FOLPET JMPR 1974 This monograph addendum should be read in conjunction with the monograph from the 1973 Meeting (FAO/WHO, 1974, p. 278-280). Explanation Arising out of the list of requirements published in the report of the 1969 Joint Meeting (FAO/WHO, 1970) some information on the degradation of folpet, methods of analysis, use patterns in several countries and residues resulting from supervised trials therein was referred to the FAO Working Party of Experts. RESIDUES IN FOOD AND THEIR EVALUATION USE PATTERN Data on the use pattern in countries other than the U.S.A. was required. Information was obtained on the current use patterns of folpet in several countries, which is summarized in Table 1. RESIDUES RESULTING FROM SUPERVISED TRIALS Residue data from supervised trials carried out in countries other than U.S.A. was required. New data was obtained from supervised trials on apples, peaches, grapes and strawberries (outdoor and glasshouse, Table 2). FATE OF RESIDUES The main degradation mechanisms of folpet are postulated to be the same as those for captan (FAO/WHO, 1970). Further information has been obtained since then. The IUPAC commission on Terminal Residues reviewed these data in its sixth Meeting in 1971. The dicarbonyl portion of captan forms imides, phthalamic acids and dicarboxylic acids (Lukens, 1966). The degradation pattern of the -SCCl3 moiety is more complex. A wide range of products containing sulphur in several oxidation states have been found (Lukens, 1966). It was shown that volatile products are formed such as COS (carbonyl sulfide) and CSCl2 (thiophosgene) (Somers, 1967; Lukens and Sisler, 1958b). The parent molecule on the CSCl2 moiety reacts with cysteine (Lukens and Sisler, 1958a), and/or with various thiols occurring in the plant (Richmond and Somers, 1966; Siegel, 1970). TABLE 1. Current use patterns of folpet in several countries Application rate Recommended pre-harvest Country Crops g/100l kg/ha intervals (days) Canada Apples 45-60 1 Blueberries, cherries 60 1.25 1 Black, red and white currants 120 1.5 7 Gooseberries 60 1 7 Cranberries 2.25 30 Strawberries 60 1 1 France Apples, pears 100 nil Grapes 100-175 15 Vegetables 100-125 Potatoes 150 nil Netherlands Apples, pears - Blackberries, raspberries, strawberries (outdoors) 125 4 Strawberries (glasshouse) 125 14 Red and black currants 125 10 Lettuce (glasshouse) 1.6 21 period March/ November 42 period November/ March South Africa Pome fruits, stone fruits, citrus fruits, potatoes, tomatoes 60 nil TABLE 2. Supervised trials with folpet in several crops (Part A: 0-10 days) Application Country Rate kg Pre-harvest interval in days Crop No a.i./ha Formulation 0-1 2-4 5-7 8-10 Netherlands3 Apples 1 2.0 w.p. 50% 1.48-1.60 1.41-1.57 1.39-1.47 1.07-1.47 Netherlands3 Red currants 5 2.251 w.p. 50% 17-4-33.6 9.0-33.6 8.1-13.2 5.1-16.3 Netherlands3 Raspberries 5 125g/100 l w.p. 50% 10.5-24.3 7.3-25.3 6.2-12.6 7.7-9.6 2 125g/100 l w.p. 50% 12.7-19.6 5.8-10.9 2.5-7.0 0.2- Netherlands3 Strawberries 5 125g/100 l w.p. 50% 0.6-1.1 0.8-1.7 (outdoor) 2 125g/100 l w.p. 50% 0.3-0.5 0.1-0.4 Netherlands3 Strawberries 1 2 w.p. 75% 1.8-3.1 (glasshouse) 2 2 w.p. 75% 1.8-2.8 1 1.5 x normal rate 2 After 49 days 3 Food Inspection service of the Netherlands (1965 and 1967). 4 Chevron Chemical Company (undated) TABLE 2. Supervised trials with folpet in several crops (Part B: 11-35 days) Application Country Rate kg Pre-harvest interval in days Crop No a.i./ha Formulation 11-14 16-21 22-28 29-35 Netherlands3 Red currants 5 2.251 w.p. 50% 1.8-8.1 n.d.