FAO, PL:CP/15
WHO/Food Add./67.32
EVALUATION 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 and the WHO Expert Committee on
Pesticide Residues, which met in Geneva, 14-21 November 1966.1
1 Report of a Joint Meeting of the FAO Working Party and the WHO
Expert Committee on Pesticide Residues, FAO Agricultural Studies, in
press; Wld Hlth Org. techn. Rep. Ser., 1967, in press
DIAZINON
This pesticide was evaluated by the Joint Meeting of the FAO Committee
on Pesticides in Agriculture and the WHO Expert Committee on Pesticide
Residues in its 1965 report (FAO Meeting Report No. PL/1965/10/1;
WHO/food Add./27.65). Since its publication some new experimental work
has been reported on this compound. This new work is presented and
discussed in the following monograph addendum.
BIOLOGICAL DATA AND TOXICOLOGICAL EVALUATION
Short-term studies
Monkey. Groups, each of 3 male and 3 female monkeys (species
unstated) were given daily oral doses of 0.05, 0.5 and 5.0 mg diazinon
per kg body-weight for 2 years. The control animals generally showed a
slightly greater weight gain than the treated animals and the signs
noted were periodic soft stools, seen noticeably in the middle and
high dosage levels, and hyperaesthesia, recorded for one low level and
one high level monkey. Cholinesterase determinations showed no
significant inhibition of erythrocyte or plasma cholinesterase
activity at the 0.05 mg/kg/day level, though this did occur at the
higher levels of feeding and there was a dose-response relationship
(Geigy, 1966).
Man. When 2 adult males were given daily doses of approximately
0.025 mg/kg diazinon for 5 days, the plasma cholinesterase, but not
the erythrocyte cholinesterase, showed a marked reduction as compared
with pre-test levels. Then, 4 adult males were given daily doses of
about 0.025-0.030 mg/kg diazinon for 32-34 days. There was no
significant change in either plasma or erythrocyte cholinesterase
levels, nor in the serum phosphatases, blood picture, clot elasticity,
recalcification times, sedimentation rate or in the urine (Geigy,
1966)
Three adult males were given daily doses of 0.05 mg/kg diazinon for 5
days, allowed to recover for 23 days and then the same dosing regime
was resumed for 5 days. Plasma cholinesterase activity was depressed
to about 60-65 per cent of pre-test levels. Then groups of 3 adult
males were given daily doses of 0 and 0.025 mg/kg diazinon for 43
days. Plasma cholinesterase activity in the test group was about 80-85
per cent of the control, but there was no depression in that of the
erythrocytes. Finally, 3 adult males were given 0.020 mg/kg diazinon
daily for 37 days. By the second week, plasma cholinesterase activity
was about 86 per cent of the pre-test level without any change in that
of the erythrocytes. During none of these tests was there any
alteration in blood haemoglobin levels, haematocrit, blood cell
counts, prothrombin and clotting times, serum alkaline phosphatase and
glutamic pyruvic transaminase activities, blood urea, urinary
constituents or body-weight. Nor were any symptoms experienced (Ind.
Biotest. Lab., 1966)
Comments
More information is desirable about the metabolism and fate of
diazinon in the body, especially in man.
The studies made on man to ascertain the minimum dose for
cholinesterase depression are valuable, but it would be helpful if
they could be extended to more subjects, especially females.
Reproduction and long-term experiments with diazinon in animals would
be desirable.
TOXICOLOGICAL EVALUATION
Levels causing no toxicological effect
Rat 2 ppm in the diet, equivalent to 0.10 mg/kg/day
Dog 0.02 mg/kg/day
Monkey 0.05 mg/kg/day
Man 0.02 mg/kg/day
Estimate of acceptable daily intake for man
0.002 mg/kg body-weight
REFERENCES
Geigy, J. R., S. A. (1966) Unpubl. report submitted to WHO
Industrial Biotest Laboratories, Inc. (1966) Unpubl. report submitted
to Geigy.