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 PARATHION This pesticide was evaluated toxicologically in 1965 (FAO/WHO, 1966b) when an acceptable daily intake was established. Following a review in 1967 (FAO/WHO, 1968b) some temporary tolerances were recommended and the Meeting asked for further information by 30 June 1970. With a view to a removal of the 'temporary' qualification to the recommendation, data were required on: (a) residues resulting from pre-harvest treatment of cereals and the fate of parathion in storage and processing, (b) residues in cottonseed oil and cotton cake, (c) residues found in total diet studies. Further work was considered desirable, on: (a) the occurrence of the oxygen analogue in plants, (b) the metabolism of the amino analogue, e.g. in ruminants, (c) the presence of residues in food commodities moving in commerce. RESIDUES IN FOOD AND THEIR EVALUATION FATE OF RESIDUES Parathion was found in only one sample in a twelve-month study of whole diets in England and Wales (Abbott et al., 1970); this was present in the fats group at 0.01 ppm and therefore at a much lower level in the total diet. It is clear from the degradation curves for parathion and paraoxon on lettuce published by Möllhoff (1968a) that the half-life of the oxon is much shorter than that of the thion, and that the oxon, if formed, will not tend to accumulate. This author also reports studies on field lettuce sprayed with parathion, analysing with a GLC method using a phosphorous-sensitive detector with-limits of 0.01 ppm for parathion and 0.02 ppm for paraoxon. The residue of parathion fell from 1.74 ppm to 0.02 ppm in 14 days. Paraoxon was present only at the limit of detection on the day of spraying, but was not detectable thereafter. Later reports by Möllhoff (1968b) concerning spinach show that material picked on the day of spraying contained 1.5 ppm parathion and 0.05 ppm paraoxon. However, if the material was sterilized by heating to 115°C during the storage period, paraoxon was degraded to undetectable levels. Spinach gathered 29 days after spraying had no detectable residue of either parathion or paraoxon. Abbott et al. (1970) did not detect paraoxon in any sample in their whole-diet studies. Evidence of residues in food in commerce Analyses of fruit and vegetables entering commerce in the German Federal Republic (Krause and Kirchhoff, 1969) showed that only 14 out of 228 samples contained measurable amounts of parathion (>0.01 ppm). In most of these cases, the residue was less than 0.1 ppm, but two samples of lettuce bore 0.15 and 1.5 ppm, respectively, and one of parsley bore 0.4 ppm. APPRAISAL Total diet studies over a year in England and Wales have shown that parathion was absent from all classes of food except fats, in which it was present to the extent of 0.01 ppm on one occasion. The oxygen analogue, paraoxon, has a much shorter persistence on or in plant material than parathion. It was detected on lettuce on the day that parathion was applied but not thereafter. It was also detected in spinach on the day that parathion was applied, but was not detectable when the crop was harvested a month later. It was not detected in the whole-diet studies conducted over a year in England and Wales. Parathion was present in measurable amounts in only 14 out of 228 samples of vegetable and fruits in West Germany; in most of these cases, the level was less than 0.1 ppm, but this level was exceeded in two samples of lettuce and one of parsley. It was agreed that no justification exists for the grouping together of parathion and parathion-methyl for tolerances. RECOMMENDATIONS FOR TOLERANCES There are no grounds for changing the figures recommended by the 1969 Joint Meeting, but the 'temporary' qualification can now be withdrawn. The recommendations therefore are for tolerances, which are as follows: Vegetables (except carrots) 0.7 ppm Peaches, apricots, citrus fruits 1.0 ppm Other fresh fruits 0.5 ppm FURTHER INFORMATION REQUIRED (before tolerances can be recommended for these products) 1. Data on residues resulting from pre-harvest treatment of cereals. 2. Data on residues in cotton seed, seed oil and seed cake. 3. Data on the fate of parathion in storage and processing in the above mentioned products. 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. Organophorphorous pesticides residues in the total diet. Pestic. Sci.,1: 10-13 Krause, C. and Kirchhoff, J. (1969) Organophosphat - Rückstände auf Marktproben von Obst und Gerüse sowie auf Getreideerzeugnisson. Nachrichtenblatt d. Deutschen Pflanzenschmtz - dienst., 21: 81-84 Müllhoff, E. (1968a) Contribution to the question of residues and their determination in plants treated with (R) E605 and (R) Agnitox. Pflanzenschmtz - nachrichten Bayer, 21: 327-354 (English Edition) Möllhoff, E. (1968b) Pflanzenschmtzmittel-Rückstände. Internal reports, Biologisches Institut der Farbenfabriken Bayer AG, Leverkusen, 55/132, no. 27 a-d/68
See Also: Toxicological Abbreviations Parathion (HSG 74, 1992) Parathion (ICSC) Parathion (FAO Meeting Report PL/1965/10/1) Parathion (FAO/PL:1967/M/11/1) Parathion (FAO/PL:1969/M/17/1) Parathion (Pesticide residues in food: 1984 evaluations) Parathion (Pesticide residues in food: 1995 evaluations Part II Toxicological & Environmental) Parathion (IARC Summary & Evaluation, Volume 30, 1983)