-1.5 France4 Grapes 4 1.5 w.p. 50% n.d. (crushed) 4 1.5 w.p. 50% n.d. 4 1.65-1.75 w.p. 50% 2.1 8 0.9-2.1 w.p. 50% 0.31 4 1.2 w.p. 50%. 0.83 4 0.8-1.2 w.p. 50% n.d. Netherlands3 Lettuce 3 1.6 dust 8% 8.5-14.1 0.3-1.4 (glasshouse) 3 1.6 dust 8% 10-0-17.3 4.3-6.5 France4 Peaches 2 1.85 w.p. 50% n.d.-0.28 Netherlands3 Strawberries 5 125g/100 l w.p. 50% 0.1-0.3 (outdoor) 2 125g/100 l w.p. 50% 0.1-0.2 Netherlands3 Strawberries 1 2 w.p. 75% 1.2-1.3 1.8-2.2 (glasshouse) 2 2 w.p. 75% 1.6-2.4 2.0-3.0 3 2.1 w.p. 83% 7.8-12.6 0.5-5.62 3 2.1 w.p. 83% 4.2-10.6 1.6-5.0 1 1.5 x normal rate 2 After 49 days 3 Food inspection service of the Netherlands (1965 and 1967). 4 Chevron Chemical Company (undated). METHODS OF RESIDUE ANALYSIS Kilgore et al. (1967) developed a gas liquid chromatography method of analysis for folpet and captan. Since then the GLC method has been modified and improved (Pomerantz and Ross, 1968; Archer and Corbin, 1969). The limit of detection is about 0.01 mg/kg. The above mentioned methods are suitable or can be adapted for regulatory purposes. TLC methods are also available, but these are less sensitive (Engst and Schnaak, 1967). NATIONAL TOLERANCES Examples of national tolerances of folpet residues are reported in Table 3. TABLE 3. Examples of national tolerances reported to the Meeting Tolerance Country Commodities mg/kg Canada Celery 30 Apples, avocados, blackberries, blueberries, boysenberries, cherries, crab apple, cranberries, black, red and white currants, dewberries, gooseberries, grapes, huckleberries, leeks, lettuce, loganberries, onions, raspberries, strawberries, tomatoes 25 Citrus fruit, cucumbers, garlic, melons, pumpkins, squash 15 Belgium Fruit and vegetables 15 France Fruit and vegetables 15 Democratic Pome fruits (apples and pears), Republic of bananas, citrus fruit, black, red Germany and white currants, gooseberries, stone fruits, strawberries 5 Brassicas, fruits of vegetables, green beans, leafy vegetables, peas, potatoes 0.1 TABLE 3. (Cont'd.) Tolerance Country Commodities mg/kg Cereals, onions, meat, fat of meat, fish, milk, eggs, vegetable oils and fats 0 Federal Rep. Fruit and vegetables 15 of Germany Other agricultural crops 0.1 Hungary Fruit, including grapes, vegetables 15 Switzerland Fruit, including grapes 15 United States Celery, Cherries, leeks, lettuce, onions (green), shallots 50 Apples, avocados, blackberries, blueberries, boysenberries, crab apple, cranberries, red and white currants, dewberries, gooseberries, grapes, huckleberries, loganberries, raspberries, strawberries, tomatoes 25 Citrus fruit, cucumbers, garlic, melons, onions (dry bulb), pumpkins, summer squash, winter squash 15 Yugoslavia Fruit, vegetables, other agricultural crops 15 APPRAISAL In the light of present information about the nature and fate of terminal residues and the knowledge that the available analytical procedures are adequate for regulatory purposes the meeting agreed that the requirement for collaborative studies on analytical methods was no longer necessary. The Meeting was advised that results of further metabolism studies should be available in 1975. RECOMMENDATIONS TOLERANCES The tolerances recommended in 1969 have been confirmed as no longer necessary. The tolerance previously proposed for strawberries has been amended and additional tolerances are recommended. These are based on residues likely to be found at harvest following currently approved use patterns. Interval on which recommendations Crop ppm are based (days) Strawberries 20 14 Lettuce 15 14 FURTHER WORK OR INFORMATION DESIRABLE 1. Information on the nature, level and fate of residues following washing, blanching, storage and thermal processing of treated crops. 