AGP:1970/M/12/1
WHO/FOOD ADD/71.42
1970 EVALUATIONS OF SOME PESTICIDE RESIDUES IN FOOD
THE MONOGRAPHS
Issued jointly by FAO and WHO
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
Group on Pesticide Residues, which met in Rome, 9-16 November, 1970.
FOOD AND AGRICULTURE ORGANIZATION OF THE UNITED NATIONS
WORLD HEALTH ORGANIZATION
Rome, 1971
MALATHION
Explanation
This pesticide was evaluated by the 1966 Joint Meeting (FAO/WHO, 1967)
which established the acceptable daily intake for man. Modifications
in the recommended tolerances were made by the 1967 Joint Meeting
(FAO/WHO, 1968), the 1968 Joint Meeting (FAO/WHO, 1969) and the 1969
Joint Meeting (FAO/WHO, 1970).
In the Report of the 1969 Joint Meeting, the following information was
"Required before 30 June 1970":
1. Residues in fruit and vegetables following uses in accordance with
good agricultural practice in different countries.
2. The minimum periods likely to pass between application and/or
harvesting and the time the tolerance is to be applied in different
countries.
RESIDUES IN FOOD AND THEIR EVALUATION
RESIDUES RESULTING FROM SUPERVISED TRIALS AND IN FOOD, IN
COMMERCE OR AT CONSUMPTION
In strictly supervised trials by the Agricultural Research service of
the United states Department of Agriculture vegetables and fruits were
treated at the maximum recommended rates, with the 57% E.C.
formulation, and duplicate samples taken for analysis on the day the
last application was made, and also after the recommended U.S.A.
harvest interval. Samples were analysed by GLC for malathion and
malaoxon using a flame photometric detector with a 560 nm filter;
those taken at zero day were analysed both in the raw state and after
washing in cold running water, and after washing and cooking according
to 'home practice'. No malaoxon was detected in any sample; the
results for malathion are given in Table I.
Although the studies carried out in the U.S.A. by the National Canners
Association (Farrow et al., 1968) agree that washing by 'home
procedure' removes very little malathion from tomatoes, commercial
washing procedures were shown to remove 84 to 95 percent of the
residue. Canned tomatoes or tomato juice contained less than 1 percent
of the malathion present in the original samples, whether processing
was by commercial or 'home' methods. In a parallel study on
field-sprayed green beans (Elkins et al., 1968), only a trace (< 0.05
ppm) was found, regardless of the method of conservation.
In a 12-month study based on 66 samples of food in total diets in
England and Wales, Abbott et al., (1970) found malathion more often
than any other organophosphorus compound. Even so, it was confined to
three of the seven groups within the dietetic range, being found
twelve times in cereal samples (0.01 to 0.04 ppm, mean 0.02 ppm),
TABLE I
Malathion residue study (K.R. Hill et al., 1970)
Crop No. of Rate Sampling Harvest day
applic. (kg a.i./ha) intervals Zero day samples (ppm) samples (raw)
(days) Raw Washed Washed & (ppm)
cooked
Lettuce Weekly
(5 weeks)
" leafy 2.25 14 25.5 10 6.6 0.0
25.5 14 6.6 0.0
" head 2.25 7 27 7.5 3.8 0.19
28 10.5 3.8 0.18
Spinach Weekly 2.25 7 6.5 3.9 1.6 0.14
(5 weeks) 6.7 3.2 2.2 0.13
Cabbage Weekly 2.82 7 5.5 1.8 1.7 0.94
(5 weeks) 4.6 2.0 1.5 0.81
String Weekly 2.25 1 0.8 0.4 0.3 0.48
beans (6 weeks) 0.8 0.5 0.3 0.48
Tomatoes Weekly 2.25 1 0.35 0.35 0.05 0.3
(4 weeks) 0.35 0.35 0.05 0.3
Cherries Twice 9.0 3 4.8 3.4 2.0 0.4
6.0 4.5 4.0 0.2
Peaches 3 times 10.1 7 1.3(0.06)1/ 0.25 (0.0) 0.04(0.0)
1.1(0.05) 0.22 (0.0) 0.04(0.0)
1/ Figures in parentheses are for peeled fruit
twice in green vegetables (0.01 and 0.03 ppm) and once in fruit and
preserves (0.01 ppm).
