July 22, 1955
COOPERATIVE EXTENSION WORK IN
AGRICULTURE AND HOME ECONOMICS
(Acts of May 8 and June 30, 1914)
AGRICULTURAL EXTENSION SERVICE, UNIVERSITY OF FLORIDA
FLORIDA STATE UNIVERSITY
AND UNITED STATES DEPARTMENT OF AGRICULTURE
H. G. CLAYTON, DIRECTOR
Some Questions and Answers on
Vegetable Pesticide Tolerances
(Prepared in cooperation with the Florida Agricultural Experiment
Stations, Florida Fruit and Vegetable Association and Florida Agricultural
The U. S. Food and Drug Administration has recently estab-
lished tolerances on amounts of certain pesticide chemicals that
are permitted to remain in or on fruits, vegetables and other raw
agricultural commodities, and has also listed other pesticide
chemicals exempt from requirements of a tolerance.
Certain tolerances set by Food and Drug Administration be-
came effective on July 22, 1955. On certain other pesticides
the effective date was extended to October 31, 1955. Additional
tolerances, or changes in tolerances, may be set from time to
time. Agricultural commodities in interstate commerce not in
compliance with these regulations are illegal and subject to
The administration of these tolerances is the responsibility of
the Food and Drug Administration under the U. S. Secretary
of Health, Education and Welfare, operating under the author-
ity of the Food, Drug and Cosmetic Act. The Miller Bill passed
at the last session of the Congress as an amendment to this
act set up machinery for handling and expediting the setting of
tolerances and related matters.
This leaflet is an attempt to single out some of the more
pertinent information available on the subject which at this
time seems to be of particular general interest to Florida agri-
It does not contain the complete texts of the various regula-
tions which established the tolerances and exemptions; these
are in the Federal Register and the Code of Federal Regulations
under Title 21, Chapter 1, Parts 3 and 120.
No doubt other information is and will become available, de-
pending on the specific conditions. All persons concerned are
urged to use every means to avail themselves of the latest in-
Why Have Tolerances Been Established?
Some pesticides are more or less toxic to humans; others are
It is significant to note that tolerances have been established
through cooperative efforts of farm and grower groups, manu-
facturers, federal agencies, state universities and others.
Tolerances, and accompanying judicious interpretation and
enforcement, should assure the consumer that, in the light of
the best available scientific information, no public health hazard
due to pesticides is evident.
What Is a Pesticide Chemical?
It has a legal definition under the Federal Insecticide, Fungi-
cide and Rodenticide Act, including the commonly accepted terms
indicated in the name. However, it would be well to note that
several materials known generally as weedicides, fruit-set com-
pounds, seed treatment materials, and fumigants are given
What Is a Tolerance?
The maximum amount of pesticide residue that may lawfully
remain in or on food without hazard to man.
Thus, a tolerance of 1 ppm (parts per million) for "X" chemi-
cal means that no more than 1 part by weight of "X" chemical
may remain in or on 1 million parts of any food; expressing
it in terms of a 1-pound sample, a 1 ppm tolerance would be
0.000001 of a pound.
A tolerance becomes official when so published in the Federal
How Will Tolerances Affect Florida Growers,
Shippers, Suppliers and Others?
This depends on any number of considerations, including such
items as interpretation and enforcement of the regulations, field
and packinghouse practices, and others.
Concerted efforts are underway to make available the latest
research information for the coming season.
Growers and shippers have grave responsibilities under this
law. These may be stated briefly as (1) not to use pesticides
which will result in food crops residues for which no tolerance
or exemptions have been established, and (2) to use pesticides
for which tolerances have been established in such a way that
the residues are within the established tolerances.
What About the Chart Inside This Leaflet?
It is an attempt to summarize for Florida vegetables most
pesticide tolerances effective July 22, 1955, extensions to date
granted to October 31, 1955, and suggested minimum days be-
tween last application and harvest within limits of Florida Agri-
cultural Experiment Station residue research to date. It is
recognized that other residue data exist. However, these have
not been completely evaluated or made currently available as a
part of this publication.
It is anticipated that numerous changes may rapidly come
about, but that such a summary at this time is needed to visualize
the current general situation. Space has been allotted for in-
sertion of new materials and crops, or for addition of omissions
in line with specific interests and needs.
What Pesticide Chemicals Are Exempted from the
Requirement of a Tolerance?
