CHLORPYRIFOS JMPR 1975 Explanation Chlorpyrifos was considered by the Joint Meeting in 1972 and an ADI was established (FAO/WHO, 1973). Based on information reported at that Meeting and at the 1974 Meeting (FAO/WHO, 1975), a number of further recommendations for tolerances were specified on both animal and vegetable products. During the CCPR Meeting 1975 some delegations expressed opinions on individual tolerances reflecting different views on good agricultural practices, and specific levels established for poultry fat and for milk were questioned. As no information has been received concerning residues in vegetable products, the Meeting has only considered the questions raised on poultry fats and milk products. RESIDUES IN FOOD AND THEIR EVALUATION In poultry fat A chicken feeding study by Dishburger et al. (1972) which has been brought to the attention of the Meeting elucidates the question of chlorpyrifos residues in poultry fat further. In this study laying hens were fed chlorpyrifos at rates of 0.3, 1.0, 3.0 and 10 mg/kg for 30 days. Samples of muscle (with fat and skin), liver, kidney and peritoneal fat were analysed, as were eggs from hens fed 10 mg/kg over a period of 45 days. Chlorpyrifos and 3,5,6-trichloro-2-pyridinol were determined (see Table 1) and analysis showed that the level of the parent compound in chicken fat is not likely to exceed 0.1 mg/kg under practical circumstances following good agricultural practices. Residues of chlorpyrifos in eggs were not detectable. Another source of chlorpyrifos residues in poultry fat was reported earlier (FAO/WHO, 1973), namely the more specific practice of controlling chiggers, Neschongastia americana in turkeys through soil-treatments in pens. As a result of this application some of the compound is take up by the turkeys and maximum residues of 0.157 and 0.066 mg/kg in skin and fat respectively were found one week after the treatment (Claborn et al., 1970) declining to less than 0.001 mg/kg after six weeks. While the earlier recommendation of 0.2 mg/kg for chlorpyrifos in poultry fat could therefore be lowered to 0.1 mg/kg as far as chicken fat is concerned, this would not be justified in the case of turkey fat and skin. TABLE 1. Average residues of chlorpyrifos and 3,5,6-trichloro-2-pyridinol in tissues and eggs of chickens fed chlorpyrifos Average residues found, mg/kg Chlorpyrifos 3,5,6-trichloro-2-pyridinol Chlorpyrifos level in feed mg/kg Muscle Liver Kidney Fat Eggsa Muscle Liver Kidney Fat Eggsa 0 - - - - - - - - - - 0.3 - - - - - - ND ND - - 1.0 - - - ND - - ND ND-0.11 - - 3.0 - - - ND-0.02 - - ND-0.06 ND-0.24 - - 10.0 ND ND ND 0.02-0.06 ND ND ND-0.25 ND-0.84 ND ND-<0.05 10.0b - - - ND - - ND ND - - a Eggs collected from chickens on treated feed 7-45 days - no withdrawal period. b 7-day withdrawal from medicated feed. In milk and milk products Studies of the transfer of chlorpyrifos into milk after feeding cows at the 5 mg/Kg level and reports on milk residues resulting from single dip applications were evaluated by the JMPR 1972 and no new information has become available. In response to the question raised by the CCPR, the Meeting reconsidered the data already available and recognized that the previous recommendation reflects only the reported feeding studies, whereas residues arising from direct dip applications (Table 5 of FAO/WHO 1973) may not be sufficiently covered by the established maximum residue limit of 0.01 mg/kg. Taking into account the increasing use and potential interest in such applications, a maximum residue of 0.1 mg/kg is required. In proposing this limit the Meeting recognized that the milk from treated cows will, in normal practice, be blended with milk from untreated cows and that it would be unlikely for more than a proportion of commercial milk to come from recently treated cows, even in areas where treatments have to be repeated frequently (FAO/WHO, 1972). APPRAISAL In response to questions raised by the Codex Committee on Pesticide Residues, the Meeting has reconsidered the earlier established tolerances for chlorpyrifos in poultry fat and milk. Based on new information from chicken feeding studies, the earlier recommended tolerance of 0.2 mg/kg in poultry fat could be lowered to 0.1 mg/kg as far as chicken fat is concerned. However, the earlier recommendation should be maintained to account for the higher residues in fat and skin of turkeys which may arise from soil treatments in turkeys' pens in the control of chiggers. Having re-evaluated the earlier recommendation for a tolerance of 0.01 mg/kg for chlorpyrifos in milk (fat basis), the Meeting agreed that this level was not adequate to cover residues which may result from dip applications to dairy cattle. An increase of the earlier proposal to 0.1 mg/kg is appropriate. RECOMMENDATIONS Earlier established tolerances (FAO/WHO, 1973, 1975) should be amended as follows, by deleting tolerances for fat of poultry and for milk and inserting: Commodity Maximum residue limit, mg/kg Fat and skin of turkey 0.2 Fat of chicken 0.1 Milk and milk products (fat basis) 0.1 Eggs (whole) 0.01* * At or about the limit of determination. REFERENCES Claborn, H. V., Kunz, S. E. and Mann, H. D. (1970) Residues of Dursban in the body tissues of turkeys confined in pens containing treated soils. J. Econ. Entomol., 63:422-424. Dishburger, H. J., McKellar, R. L. and Wetters, J. H. (1972) Residues of chlorpyrifos and 3,5,6-trichloro-2-pyridinol in tissues and eggs from chickens fed chlorpyrifos. Report from Dow Chemical USA, Midland, Michigan, 31 May.
See Also: Toxicological Abbreviations Chlorpyrifos (ICSC) Chlorpyrifos (WHO Pesticide Residues Series 2) Chlorpyrifos (Pesticide residues in food: 1977 evaluations) Chlorpyrifos (Pesticide residues in food: 1981 evaluations) Chlorpyrifos (Pesticide residues in food: 1982 evaluations) Chlorpyrifos (Pesticide residues in food: 1983 evaluations) Chlorpyrifos (JMPR Evaluations 1999 Part II Toxicological)