1967 EVALUATIONS OF SOME PESTICIDE RESIDUES IN FOOD
The content of this document is the result of the deliberations of the
Joint Meeting of the FAO Working Party of Experts and the WHO Expert
Committee on Pesticide Residues, which met in Rome, 4 - 11 December,
1967. (FAO/WHO, 1968)
FOOD AND AGRICULTURE ORGANIZATION OF THE UNITED NATIONS
WORLD HEALTH ORGANIZATION
This pesticide was evaluated by the 1966 Joint Meeting of the FAO
Working Party and WHO Expert Committee on Pesticide Residues (FAO/WHO,
1967). Since the previous publication additional information on the
identity of dieldrin and the results of additional experimental work
have become available. This new information and work is summarized and
discussed in the following monograph addendum.
Other relevant chemical properties Per cent
Technical dieldrin contains:
dimethanonaph thalenes (endrin) 3.5
hexachloroethane less than 0.1
carbonyl compounds (1) 2
acetic acid 0.2
other compounds (2) 3.7
(1) At least three carbonyl compounds are indicated by the infrared
spectra. The quantitative approximation was made on the
assumption that these compounds are ketones, aldehydes and acids
derived from HCCPD and HHDN.
(2) Primarily a complex mixture of compounds formed by polymerization
of HCCPD and BCH during the aldrin reaction.
EVALUATION FOR ACCEPTABLE DAILY INTAKES
Biochemical aspects 1
In the rabbit, the urine is the major route of excretion of dieldrin
and its metabolites, while in the rat, faecal excretion is more
important; the principal metabolite detected in rat faeces is a
mono-hydroxy substitution product (Hunter, 1966).
A ketone metabolite of dieldrin has been found in the urine of rats,
dogs and man. In contrast to the rabbit, transdihydroxy aldrin is not
present in significant amounts in rat urine following administration
of dieldrin (Hunter, 1966).
Dieldrin was found in the urine of five men and five women with no
occupational exposure to chlorinated hydrocarbon insecticides. In the
men, the mean concentration was 0.0008 ppm (range 0.0005-0.0014) and
in the women, 0.0013 (range 0.0011-0.0019). In five men with high
occupational exposure, the mean concentration was 0.0514 ppm (Cueto
and Biros, 1967).
The mean whole-blood concentration of dieldrin in ten men with no
history of occupational exposure to dieldrin was 0.0014 ppm, with 61
per cent carried in the serum. The mean concentration in erythrocytes
was 0.0005 ppm (Dale et al., 1966).
In 12 men with 3 to 12 years' high occupational exposure to dieldrin,
the overall mean whole blood concentration was 0.08 ppm, with mean
extremes of 0.036 to 0.118 ppm (Jager, 1967).
product of dieldrin Dieldrin
Animal Route LD50 LD50
(mg/kg body-weight) (mg/kg body-weight)
Mouse oral 6.8 77.3
Rat oral 9.6 46.8
Guinea-pig oral 2.3-3.9 18-30
Pigeon oral 75-100 250
Chicken oral 80 48
Pheasant oral 90 -
Dog, male oral 120-160 120
Dog, female oral 80-120 80-100
(Brown et al., 1967)
1 For further information see p. 109.
The overall mean concentrations of dieldrin in quail and pigeons of
both sexes succumbing to single doses or high subacute feeding levels
were : 17.4 ppm (95 per cent limits, 15.9-19) and 20 ppm (18.1-22) in
the brains, respectively; and 40 ppm (34.7-46.2) and 45.6 ppm
(37.5-55.5) in the livers (Robinson et al, 1967)
The results of studies of convulsion thresholds for strychnine and
Leptazol in mice dosed orally with 15-60 mg/kg of dieldrin suggested
that central, but not peripheral, nervous transmission is facilitated
in acute poisoning (Natoff, 1967).
Mouse. Groups of five males and five females were fed 1, 3 and 10
ppm of the photoisomerization product of dieldrin for one month. There
was no survival at 10 ppm and 2 animals died at 3 ppm. No apparent
abnormalities were seen at autopsy (Brown et al., 1967).