When applied to growing crops in accordance with good agri-
cultural practice, it appears that the following involve no hazard
to the public health:
Bordeaux mixture, copper acetate, basic copper carbonate
(malachite), copper-lime mixtures, copper oxychloride, copper
silicate, copper sulfate basic, copper-zinc chromate, cuprous
oxide, petroleum oils, pyrethrum and pyrethrins, rotenone or
derris or cube, ryania, sabadilla.
A SUMMARY OF FLORIDA V
*--tolerances effective July 22, 1955
**-effective date extended to October 31, 1955
VEGETABLES l c S 2
) p 0 P P p g p0 4-) O0) 0p -3 40P
Beans ** *-5 ** | 1 **-3 I *-3
English pea ** ** ** ** *
Southern pea ** *-5 ** *-3
Beet ** | ** ** ** *
Carrot ** | |** | ** *
Corn ** I *-5 ** | ** *-5
Broccoli ** *1 *-14 ** ** *-10
Cabbage ** ** | *-14 ** ** **-7 | *-7 I
Cauliflower ** *-141 ** ** ** | *-7 |
Greens: |_______ II_____ ||
Collard (Kale) ** ** |* ** | *
Mustrad i** __| | ** |* | ** *
Turnip 1*i ** | * ** ** **-7 * *-141
(Spinach) ** | I ** | ** | *-141
Cucurbits: 1 || | | | _________
Cantaloupe3 ** ** ** ** *
Cucumber ** __ | **I |** *
Squash |** I* I ** I* ** *-3
Watermelon3 ** ** 1* **| ** *
Okra4 I-** * J ** | *| *-3
Onion F**| ** ** ** __ *
Potatoes: | | |
Irish | * ** | | | **__| __|
Sweet | | ** | ** | ** ** | _| |
Radish F ** ** | | *| *
Salad: |____ ___|_
Celery ** *-14 ** *-71 | *-7 |
Endive (Escarole)'" ** ___ | *-211 ** __*-141
Lettuce 1 ** *-21| ** | ** *-14
Solanaceous: F | I |
Eggplant I ** * ** ___|* ** *
Pepper| ** I* ** | ** *
Tomato ** *-14 *-3 ** ** ***| ** | *-3
Strawberry ** | * | ** | * ** * *-3
___________________ I I I !I I I ___ ____
1Chinese cabbage: does
not have tolerances listed as such; suggested intervals from last
application to harvest are: toxaphene-21, DDT--21, parathion-10 (days).
2Collard (Kale): applies to both crops: exception malathion extension-applies to kale only.
3 Cantaloupe and watermelon: double listing on lindane noted-no clarification to da'e.
LE PESTICIDE TOLERANCES
bers-suggested minimum days between last application and harvest, within
limits of Florida Agricultural Experiment Station residue research to date.
S I VEGETABLES
0o < wo |o
CS ld .-
1 *-141 | J ** ** | Beans
|| ** 1* English pea
*-5 ** Southern pea
| ** |* | | Beet
*_____ * _Carrot
| | | |Crucifers:
*-21[ | Broccoli
S*-21 | [* |* | Cauliflower
** ** | Collard (Kale)2
** | * Mustard
** | I | Turnip
** | ** | ** (Spinach)
|[ | Cucurbits:
S II** ** | Cantaloupe:'
|| ** I* ** ** [ Cucumber
II ** | ** | | I I Squash
Sr **I | Watermelon"
| i|| ] Okra'
I| | | ** I I| Onion
| | |Potatoes:
S| ** | ** | Irish
| I | |* |I* Radish
*-21 **** | ** |* Celery
SI II *Endive (Escarole)y
** I *** I 1 |
S- ** ** ** |
| | ** | | ** r
II I I
TI ^ I _____________________-_________i_____________
1 i I
4 Okra: DDT and toxaphene; apply up to flowering time only.
5 Endive (Escarole) : residue research escarole only; tolerances apply both crops.
6 Maneb and zineb: terms used in official releases to date; until further clarification, chemical
similarity to properly reacted nabam plus zinc sulfate or manganese sulfate should be noted.
The following synergists are also included: N-Octylbicyclo-
(2,2,1) -5-heptene-2,3-dicarboximide), piperonyl butoxide, piper-
onyl cyclonene, N-Propyl some.
These pesticides are not exempted from the requirement of a
tolerance when applied to a crop at the time of or after harvest.
What Is a "Zero" Tolerance?