NATIONAL TOLERANCES
The data in Table 1 indicate that no difficulty would be experienced
in meeting even the German tolerances, indicated below, providing the
harvest intervals are observed.
ppm
Crop U.S.A. German
Lettuce, spinach,
cabbage, string beans 8 3
Tomatoes, cherries,
peaches 8 0.5
APPRAISAL
RECOMMENDATIONS FOR TOLERANCES
Information from studies in the U.S.A. and from a compilation of
commercial trials data indicates that the following revised tolerances
can be recommended. These recommendations assume that the intervals
specified between the last application and harvest have been observed:
Crop Interval between Recommendation for tolerance
last application (ppm)
and harvest
(days)
Blackberries,
raspberries 1 8
Grapes 3 8
Cherries 3 6
Peaches, plums 7 6
Apples 7 2
Strawberries 1 1
Blueberries 1 0.5
Pears 7 0.5
Crop Interval between Recommendation for tolerance
last application (ppm)
and harvest
(days)
Lettuce,
endive,
cabbage,
spinach 7 8
Broccoli 3 5
Kale, turnips 7 3
Tomatoes 1 3
Beans (green) 1 2
Celery 7 1
Cauliflower,
peas (in pod),
peppers,
eggplant 3 0.5
Roots
(except
turnips),
Swisschard,
collards,
kohlrabi 7 0.5
The rate of breakdown of malathion is sufficiently fast to ensure that
residues will decrease rapidly with time. They will also be
substantially reduced by commercial washing procedures, for example
85-95 percent tomatoes. Canned tomatoes have been shown to contain
less than 1 percent of the residue present before canning. Washing,
blanching and cooking of broccoli, kale, spinach and other green
vegetables has been found to reduce the residue level by more than 90
percent.
This information is considered to meet the requirement set at the 1969
Joint Meeting.
REFERENCES
Abbott, D.C., Crisp, S., Tarrant, K.R. and Tatton, J.O'G (1970)
Pesticide residues in the total diet in England and Wales, 1966-1967.
III.-Organophosphorus pesticide residues in the total diet. Pestic.
Sci., 1: 10-13
Elkins, E.R. Lamb, F.C., Farrow, R.P., Cook, R.W. Kawai, Margaret and
Kimball, J.R. (1968) Removal of DDT, malathion, and carbaryl from
green beans by commercial and home preparative procedures.
J. agr. Fd Chem., 16: 962-966
Farrow, R.P., Lamb, F.C., Cook, R.W., Kimball, J.R. and Elkins,
E.R.(1968) Removal of DDT, malathion, and carbaryl from tomatoes by
commercial and home preparative methods. J. agr. Fd Chem., 16: 65-71
Hill, K.R. Report of residue analysis. PCB-70-6 (U.S. 1970 official
report. Publication in preparation)
See Also:
Toxicological Abbreviations
Malathion (ICSC)
Malathion (FAO Meeting Report PL/1965/10/1)
Malathion (FAO/PL:CP/15)
Malathion (FAO/PL:1967/M/11/1)
Malathion (JMPR Evaluations 2003 Part II Toxicological)
Malathion (FAO/PL:1968/M/9/1)
Malathion (FAO/PL:1969/M/17/1)
Malathion (WHO Pesticide Residues Series 3)
Malathion (WHO Pesticide Residues Series 5)
Malathion (Pesticide residues in food: 1977 evaluations)
Malathion (Pesticide residues in food: 1984 evaluations)
Malathion (Pesticide residues in food: 1997 evaluations Part II Toxicological & Environmental)
Malathion (IARC Summary & Evaluation, Volume 30, 1983)