Rat. Groups of four males were fed 0 and 200 ppm of dieldrin for
4-14 days and 2000 ppm of phenobarbital for 4-28 days. Similarly
another group was fed the control diet for 4-28 days after 12 days'
pre-treatment at 200 ppm. Similar ultracellular responses were seen in
the dieldrin and phenobarbital treated rats, in the appearance of
lipospheres in the hepatic cells, and the progressive marked
accumulation of vesiculated smooth endoplasmic reticulum. Striking
increases in the hydroxylation activities of liver microsomes were
seen after only four days on the test diet. Examination of single
animals suggested that the ultracellular hepatic structure had
returned to normal 14 days after removal from the test diet, and that
the microsomal hydroxylation activity was not different from controls
after 28 days (Hunter, 1967).
A three generation reproduction study was conducted, with groups of 10
males and 20 females, and two litters produced per generation, at
dietary levels of 0, 0.1, 1 and 2 ppm of dieldrin. Successive
generations were composed of second litter animals. Parental animals
in each generation were examined grossly and complete autopsies with
histological examination were performed on selected 21 day old F3b
animals. Twenty-one day mortality was significantly raised in the F1a
pups at the 2 ppm level. No effect was seen at other levels or in
other generations at 2 ppm, nor was any adverse effect seen in general
appearance and behaviour, number of litters produced, average number
of pups per litter, weights of parents and offspring, organ weight
ratios and organ pathology, at any level (Hine, 1967).
Groups of five males and five females were fed 3 and 10 ppm of the
photoisomerization product of dieldrin for up to one month without
apparent ill-effect. The biological half-life of the product was
calculated to be 1.7 and 2.6 days for male and female rats,
respectively, and the fat storage ratios were 0.45-0.47 and 0.76-1.8
respectively (Brown et al., 1967)
Monkey. Groups of five male rhesus monkeys (with one female added to
the control group) were fed 0, 0.01, 0.1, 0.5, 1 and 1.5-5 ppm of
dieldrin for 36 months. The study was continuing. The highest level of
feeding was started at 5 ppm and was reduced to 2.5 ppm after 4
months, and then to a calculated 1.75 ppm at the 9th month. Two
animals died in this group, the first in the 4th month, with no cause
attributed at post mortem (liver content of dieldrin, 10 ppm, muscle
content 2.2 ppm); and the second died in the 6th month of "endocrine
failure", with a dieldrin content of 9.4 ppm in the brain and 0.15 ppm
in whole blood. The intake in a surviving animal from this group was
then progressively increased to 5 ppm. One monkey in the 1.0 ppm group
had a progressive anaemia. Blood samples from all groups showed
evidence of the presence of pyrethrum and piperonyl butoxide, a
formulation used in the laboratory for pest control. Use of the
formulation was then discontinued (Zavon, 1966; Zavon et al., 1967).
Dog. Groups of five males and five females, plus two supplementary
animals of each sex at each dose level for EEG recording were given
daily doses of 0.005 and 0.05 mg/kg/day of dieldrin for 52 weeks. The
study was scheduled to continue for 2 years. Plasma alkaline
phosphatase activity was significantly elevated in the high dose group
from the 30th week. There was no difference in BSP retention between
this group and the controls. No differences in general appearance or
haematogical findings were noted between the groups. It is believed
that whole blood levels of dieldrin in the 0.005 mg/kg/day group
stabilized between the 12th and 18th weeks at around 0.008 ppm. Whole
blood levels in the 0.050 mg/kg/day group had risen to about 0.05 ppm
by the 18th month and remained somewhat slightly below that level
(Hunter, 1966; 1967).
Dog. A lifetime feeding study on dieldrin had been in progress for
253 weeks, using one male and one female at 0 and 0.2 mg/kg/ body
weight/day. Plasma alkaline phosphatase activity was greatly elevated
in the test animals at 134 and 215 weeks.
Whole blood dieldrin content is reported to have peaked at about the
50th week in the test animals to about 0.4-0.5 ppm and by the 225th
week was down to 0.065-0.08 ppm. No difference between groups had been
seen in general health and behaviour, haematology, BSP retention and
examination of urine (Hunter, 1966; 1967).
