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.
See Also: Toxicological Abbreviations Diazinon (EHC 198, 1998) Diazinon (ICSC) Diazinon (FAO Meeting Report PL/1965/10/1) Diazinon (FAO/PL:1967/M/11/1) Diazinon (FAO/PL:1968/M/9/1) Diazinon (AGP:1970/M/12/1) Diazinon (WHO Pesticide Residues Series 5) Diazinon (Pesticide residues in food: 1979 evaluations) Diazinon (Pesticide residues in food: 1993 evaluations Part II Toxicology) Diazinon (JMPR Evaluations 2001 Part II Toxicological)