PESTICIDE RESIDUES IN FOOD - 1981 Sponsored jointly by FAO and WHO EVALUATIONS 1981 Food and Agriculture Organization of the United Nations Rome FAO PLANT PRODUCTION AND PROTECTION PAPER 42 pesticide residues in food: 1981 evaluations the monographs data and recommendations of the joint meeting of the FAO panel of experts on pesticide residues in food and the environment and the WHO expert group on pesticide residues Geneva, 23 November-2 December 1981 FOOD AND AGRICULTURE ORGANIZATION OF THE UNITED NATIONS Rome 1982 CHLORPYRIFOS Explanation Chlorpyrifos was evaluated in 1972, 1975 and 1977*; an acceptable daily intake (ADI) of 0.001 mg/kg bw was estimated and recommendations made for maximum residue levels (MRLs) in a range of commodities. This addendum contains data on residues following the application of chlorpyrifos to kiwi-fruit in trials in New Zealand. RESIDUES IN FOOD USE PATTERN Kiwifruit (Actinidia chinensis) is a major fresh export crop from New Zealand to 23 importing countries. The main insect pests are lepidopterous leaf rollers (mainly Ctenopseustis obliquana) and greedy scale (Hemiberlesia rapax). Chlorpyrifos has given excellent control of these pests. The proposed pattern required up to nine applications per season, with a maximum of 37.5 a.i./100 l at 2 000 l per application). The normal rate will be 0.5 kg a.i. per hectare per application. The normal interval between last application and harvest would be 14 days, although a shorter interval of as little as three days may occasionally be necessary to meet quarantine requirements of importing countries. RESIDUES RESULTING FROM SUPERVISED TRIALS Results of residue studies in chlorpyrifos and its major metabolite, 3,5,6-trichloro-2-pyridinol in three locations over two seasons, 1977 and 1979, were available (Mercer 1979). Two formulations were used on kiwifruit, "Hayward", Lorsban 50W a 50% wettable powder and Lorsban 50EC a 50% emulsifiable concentrate. Applications were made with a hand gun at 1 700 KPa pressure delivering 4.62 litres of spray per minute simulating commercial airblast sprayers. Table 1 summarizes the residues found in the trials. Residues in Trial II were determined on the whole fruit. In Trials I and II, the whole fruit residues were calculated from separate determinations on skin and pulp. In Trial III, the maximum skin residue was 20.7 mg/kg at 1 day, which fell to 9.2 mg/kg after 21 days. The edible portion normally contains less than 0.1 mg/kg at all times. * See Annex II for FAO and WHO documentation. TABLE 1. Chlorpyrifos residues in kiwifruit (whole fruit) New Zealand, 1977, 1979. Days after Residues in chlorpyrifos (mg/kg) application Trial I 1 Trial II 2 Trial III 3 50 EC 50 W 50 W 50 EC 0 0.3 -- -- -- -- 1 0.1 0.8 0.8 1.0 1.5 2.2 2 0.1 0.9 0.7 0.8 0.8 1.0 2.2 4 0.1 1.0 1.0 0.5 0.6 0.5 1.6 1.6 7 0.1 0.7 0.8 0.8 0.5 1.2 1.4 14 0.04 0.7 0.4 0.3 1.9 1.0 21 0.04 0.4 0.6 0.4 0.5 0.7 1 A single treatment of 25 mg/100 l chlorpyrifos (as 50 g/100 Lorsban 50 W) applied 20 April 1977. 2 Four applications at 25 g/100 l (50 g/100 l Lorsban 50W or Lorsban 50 EC) at intervals of 0, 33, 37 and 6 days, with final treatment on 2 May 1979. 3 Nine applications of 25 g/100 l chlorpyrifos (50 g/100 l Lorsban 50 W or 50 EC) at intervals of 0, 14, 14, 21, 21, 21, 28, 4 and 14 days, with final treatment on 30 April 1979. SAMPLING AND ANALYSIS About 1 kg fruit (10 to 15 units) was picked from each replicate 1, 2, 4, 7, 14 and 21 days after final treatment and from untreated on day 1 (after final treatments). These samples were frozen at -10°C until analysed. The method of analysis converts chlorpyrifos into the pyrimidol and determines total pyrimidol (which includes a small amount of metabolite already present). The limit of detection was generally lower (0.005 to 0.05 mg/kg) in edible flesh than on skin or whole fruit (0.05 to 0.1 mg/kg); chlorpyrifos recoveries ranged from 94 to 100 percent (near values). EVALUATION APPRAISAL Chlorpyrifos is effective for the control of leaf roller and greedy scale, two important pests of kiwifruit in New Zealand. Residue data from three locations over two seasons have provided the basis for estimating a maximum residue level. Almost all the chlorpyrifos and its main metabolite are retained in the inedible skin, residues in the edible flesh being at or about the limit of detection of the analytical method. RECOMMENDATIONS OF RESIDUE LIMITS Since maximum residue limits are recommended for kiwifruit on a whole commodity basis, 2 mg/kg was proposed, based on a 4-day interval between last application and harvest. REFERENCES Mercer, C. Chlorpyrifos residues in kiwifruit. New Zealand data. 1979 (Unpublished)
See Also: Toxicological Abbreviations Chlorpyrifos (ICSC) Chlorpyrifos (WHO Pesticide Residues Series 2) Chlorpyrifos (WHO Pesticide Residues Series 5) Chlorpyrifos (Pesticide residues in food: 1977 evaluations) Chlorpyrifos (Pesticide residues in food: 1982 evaluations) Chlorpyrifos (Pesticide residues in food: 1983 evaluations) Chlorpyrifos (JMPR Evaluations 1999 Part II Toxicological)