Observations in man
Groups of three adult males were given daily doses of 0, 0.01, 0.05
and 0.21 mg of dieldrin for 18 months. None of the subjects showed
signs of ill health and the results of clinical observations,
measurement of serum alkaline phosphatase and erythrocyte and plasma
cholinesterase activities, EEG and ECG recordings and
electromyographic studies remained within normal limits during the
test period. The blood and adipose tissue concentrations of dieldrin
were found to be proportional to the daily dose, and it was believed
that concentration equilibria were reached in the blood and adipose
tissues during the 10th to the 18th months and the 9th and the 15th
months respectively. It was concluded that the ratio of concentration
in blood to concentration in the fat is about 1:156. The average
adipose tissue concentration at the high level was 2.15 ppm vs. 0.21
ppm in the subjects before the test period. During this period no
significant changes in tissue concentrations of DDT or DDE were seen
(Hunter and Robinson, 1967).
Additional studies have shown that dieldrin produced no adverse effect
in man given 0.2 mg/day for 18 months, and that 1.0 ppm was a no
effect level in the monkey fed this amount for 36 months. However,
studies have reflected a possible tumorigenic effect in mice. Also,
there is a recent finding of a photoisomeration product of dieldrin,
and for which no long-term toxicity studies have been reported. The
Committee therefore adhered to the toxicological evaluation published
in the last report1 which is repeated below.
Estimate of acceptable daily intake for man
0 - 0.0001 mg/kg body weight2
Further work required
Adequate data on the tumorigenic potential of dieldrin
Toxicological studies on the photoisomerization product of dieldrin
See also General Comments p. 3 and 4.
EVALUATION FOR TOLERANCES
RESIDUES RESULTING FROM SUPERVISED TRIALS
Seed treatment of vegetable and grain crops leads in general to
insignicant residues in the crop (0.02 ppm or less). (CCPR 1967a).
FATE OF RESIDUES
Roburn, 1963, reported on an unknown compound on dieldrin-treated
grass. This product is also formed by UV-irradiation on glass plates.
Other unidentified compounds are formed as by-products (Scharf, 1963).
Preparation of dieldrin conversion products in solution was described
by Bird, 1961.
1 FAO, PL:CP/15; WHO/Food Add./67.25
2 Sum of aldrin and dieldrin by weight.
The main irradiation product of dieldrin - called U.V.C.P. or P.I.P.D.
occurs occasionally and in very small amounts.
Concentration of P.I.P.D. in the Environment (Robinson at al. 1966)
Nature of Sample Average concentration Detection HEOD in
of P.I.P.D. in ppa limit ppm
English mutton fat 0 - 0.004 0.001 0.07
Australian mutton fat none detected 0.0001 0.01
Argentine corned beef 0 - 0.0018 0.002 0.015 - 0.16
Crude edible oils
and fats none detected 0.004 - 0.05 0.05
Whole cooked meals none detected 0.001 0.02
Human fat (pooled) none detected 0.00005 0.4
Shag eggs (pooled) none detected 0.0001 2.1
Forage beet foliage 0.02 0.09
Although P.I.P.D. is more toxic to some species than is HEOD (Brown et
al, 1967), from these concentrations of P.I.P.D. it is tentatively
concluded that the possible conversion of dieldrin by sunlight does
not lead to significant increase of residues arising from use of
The average dietary intake of dieldrin per person per day in the
U.S.A. based on a food consumption rate of 4.4 kg per day is as
milligrams mg/kg body-weight
1964-5 1965-6 1966-7 1964-5 1965-6 1966-7
aldrin 0.001 0.002 0.001 0.00001 0.00002 0.00001
dieldrin 0.005 0.007 0.004 0.00007 0.00009 0.00006
Limited studies in southern England indicate the average dietary
intake per person to be nearly 20 micrograms per day. (Robinson and
McGill, 1966). Intake/person/day by air is about 0.2 micrograms and by
drinking water 0.1 micrograms. The following table gives a survey of
estimated daily intake and storage of dieldrin in occupationally
exposed workers after an average of 2,562 hours of exposure (Hayes
Plasma Fat Urine
Storage (ppm) 0.0411 9.48 0.024 (excreted)
Intake (mg/man/day) 1.00 1.10 0.72
Storage (ppm) 0.0019 0.29 0.0008 (excreted)
Intake (mg/man/day) 0.025 0.025 0.025
The following table shows the average concentration of dieldrin in
body fat of the general population in various countries :
Country Year Storage level References
U.S.A. 1961-1962 0.15 )
U.S.A. 1962-1963 0.11 )
U.S.A. 1964 0.31 )
U.K. 1961-1962 0.21 ) Hayes, 1966
U.K. 1963-1964 0.26 )
U.K. 1964 0.21 )
India 1964 0.04 )
France 1960-1961 - Hayes and Dale, 1963
Holland 1964 0.15 Wit, 1964
Australia 1962-1963 0.05 Bick, 1967
W. Germany 1960 n.d. Maier-Bode, 1960
Belgium 1966 n.d. Maes, 1966
New Zealand 1966 0.27 Brewerton, 1967
Metabolism of dieldrin in higher plants still has not been reported.
