1970 EVALUATIONS OF SOME PESTICIDE RESIDUES IN FOOD
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
This compound was evaluated by Joint Meetings in 1966, 1967, 1968 and
1969 (FAO/WHO, 1967b, 1968b, 1969b and 1970b). A temporary acceptable
daily intake for man of 0.01 mg/kg was proposed in 1969, to be
reviewed in 1973. In 1969, temporary tolerances proposed in 1967 and
others added in 1968 were revised and extended, but that proposed in
1968 for whole milk was withdrawn.
Further information required by 30 June 1970 included: (a) results
from total diet studies, (b) data on residue levels in whole milk, (c)
data on the disappearance of residues during storage and processing of
cocoa beans and derived products and of cereals into cereal products,
More sensitive methods of analysis, especially for total diet studies,
were considered desirable.
RESIDUES IN FOOD AND THEIR EVALUATION
Results of studies on dietary intake in the U.S.A. have been
summarized by Duggan and Lipscomb (1969). The percentage of total diet
samples containing carbaryl and the daily intake per kg bodyweight
were 7.4 and 0.15 mg in 1965, 2.7 and 0.026 mg in 1966, 1.1 and <0.01
mg in 1967, and were below the limits of measurement in 1968. These
authors concluded that, for diets in the U.S.A., "Carbamate chemicals
and carbaryl do not occur at sufficiently high levels or frequencies
to be considered as contributors to the daily intake of pesticide
No new information has been received concerning residue levels in milk
nor on the fate of residues in storage or processing of cocoa beans or
cereals; items b, c and d of the information requested therefore
Evidence on the effect of simple washing on residue levels on cabbage
and eggplant have been published from India (Mann and Chopra, 1969).
Samples were taken at intervals up to seven days after the fourth
application by spraying of carbaryl in nine-week periods, and half of
these samples on each occasion were washed before analysis. The
spraying rates, intervals between spraying and harvesting, and the
residue levels on unwashed and washed samples are given in Table I.
The temporary tolerance of 5 ppm in poultry set by the 1969 Joint
Meeting on a whole meat basis, including skin, was referred back by
the 5th Meeting of the Codex Committee on Pesticide Residues. Further
data have been provided that show that the distribution of residues
varies considerably with the method of application of carbaryl. The
method of analysis was colorimetric and determined carbaryl and
1-naphthol at 0.1 and. 0.2 ppm, respectively. Residues of 1-naphthol
never exceeded 10% of those of carbaryl. Even when carbaryl was
applied at frequent intervals and rates above those recommended,
Carbaryl residues (ppm) present after spraying1
Picking 0.1% (0.62 kg/ha) 0.2% (1.24 kg/ha) 0.4% (2.48 kg/ha)
(days) unwashed washed unwashed washed unwashed washed
0 14.80 0.97 23.83 1.34 33.86 1.25
1 9.00 2.08 13.33 3.81 18.57 5.61
3 5.72 2.77 8.15 3.41 10.41 5.05
5 3.83 2.88 5.86 2.72 6.99 3.80
7 2.50 1.44 3.94 2.17 5.13 2.94
1 8.33 - 12.22 - 16.86 -
3 5.29 1.98 7.30 3.14 9.85 4.70
5 3.58 1.80 5.08 2.55 6.42 3.38
7 3.05 1.30 4.31 1.99 5.40 2.80
1 A comparison of the rates of dissipation for washed and unwashed
cabbage shows that washing removes the initial deposit readily, but
that carbaryl penetrates into the plant during the first day or two
to a considerable extent. Comparable deposits and penetration occur
on the eggplant.
residues after seven days in tissues other than the skin did not
exceed the limit of measurement. Residues on the skin did not exceed 3
ppm. Since the skin provides about 9% of the total edible tissues, a
temporary tolerance of 0.5 ppm for the edible parts of prepared birds
should be sufficient; the previously recommended figure of 5 ppm
thereby applies only to the skin of poultry.
METHODS OF RESIDUE ANALYSIS
Two methods using GLC with electron capture have recently been
described. In Cohen et al. (1970) recoveries from spiked samples of
lettuce and peas were 82% and 87% respectively, from apples, 94% and
the level of detection in plant material was reported to be 0.1 ppm.
Tilden and Van Middelem (1970) claim a limit of 0.2 ppm, but were
unable to avoid a high reagent blank. These methods seem suitable for
Further information has been received concerning the levels of
carbaryl present in various organs and tissues of laying hens and
turkey poults killed seven days after treatment by various methods of
external application. This indicates that the temporary tolerance of 5
ppm for poultry, recommended at the Joint Meeting in December 1969,
should be adequate for poultry skin, but that the tolerance for
prepared birds, i.e. the total edible portion, including the skin,
could be reduced to 0.5 ppm.
Studies on total dietary intake from the U.S.A. over the period
1965-1968 showed that intake was rapidly decreasing and was below the
limit of determination in the final year. Harvest residue data on
cabbage and eggplant indicate that the recommended tolerance of 5 ppm
should be retained.
Two analytical methods using G.L.C. with electron capture detection
have been described, one reports the lower level of detection to be
FURTHER WORK OR INFORMATION
REQUIRED (before tolerances can be set for whole milk and milk
Further data on residue levels.
Cohen, I.C., Norcup, J, Ruzicka, J.H.A., and Wheals, B.B. (1970) An
electron-capture gas chromatographic method for the determination of
some carbamate insecticides as 2,4-dinitrophenyl derivatives of their
phenol moieties. J. Chromatog., 49: 215-221.
Duggan, R.E., and Lipscomb, G.Q. (1969) Dietary intake of pesticide
chemicals in the United States (II), June 1966 - April 1968. Pestic.
Monit. J., 2 (4): 153-162.
Mann, G.S., and Chopra, S.L. (1969) Residues of carbaryl on crops.
Pestic. Monit. J., 2 (4): 163-166.
Tilden, R.L. and Van Middelem, G.H. (1970) Determination of carbaryl
as an amide derivative by electron-capture gas chromatography. J. Agr.
Food Chem., 18: 154-158.