Unless a specific tolerance or exemption from the requirement
of a tolerance has been established for a poisonous or deleterious
pesticide chemical, residues of the chemical should not remain
on a raw agricultural commodity which is in interstate com-
merce. Thus, each pesticide chemical has the equivalent of a
zero tolerance until some specific action is taken by regulation
to establish a higher tolerance or an exemption for its residues.
Residues of the following should not remain on fruits or vege-
tables as prepared for market:
DNOSBP (dinitro-O-sec. butylphenol)
HETP (hexaethyl tetraphosphate)
TEPP tetraethyll pyrophosphate)
Selenium and selenium compounds
Does a Tolerance Apply to a Specific Formulation or to
A Pesticide Chemical Irrespective of the Formulation?
The tolerance applies to the chemical and not to any specific
formulation. Thus, once a tolerance is set on "X" chemical that
tolerance applies to residues of "X" chemical, irrespective of the
type or brand name of the formulation which was used to treat
How Are New Tolerances Established?
To request a tolerance on new pesticides, or involving a crop
not now covered, the following is the procedure:
1. File a petition proposing the tolerance, together with sup-
porting scientific data to establish safe residue levels, with the
Secretary of Health, Education, and Welfare (Administrator
of the Food, Drug and Cosmetic Act).
2. File with the Secretary of Agriculture a copy of the petition
and a request to certify to the Secretary, HEW, that the pesti-
cide chemical is useful for its intended purpose and that the
requested tolerance reasonably reflects the amount of residue,
if any, likely to result when the pesticide is used as proposed.
3. Within 90 days after certification by the Secretary of
Agriculture the Secretary of HEW shall:
(a) Establish a tolerance for the pesticide chemical, or
(b) Exempt the pesticide chemical from the necessity
for a tolerance.
How About a Situation Where Two or More Pesticides of
the Same Class, e.g., Chlorinated Hydrocarbons, Are Used?
In general, where residues from two or more chemicals in the
same class are present, the tolerance for the total of such resi-
dues shall be the same as that for the chemical having the lowest
numerical tolerance in this class.
However, further calculations can be applied if by quantitative
determination each residue can be singled out, or where one or
more but not all of the residues are determinable. Briefly, a
situation may be as follows: (The total amount of residues
present may not exceed 100 % when the amount of each residue
is measured percentagewise against the tolerance for that pa-
Example No. 1 Example No. 2
Tolerance ppm Percent of ppm I Percent of
Present Tolerance Present I Tolerance
DDT 7 ppm .......... 1 14% 4 5 57%
BHC 5 ppm .......... 2 40% 3 60%
In the case of Example No. 1 the crop would be considered to
comply with the DDT and BHC tolerances. In case of Example
No. 2 the crop would be considered adulterated because it con-
tained over 100 percent of the amount of the residues permitted.
This same method of calculation is followed, even though there
are several residues of the same class, e.g., chlorinated hydro-
How About a Situation Where the Residues Are of
Different Classes, e.g., Chlorinated Hydrocarbons
and Organic Phosphates?
Then the presence of one has no effect on the tolerance for
Thus, where a tolerance of 7 ppm for DDT and a tolerance of
3 ppm for EPN has been established, up to 7 ppm of DDT and
3 ppm of EPN may be present.
How Can You Be Certain Your Produce Will Be
Safely Within Tolerances?
To date, there is no sure-fire, single answer.
Among the many factors that influence the amount of residue
and, therefore, become important in keeping safely within estab-
lished tolerance limits are such items as:
1. The interval between the last application and harvest time.
2. Climatic factors-rain, wind, sunshine, etc.
3. Washing or other packing procedures followed in the
packinghouse or in harvesting and packing equipment.
4. Method of sampling and making determinations by enforce-
5. Concentration of spray materials as actually applied to crop.
6. Rate of application.
7. Frequency of application.
8. Type of formulation or product used-dusts, wettable pow-
ders, emulsifiable concentrates, etc.
Based on information at hand, and recognizing that there
could easily be specific exceptions, there should be a minimum
of problems concerned with tolerances in Florida if good judg-
ment and sound agricultural practice are maintained.
It seems highly desirable that label statements, directions,
and precautions be given constant reference and that full use
be made of the latest information available through research
of the Florida Agricultural Experiment Stations and other de-
It is recognized that additional information will be forthcoming
and consideration is being given suitable methods for making