Matsumura and Boush, 1967, isolated 10 Pseudomonas, Trichoderma and
Bacillus sp. strains with high dieldrin-metabolizing activity from
various insecticide-treated soils and found metabolism rates up to 88
per cent. Aspergillus and Penicillium (Korte et al, 1962) as well as
other fungi and Actinomycetes (Chacko et al, 1966) did not metabolize
Dieldrin is metabolized like aldrin by mammals (Mörsdorf et al, 1963;
Korte et al, 1963; Brooks, 1966; Korte et al, 1966; Richardson et al,
1967) to less toxic hydrophilic products which are excreted in faeces
and urine. In animals this process at a given intake level results in
the establishment of an equilibrium storage level.
Repeated daily doses of 4.3 micrograms of aldrin-C14 (equivalent to
0.2 ppm in the diet) to male rats leads to a saturation level which
reaches a value as high as 0.15 ppm in the body. After 50 days,
approximately the entire activity administered daily was also excreted
daily which means that a saturation level was reached by that time.
Subsequent oral doses did not lead to a higher concentration of the
total insecticide in the rat. Up to 70 per cent of the activity found
in the faeces and up to 95 per cent of that found in the urine
consisted of metabolites. After administration ceased, the
concentration in the body declined rapidly. Half the activity present
had been excreted, mainly as metabolites, after 10 days and three
quarters after 21 days. The time required to reach saturation is
somewhat longer for female rats and the rate of decline is slower
(Korte et al, 1963).
Dieldrin is readily taken up by fish (bluegill and goldfish), and more
than 80 per cent eliminated during a recovery period of two weeks
(Gakstatter et al, 1967).
Determination of residues in liver, meat and fat of sheep, both after
various pre-grazing intervals and after various grazing periods
following pasture treatment with dieldrin, showed that a suitable
combination of pre-grazing interval and grazing period can be
established, which will lead to negligible residues (CCPR 1967a).
However, prior to 1966, mean residues of dieldrin in mutton fat in
Great Britain were 0.4 ppm, caused by sheep dipping. Dieldrin residues
in butter from Australia, Denmark, New Zealand and the United Kingdom
were in the range from 0.01 to 0.03 ppm; in beef kidney fat from
Argentina 0.15 ppm and from the United Kingdom 0.04 ppm (Report of the
Government Chemist, 1964, 1965, 1966).
Feeding studies with poultry, using very high dosages of dieldrin,
have shown that under such conditions depot fat and egg residues
occur. A study of residues under practical intake conditions has not
been reported (CCPR, 1967a).
In storage and processing
Under some conditions of usage, dieldrin residues can appear in
oil-producing crops, such as soybeans, cotton seed etc. All such crops
can be processed using methods which effectively eliminate the residue
from the oil and meal products (Smith et al, 1967). Viel et al, 1967,
reported a 75 per cent reduction of residues by peeling and processing
carrots. The first carbonation juice in processing sugar beets
contained only 1.3 to 3.6 per cent of the residues originally present
in the beets (Walker et al, 1965). Generally it has been shown that
residue levels of dieldrin are reduced on peeling (Lichtenstein et al,
1965; Stewart et al, 1965). The residue levels of chlorinated
pesticides in potatoes and carrots are reduced up to 90 per cent on
peeling (Robinson and Bush, private communication).
Cooking of a hen carcass in water for three hours reduced the
chlorinated insecticide residue content up to 90 per cent (Liska et
Country Tolerances, ppm Crop
Canada 0.1 asparagus, barley, carrots, celery,
corn, cranberries, eggplants, flax,
grapes, horseradish, oats, onions,
parsnips, peppers, plums, potatoes,
prunes, radishes, red currants, rye,
strawberries, tomatoes, wheat.
