. Paspalum fasciculatum Willd. ex Flugge

Piper aeruginosibaccum

Piper auritum HBK Scheelea lundellii Bartlett












7.0 26.5
7.1 20.9

7.0 38.4

NR NR NR 7.0 6.9 6.9 6.9 NR NR NR NR NR 7.1 NR NR NR 7.0

6.9 6.9 NR NR

24.9 NR NR NR 43.0 15.0 16.8 21.7 NR NR NR 22.3 19.7 32.5

NR NR NR 16.5

11.5 46.2 NR NR

1.80 0.15 2.90 0.23 1.64 0.11

2.42 0.23 1.65 0.15 2.67 0.23 1.86 0.17 1.78 0.12 2.46 0.18 1.65 0.19 1.91 0.16 3.14 0.26 3.32 0.24 3.37 0.22 1.20 0.06 1.15 0.07 1.85 0.13 0.89 0.25 0.96 0.29 0.88 0.23 2.53 0.20

3.83 0.41 1.47 0.08 1.62 0.13 1.63 0.13


1.38 0.42 0.35 21.3 7.8 35
1.64 0.49 1.18 22.5 15.8 68

1.03 0.88 0.42 55.0 4.0 50

1.31 1.88 1.80 NR 0.70

1.64 2.90 2.13 1.61 1.61 1.38 1.61 2.03 0.93 2.89 2.52 2.00 2.46

4.90 0.35 0.62 0.56

0.40 0.44 0.33 0.54 0.65

0.29 0.28 0.49 0.52 0.60 0.68 0.30
0.25 0.71 0.13 0.16 0.12 0.69


0.23 0.17 0.19

0.70 0.75 0.71
0.78 1.28

0.38 0.81 0.78 0.71
0.80 0.55 0.89 0.88 0.55 0.32 0.34 0.31 1.19

1.34 0.57 0.31 0.36

27.5 32.0 41.0 45.0 40.0 5.0 15.0 21.3 19.8 23.3 39.0 NA NA 56.3 7.5
7.5 7.5


53.8 6.3 8.8 8.8

8.5 10.8 10.8 10.5 4.8 22.0 19.3 12.3 10.5 17.8
13.2 NA NA 10.0 20.5 20. 5 24.0 13.0


16.3 17.2 15.5

6 32.0 20 41.3 24 10.0

59 16 18.3
475 47 26.2
214 38 27.5
289 35 35.0

48 11 21.0

65 120 44.0 78 108 22.3 38 13 19.0
126 102 23.8 206 111 30.0 134 124 26.2 NA NA NA

53 21 44.5

186 38 37.5
218 36 40.0
245 35 35.0

108 46 56.3


70 157

20 44.8 9 20.0 25 32.5 25 32.5

25 25 10

15 NA NA NA 35 30 25 25 NA NA NA NA NA 15 NA NA NA 35


25 NA NA












10.0 41.5 135 24 40.0 NA (1)


NR Ni R I 6 0.13

0.51 0.20 0.36

TABLE 9-1. (Continued)

Smilax sp.

Tabernaemontana chrysantha Blake Tecoma stans (L. ) Juss. Thevetia nitida (HBK) A. DC. Trema micrantha
(L.) Blume

Waltheria americana L. Leguminosae (E-190) Allophyllus cominia
(L.) Sw.

Heliconia sp. (Chiman)

Carludovica palmata R. & P. (Ailigandi)

Veg. Age, yrs NR NR








Soil, pH NR NR 7.0

6.9 7.0

6.9 NR NR NR NR NR 7.1 6.9.


6.3 5.1 6.0 5.1

Dry Wt., percent 29.5
36.3 23.6

Percent, dry wt. basis
N P K Ca Mg
1.18 0.06 1.08 0.44 1.02 1.15 0.08 1.30 0.31 0.88 2.86 0.26 3.58 1.47 1.11

39.9 1.55 0.13 1.18 0.56 0.37 16.4 1.79 0.18 3.86 0.97 1.44

27.4 NR NR NR 33.5 32.1 29.9 26.7 31.4



2.43 0.17 0.78 0.96 1.23 1.62 0.11 0.60 .1.64 0.98 I.70 0.10 0.68 1.48 0.94 1.73 0.13 0.69 1.35 1.08 0.91 0.03 0.74 0.44 0.74 1.40 0.04 0.91 0.63 1.10 1.79 0.11 1.48 0.68 0.57 2.55 0.19 1.57 0.95 0.34

