PESTICIDE RESIDUES IN FOOD - 1979 Sponsored jointly by FAO and WHO EVALUATIONS 1979 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, 3-12 December 1979 PHOSMET Explanation Phosmet was reviewed in 1978 when a Temporary ADI and some MRLs were recorded. Negative results obtained in a rat study and in a primate teratology bioassay did not fully remove concerns previously raised with regard to a possible teratogenic potential of phosmet and the meeting therefore requested additional teratology studies. This monograph addendum considers the results of such additional studies together with new data on the occurrence of residues following the use of phosmet on Kiwi fruit in New Zealand. EVALUATION FOR ACCEPTABLE DAILY INTAKE Special Study on Teratogenicity Groups of Wistar rats (20 pregnant rats per group) were administered phosmet during gestation at dose levels of 0 or 30 mg/kg body weight on day 8 or day 12 of gestation. A different group of animals was administered at dose levels of 0, 0.06, 1.5 and 30 mg/kg/day every other day throughout pregnancy starting on day 1 and ending on day 17. All rats were sacrificed on day 20 of gestation and examined for early and late resorptions and live, dead and malformed pups. Examination of pups for somatic and skeletal anomalies did not show any effect as a result of administration of phosmet in either testing regime. Under the conditions of this bioassay, phosmet did not induce a teratogenic response in rats (Short, 1979). COMMENTS Phosmet was reviewed by the 1978 Joint Meeting (FAO/WHO, 1979) when it was requested that additional teratology data be submitted to resolve controversial results noted in one teratology bioassay. Additional teratology data were made available, reviewed and found to be negative. These data served to alleviate the concerns of the previous meeting and allowed this meeting to allocate an ADI. The ADI was based on no-effect levels in two mammalian species. TOXICOLOGICAL EVALUATION Level Causing No Significant Toxicological Effect in Animals Rat: 40 ppm in the diet equivalent, to 2 mg/kg body weight Dog: 75 ppm in the diet equivalent, to 1.9 mg/kg body weight Estimate of Acceptable Daily Intake for Man 0 - 0.02 mg/kg body weight USE PATTERN: Kiwi fruit Kiwi fruit is now the second largest horticultural product exported from New Zealand. The fruit is subject to attack by a number of pests and diseases and to meet phytosanitary requirements of importing countries, it is necessary to spray regularly. The insecticide is used five times throughout the growing season, mid December, January, February, March and early April using 2.53 kg/ha per application or a maximum of 12.65 kg/ha in any one season. Kiwi fruit are picked in May so that the time interval between the last spray and harvest is not less than 21 days. RESIDUES RESULTING FROM SUPERVISED TRIALS Official trials carried out over two seasons (1974-76) resulted in residue levels ranging up to 17 mg/kg with more than half being about 10 mg/kg (Table 1). Residues of phosmet are mainly in the skin, which is hairy, relatively unpalatable and is normally discarded. Table 1. Treatment Residue on whole rate No. of commodity kg a.i./ha applications mg/kg 1974/75 season 3.6 2 8 (duplicate samples) 3.6 7 17 (small fruit) 12 (large fruit) 2.4 7 8 1975/76 season* 1.7 6 5 variety Haywood 3.7 6 10 variety Abbott 1.6 7 7 3.8 7 12 * Single samples at 21 days after last application. EVIDENCE OF RESIDUES IN FOOD IN COMMERCE Monitoring carried out on commercial crops at harvest yielded the information given in Table 2. Table 2. No. of samples Residues mg/kg Year (separate growers) Mean range 1975 20 3.8 0.3 - 10 1977 28 4.8 0.0 - 23 1978 9 2.2 0.0 - 9 NATIONAL LIMITS REPORTED TO THE MEETING The meeting was informed that the following national limits have been established: Country mg/kg Australia 15 New Zealand 15 USA 25 APPRAISAL The status of residues resulting from the use of phosmet on kiwi fruit was reassessed in the light of data from New Zealand. The meeting recognized that the bulk of the residues are below 10 mg/kg and that substantially all of the residues are in the skin which is not consumed. However, some lots of kiwi fruit retain significantly higher residues and are not covered by the MRL of 10 mg/kg recommended in 1978. It was agreed that the MRL should be increased to 15 mg/kg. RECOMMENDATION The meeting recommended that the MRL be amended as follows: Commodity MRL Preharvest interval on which (mg/kg) recommendation is based Kiwi fruit 15 21 REFERENCE Short R. (1979) Unpublished Teratology Data from Mid-West Research Institute submitted to WHO by the U.S. Environmental Protection Agency.
See Also: Toxicological Abbreviations Phosmet (ICSC) Phosmet (JMPR Evaluations 2003 Part II Toxicological) Phosmet (Pesticide residues in food: 1976 evaluations) Phosmet (Pesticide residues in food: 1978 evaluations) Phosmet (Pesticide residues in food: 1981 evaluations) Phosmet (Pesticide residues in food: 1984 evaluations) Phosmet (Pesticide residues in food: 1994 evaluations Part II Toxicology)