CYHEXATIN JMPR 1974 Explanation The 1970 JMPR (FAO/WHO, 1971) recommended temporary tolerances of 2 mg/kg for cyhexatin (under the name of tricyclohexyltin hydroxide) on apples and pears. Inorganic tin and organotin degradation products are not included in the tolerance. The 1973 JMPR recommended additional tolerances of 2 mg/kg in citrus and manufactured tea, and practical residue limits of 0.2 mg/kg in meat and 0.05 mg/kg in milk fat. The 1974 Meeting of the Codex Committee on Pesticide Residues (CCPR) referred to the Joint Meeting a question as to whether the proposed limit of 2 mg/kg in fruits was too high and requested from the Joint Meeting a proposal for tolerances on cucumbers, gherkins, tomatoes, melons and bell peppers on the basis of data requested from governments. RESIDUES IN FOOD AND THEIR EVALUATION RESIDUES RESULTING FROM SUPERVISED TRIALS 1. Apples and pears Some new data from the Netherlands on apples suggest that residues in apples resulting from approved use patterns in that country would probably not exceed the national tolerance of 1 mg/kg. The use pattern in the Netherlands is 0.4-0.5 kg a.i./ha wettable powder sprays with a 28 day pre-harvest interval (PHI). Data available to the 1970 JMPR however showed that dosages of 0.42 - 1.68 kg a.i./ha are approved in other countries, with pre-harvest intervals as short as 2 days. A re-examination of the data on which the 1970 JMPR recommendations were based shows that a 2 mg/kg maximum limit is required for the residues likely to result from the uses practiced in countries other than the Netherlands. 2. Gherkins The only country responding to the request for data was the Netherlands. Treatments of gherkins in that country are principally limited to glasshouse culture. The residue data submitted are adequate to show that residues in glasshouse gherkins would not exceed 1 mg/kg, the national tolerance. 3. Cucumbers, melons, bell peppers, tomatoes Again, the only country responding to the request for data was the Netherlands, with the exception of two residue trials on tomatoes from the Republic of South Africa. All uses on these commodities in the Netherlands are under glass. The use pattern is 0.25 to 0.4 kg a.i./ha with a 3 day PHI. The data on cucumbers, tomatoes, and bell peppers indicate that residues under glasshouse conditions would not exceed 0.5 mg/kg, the national tolerance. No data were made available on melons but the Meeting concluded that residue data on cucumbers could be translated to melons of the muskmelon or cantaloupe variety. All of the data from the Netherlands is expressed as cyhexatin and based on measurements of total tin. The residue values are therefore somewhat larger than those which would be obtained by methods which determine only organotin. The Republic of South Africa submitted information that there is a national tolerance of 2 mg/kg for cyhexatin on tomatoes in conjunction with a registered use pattern of 0.7 kg a.i./ha with a 3 day PHI (outdoor use). The residue data show that a 2 mg/kg tolerance would be required to cover residues resulting from outdoor use under South African conditions. The South African data did not indicate the specific residues covered by the tolerance nor those determined by the analytical method employed in the study. APPRAISAL The 1974 CCPR has referred to the Joint Meeting a question regarding the need for the previously recommended 2 mg/kg tolerance for cyhexatin on apples and pears and a request for proposals from the Joint Meeting for tolerance on cucumbers, gherkins, tomatoes, melons and bell peppers on the basis of data requested from governments. Response to the request for information was obtained only from the Netherlands and the Republic of South Africa, the latter referring only to two trials on tomatoes. The Joint Meeting concluded that the previously recommended 2 mg/kg tolerances on apples and pears could not be reduced because use patterns currently registered in countries other than the Netherlands show a need for that level. The Netherlands proposal for tolerances on cucumbers, gherkins, bell peppers, melons, and tomatoes is based on glasshouse uses only. Residue data submitted by the Netherlands support a tolerance of 1 mg/kg on gherkins and 0.5 mg/kg on cucumbers, melons, bell peppers and tomatoes for the glasshouse uses. The 1973 JMPR considered a similar proposal from the Netherlands but could not recommend tolerances at that time because of inadequate residue data and inadequate information on outdoor uses on the same crops in other countries. Tolerances are not usually recommended to cover only a highly specialized use in one country when there is reason to believe that other agricultural uses are practiced in other countries. However, the response to the request to other governments for information on cyhexatin uses from the 1974 CCPR would indicate that there is no great interest in such uses other than on tomatoes in the Republic of South Africa. The Joint Meeting therefore concluded that a recommendation for tolerances on the subject crops (other than tomatoes) could be made with the limitation that the tolerances are intended to cover glasshouse uses only. The data from South African outdoor use on tomatoes would justify a tolerance of 2 mg/kg on that crop, that level being also adequate to cover glasshouse uses. RECOMMENDATIONS The following maximum residue limits are for cyhexatin excluding organic degradation products and inorganic tin. TOLERANCES mg/kg Apples, pears, citrus, tomatoes, tea (manufactured) 2 Gherkins 1 Cucumbers, melons, bell peppers (Glasshouse use only) 0.5 PRACTICAL RESIDUE LIMITS Meat 0.2* Milk and milk products (fat basis) 0.05* *Level at or about the limit of determination REFERENCES FAO/WHO (1971). 1970 Evaluations of some pesticide residues in food. AGP/1970/M/12/1; WHO/Food Add./71.42.
See Also: Toxicological Abbreviations Cyhexatin (WHO Pesticide Residues Series 5) Cyhexatin (Pesticide residues in food: 1978 evaluations) Cyhexatin (Pesticide residues in food: 1980 evaluations) Cyhexatin (Pesticide residues in food: 1981 evaluations) Cyhexatin (Pesticide residues in food: 1983 evaluations) Cyhexatin (Pesticide residues in food: 1989 evaluations Part II Toxicology) Cyhexatin (Pesticide residues in food: 1991 evaluations Part II Toxicology) Cyhexatin (JMPR Evaluations 2005 Part II Toxicological)