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    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)