2. Residue data obtained by newer methods of analysis on the main commodities for which tolerances have been recommended. 3. Information on the fate of residues in soil. 4. Further data on the quantities of degradation products in relation to residues of the parent compound. 5. Results of metabolism studies currently planned. REFERENCES Archer, T.E., and Corbin, J.B. (1969) The site and fate of captan residues from dipping prunes prior to commercial dehydration. Food Technol. 23:235-238. Chevron Chemical Company. Data provided to Joint Meeting. Engst, R. and Schnaak, W. (1967) Dünnschichtchromatographische Bestimmung von Rückständen der Fungizide Captan und Phaltan. Nahrung, 11:95-100. FAO/WHO. (1970) 1969 Evaluations of some pesticide residues in food. FAO/PL/1969/M/17/1; WHO/Food Add./70/38. FAO/WHO. (1974) 1973 Evaluations of some pesticide residues in food. FAO/AGP/1973/M/9/1; WHO Pesticide Residues Series, No. 3. Food Inspection Service of the Netherlands, Amsterdam, (1965, 1967) Reports 47, 68, 76, 88, 101, 106 and 122. (Unpublished). IUPAC. (1971) Minutes of the sixth Meeting of the IUPAC Commission on Terminal Residues, Washington, D.C., July 1971. Kilgore, W.W., Winterlin, W. and White, R. (1967) Gas chromatographic determination of captan residues. J. agr. Food Chem., 15(6):1035-1037. Lukens, R.J. (1966) The fungitoxicity of compounds containing a trichloromethyl-thio-group. J. agr. Food Chem., 14(4):365-367. Lukens, R.J. and Sisler, H.D. (1958a) 2-Thiazolidinethione-4-carboxylic acid from the reaction of captan with cysteine. Science, 127:650. Lukens, R.J. and Sisler, H.D. (1958b) Chemical reactions involved in the fungitoxicity of captan. Phytopathology, 48:235-244. Pomerantz, I.H., Miller, L.J. and Kava, G. (1970) Extraction, cleanup, and gas-liquid chromatographic method for the analysis of captan, folpet and Difolatan in crops. J. Ass. off. Analyt. Chem., 53(1):154-157. Pomerantz, I.H., and Rose, R. (1968) Captan and structurally related compounds: thin layer and gas-liquid chromatography. J. Ass. off. analyt. Chem., 51(5):1058-1062. Richmond, D.V., and Somers, E. (1966) Studies on the fungitoxicity of captan. IV. Reactions of captan with cell thiols. Ann. Appl. Biol., 57:231-240. Siegel, M.R. (1970) Reactions of certain trichloromethyl sulfenyl fungicides with low molecular weight thiols. J. agr. Food Chem., 18(5):819-822, 823-826. Siegel, M.R., and Sisler, H.D. (1968) Fate of the phthalimide and trichloromethylthio (SCCl3) moieties of folpet in toxic action on cells of Saccharomyces pastorianus. Phytopathology, 58:1123-1128. Siegel, M.R. and Sisler, H.D. (1968) Reactions of folpet with purified enzymes, nucleic acids, and subcellular components of Saccharomyces pastorianus. Phytopathology, 58:1129-1133. Somers, E., Richmond, D.V. and Pickard, J.A. (1967) Carbonyl sulphide from the decomposition of captan. Nature, 215:214.
See Also: Toxicological Abbreviations Folpet (HSG 72, 1992) Folpet (ICSC) Folpet (FAO/PL:1969/M/17/1) Folpet (WHO Pesticide Residues Series 3) Folpet (Pesticide residues in food: 1984 evaluations) Folpet (Pesticide residues in food: 1986 evaluations Part II Toxicology) Folpet (Pesticide residues in food: 1990 evaluations Toxicology) Folpet (Pesticide residues in food: 1995 evaluations Part II Toxicological & Environmental)