1.86 0.18 1.11 1.03 0.79


2.08 0.17 1.49 0.62 0.37 1.90 0.17 1.03 0.49 0.31 2.44 0.26 4.90 0.51 0.26

1.52 0.13 0.50 1.51 0.47

Sr Cu Fe Mn Zn Al

41.3 17.0 188 33 38.5 25

18.8 12.3 38 14 38.0 5

1090.0 9.0 50 49 26.8 25

97.5 169.0 156.0 123.0 NA NA 47.5 110.0

125. 0

21.5 6.3 7.5 55.5

48.8 143 13 32.5 35 31.2 169 24 22.5 NA 29.5 157 22 22.5 NA 35.0 351 23 25.0 NA NA NA NA NA NA

13.3 59 26 36.5 35

11.5 45 31 20.8 20

5.5 55 16 39.0 20

10.5 100 194 0.9 NA 3.0 79 205 0.7 NA 25.0 131 117 1.2 NA

45.0 300 58 1.7 NA












NA - not analyzed. NR - not recorded.

Sources: (1) J. Ewel
(3) H. Popenoe

(2) J. Gamble
(4) S. Snedaker


pH pH O. M. 0 No PPM
H2O KCL percent percent Na P K Mg Ca Sr Cu Fe Mn Zn A


3 Year Old Fallow:
0-5 5-20
20-40 5 Year Old Fallow:
0-5 5-20

8 Year Old Fallow:
0-5 5-20

Chiman 0-10

Ailigandi 0-15

Manene' 0-15

6.81 6.22 11.33 7.01 6.25 3.79 7.24 6.28 1.35

6.80 6.27 12.63 7.15 6.52 3.17 7.35 6.56 1.24

6.72 6.22 13.04 7.01 6.28 3.09 7.37 6.38 1.88

6.3 4.9
6.1 4.2

5.1 5.1
5.7 4.2

6.0 5.6

104 12.47 511 4580 2550
73 1.04 218 3440 1000
57 0.37 163 3260 560

102 7.74 490 3690 2310
70 2.49 182 2000 860
69 1.65 153 1680 450

103 62 53

0.30 0.10 0.25 0.05


5.84 535 5760 2280
1.20 185 3600 820
0.82 146 3480 670


0.09 368 195 5725 27.4 NA 0.60 9.78 0.74 0.0
0.01 90 195 5200 29.5 NA 0.60 2.95 1.37 0.0

0.02 332 456 1600 81.4 0.40 0.32 0.72 0.72 2.0
0.02 206 296 1080 52.6 0.48 0.64 4.00 0.76 2.0

0.05 318 428 2720 63.4 0.40 0.16 0.44 0.76 5.0

pH H20 - 2:1 H20 to soil suspension
pH 7. 0 N NH4OAc extract
P - ammonium fluoride extract

(a) S. Snedaker
(b) J. Gamble

Depth, cm


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.


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

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

(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,


W. Ne ill Thomas son'W. Emmett Bolch*'"
J. F. Gamble"'*


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.


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 specificactivity relationships or uptake factors relative to the stable-isotope compositional analyses. It was not possible to introduce radiotracers into the uptake experiment conducted 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 Introduction Station were utilized to obtain some information on uptake of critical ra-dionuclides in tropical food plants. The radionuclides used in this study were 185W, 855n, 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




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 shee ting 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, 855r, 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 ptXi/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 breakthroughs, 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 tni-component shield, housed in a large, low-level equations.

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

Stable concentrations of calcium, iron, manganese, cesium, potassium, magnesium, 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 r(Sutes,


0.5 1.0 1.5

0.5 1.0 1.5


0 O.

0 O.




0.1 1 1 1 ! 1 I I I ! .1 1
0 10 20
TIME, days



FIGURE 10-3.


FIGURE 10-4.









TIME, days


TIME, days

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,


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 radiotracers 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 selectiveprecipitation technique developed in this study, which use-s a sodium tungstate carrier and cinchonine, a tungsten complexing agent. Ninety-three percent separation of prepared 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 concentration. 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



750 cpm for Tree 1, Tree 2, and Tree 3, respectively. While about 16 percent more activity was applied to Tree I 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 radionuclides.


The study has demonstrated the feasibility of conducting environmental tracer
experiments. For a given amount of effort, one has the alternatives of either (1) greenhouse experiments with a highly artificial environment, but with more statistical control, or (2) field experiments under natural conditions, but with minimal statistical design. The investigators feel the latter choice has considerable merit. Further conclusions 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,



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


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.


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). Uncertain 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 proposed sea-level-canal route in Panama. The ranches were located at Yaviza, Santa Fe, El Real, and. Pati no. Animal tissue samples were obtained. from El Real, Santa Fe, and from animals that had. been raised near David. in Western Panama.


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 Patino. 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 Patino 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 1 1. 0. Soil pH was abov e 5. 5 'inmost cases and ammonium acetate

TABLE 11-1.