0.25 apples, apricots, beets, beet tops,
broccoli, Brussels sprouts, cabbage,
cantaloupes, cauliflower, cherries,
cucumber, gourds, kale, kohlrabi,
lettuce, marrow, muskmelons, peaches,
pears, pumpkins, rutabagas, spinach,
squash, turnips, watermelons, winter
German Federal Republic The residue on edible crops may not exceed the
lower limit of detectability of the analytical
Netherlands 0.1 * fruit and vegetables
aldrin and dieldrin
* The Netherlands tolerances listed in the Residue
decree include the toxic metabolites and breakdown
products. In the case of aldrin, dieldrin is
considered as the main metabolite. In consequence
of this a residue of aldrin + dieldrin together may
not exceed the 0.1 ppm level.
Country Tolerances, ppm Crop
Sweden 0.1 fresh fruits, fresh berries,
dieldrin vegetables including potatoes.
Switzerland 0.1 potatoes
U.S.A. Tolerances are for total residues of aldrin and
its epoxide dieldrin, resulting from the
application of aldrin or dieldrin in or on raw
0.1 in or on apples, apricots, asparagus,
aldrin and bananas, broccoli, Brussels sprouts
dieldrin cabbages carrots, cauliflower,
cherries, cranberries, cucumbers,
eggplants, grapes, horseradish,
lettuce, mangoes, nectarines, onions,
parsnip, peaches, pears, peppers,
pimentos, plums (fresh prunes),
potatoes, quinces, radishes, radish
tops, salsify roots, strawberries,
summer squash, sweet potatoes,
zero in or on alfalfa, beans, black-eyed
peas, cantaloups, clover, collards,
corn grain, corn forage, cowpeas,
cowpea hay, endive (escarole), garden
beets, garden beet tops, grain sorghum,
grain sorghum forage, kale, kohlrabi,
lespedeza, mustard greens, peas, pea
hay, popcorn, rutabagas, salsify tops,
spinach, soybeans, soybean hay, Swiss
chard, turnips, turnip tops.
Additional tolerances for residues of
dieldrin are established, on an interim
basing pending referral to an advisory
0.1 in or on stray of barley, oats, rye
0.05 in or on grapefruit, lemons, limes,
oranges and tangerines.
0.02 in or on grains of barley, oats, rye
RECOMMENDATIONS FOR TOLERANCES AND PRACTICAL RESIDUE LIMITS
Since the 1966 FAO/WHO Joint meeting, the first extensive data on
total diet studies (Duggan, 1967) have become available from the
U.S.A. showing that the actual intake of aldrin and dieldrin is about
60 times lower than that calculated from the tolerances established in
In the light of the new data presented at this meeting, the temporary
tolerances listed in the following table are recommended for combined
residues of aldrin and dieldrin in commodities moving in international
Commodity Temporary tolerance, ppm
Fresh vegetables 0.1
(from intentional and approved
use) and in so far as aldrin or
dieldrin have to be and are
allowed to be used in individual
countries on specific crops within
Fresh fruits 0.1
The recommended temporary tolerances are based on the requirements for
good agricultural practice and are of the same order of magnitude as
those in effect at present in the U.S.A.
Practical residue limits
The meeting noted the comments made by some member countries of the
Codex Committee on Pesticide Residues (CCPR, 1967b) on needs for
practical residue limits, but did not have data available on the
actual residues in these products from most of the countries
concerned. However, in a review of previous actions, the meeting
agreed to recommend a temporary revision as follows :
Total Combined Residue
Aldrin plus Dieldrin, ppm
Cereal grains (except rice) - 0.02
Milk, whole - 0.005
Total Combined Residue
Aldrin plus Dieldrin, ppm
Milk products (fat basis) - 0.125
Meat (fat basis) - 0.2
In the absence of experimental residue data, the meeting did not
recommend practical residue limits for egg yolk, a subject which has
to be reconsidered when new data are available.
Further work required before 30 June 1972
Data should be provided by countries on residues actually being found
in various foods.
Further work desirable
The fate of both aldrin and dieldrin should be reinvestigated,
including metabolism of these insecticides in plants. Additional data
on food residues outside the U.S.A, would be useful to include residue
data in egg yolk and meat. A continuing study of human fat residues
and actual human intake is desirable.
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