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    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)