(0-15 cm) FROM

O rganic Total Total. Extrumacbe, ppm
Soil Matter, N, xratbe
Texture pH percent ppm C/N ppm Ca Mg P KS


Silty clay 6.1 5.35 3160 9.8 772 6710 1513 1.1 398

Santa Fe

Clay 6.0 5.27 3550 8.6 833 7880 1144 1.7 665

El Real

Silty clay 6.1 7.67 4490 9.9 959 8920 944 2.5 357

P a t i~o

Silty clay 6.4 4.67 2625 10.4 375 3570 1153 0. 2 103

Sandy loam 6.0 2.92 1610 10.6 750 2340 815 0.4 5715

(a) Data were calculated on the basis of air-dry soil.


high - 194 to 754 ppm - with the exception of the Patifib soils (which were also lower in phosphorus'); these two contained only 131 and 158 ppm potassium.


Grass forages and an associated legume were collected from each ranch in association 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 deficiency; 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 season. 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 efficient 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 contained 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 associated legume growing on poorly drained areas at Yaviza and El Real,

An opportunity was provided at Patin'o 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 requirements. 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


TABLE 11-2.


Percent PPM
Species N P K Ca Mg Sr Zn Mn Fe

Jaraguagras s
Guineagras s Paragrass

Jaraguagras s Guineagras s

Jaraguagras s Guineagras s Paragrass
Pangolagras s Legume

Jaraguagras s Paragrass
Pangolagras s

1.76 1.52 1.45 3.23

1.72 1.29 2.61

0.91 1.44 0.99 1.58 3.38

1.30 1.43 1.97

0.31 0.39 0.25 0.27

0.28 0.36

0.18 0.28 0.19 0.27 0.36

0.13 0.32 0.36

2. 07 4.88 2.21 2.34

1. 94 3.31 1.69

1.41 4.56 2.21
3.06 2.50

1.57 2.29 2.27

0.44 0. 23 1.17

Santa Fe
0.29 0.30 1.37

El Real

0.43 0.35 0.29 0.35 1.43


0.42 0.23 0.33

0. 17 0.32 0. 16 0.26


17 19

0. 09
0. 19 0.10 0. 13 0.33

0. 16 0.21 0. 18

36 31 16 83

39 19 114

26 18
14 23

14 29

36 38 60 30

36 48 28

25 41 41
63 45

38 53

38 50
213 50

39 64

53 28 45
188 60

180 82

313 226 2550 394

150 91

119 300 156 575

175 138 141

(a) Data were calculated on the basis of oven-dry forage (70 C).



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 crossbred steers and one bull of similar breeding ranging in age from 2 to 3 years were sampled from the Patifio 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 tissue 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 drymatter 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 Patiiio area. The iron concentration of the spleens from the El Real cattle was higher than that of Patiiio 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 Patiino and David, respectively. There are large differences in the bone strontium concentration with a ratio of 1:3:10 among El Real, Patiiio, and David. El Real soils are similar. The soils from the Eastern Panama sites are different, but their strontium concentrations are not extremely 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 Patiiio cattle.

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.


Tissue P K Na Ca Mg Fe Cu Zn M

El Real

Liver 1.2 1.1 0.44 13.3 670 159.1 35.8 172Z63 .
Kidney 1.2 1.1 0.91 103 680 269 38 102842
Heart 1.0 1.3 0.43 146 1000 37 81 941.29
Spleen 1.5 1. 8 0.56 22.8 660 918.4 14.09 1005.31
Muscle 0.8 1.5 0.24 70.3 980 96 22.6 160.25 .
Bone 17.6 0.03 1. 1 3 8. 7% 5480 35 4.0 131 249

Liver 1.3 1. 1 0.34 36 755 242 309.5 208.5 1 .
Kidney 1.2 1. 0 0.83 475 785 234 110 124 1. .
Heart 1. 0 1.3 0.40 75 1040 233.5 9. 0 1167.01
Spleen 1.3 1.7 0.39 21.8 745 624 67 160 1. .
Mus cle 0.7 1.3 0.30 225 860 127 80.3 380. 0 9.04
Bone 17.8 0.04 1. 1 39.3% 6570 10 3. 1 1061.29

Liver 1.2 1.2 0.31 15 600 533.5 816.5 162.5 9528
Kidney 1.2z 1.2 0.91 350 940 430 42.8 113.5 8.15
Heart 1. 0 1.5 0.47 130 1270 267.5 44.8 127.5 4.14
Spleen 1.3 1.7 0.41 75 855 810.5 12.7 1405.07
Mus cle 0.8 1.5 0.35 194 960 100 31. 1 4301.09
Bone 18. 1 0.03 1. 1 40.9% 6270 13.5 3.2 15511 87

(a) Data expressed on a dry -matter basis for soft tissue; ahwih o oe


ash weight for bone.