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    DIMETHOATE       JMPR 1977

    Explanation

    Dimethoate was evaluated by the Joint Meetings held in 1965 and 1966;
    a complete revision was written in 1967, with an addendum in 1970
    (FAO/WHO 1965, 1967, 1968, 1971). On the latter occasion, maximum
    residue limits were recommended for residues of dimethoate in tree
    fruits (2 mg/kg), tomatoes and peppers (1 mg/kg) and other vegetables
    (2 mg/kg), the residues to be determined as dimethoate and omethoate
    and expressed as dimethoate. (These levels had been recommended as
    temporary limits in 1967.) At the 1973 Joint Meeting (FAO/ESTO 1974b),
    the related compound formothion was reviewed and, as a result, maximum
    residue limits for dimethoate were recommended for blackcurrants (2
    mg/kg) and strawberries (2 mg/kg) to include residues resulting from
    the use of either formothion or dimethoate on those crops.

    Information received (Canada, 1976) has indicated that a maximum
    residue limit of 0.3 mg/kg is inadequate to cover residues arising
    from the use of dimethoate itself on strawberries at recommended
    application rates (up to 1.3 kg a.i./ha) with a pre-harvest interval
    of 7 days. The data summarized in Table 1 fully support this
    contention.

    RECOMMENDATION

    The previous recommendation of 0.3 mg/kg on strawberries is amended as
    follows. The limit is for the sum of dimethoate and omethoate
    expressed as dimethoate.

              Commodity      Limit, mg/kg

              Strawberries              1

    REFERENCES

    Canada (1976) Data provided by Canadian Government sources.
    (unpublished). 

    FAO/WHO (1965) Evaluation of the toxicity of pesticide residues in
    food. FAO Meeting Report, No. PL:1965/10/1; WHO/Food Add./27.65.

    FAO/WHO (1976) Evaluation of some pesticide residues in food.
    FAO:PL/CP/15; WHO/Food Add./67.32.

    FAO/WHO (1968) 1976 evaluation of someyestioide residues in food.
    FAO/PL:1967/M/11/1; WHO Food Add./68.30.

    FAO/WHO (1971) 1970 evaluations of some pestioide residues in food.
    AGP:1970/M/12/1; WHO Food Add./71.42.

        TABLE 1. Residues of dimethoate and omethoate on strawberries treated in supervised trials.

                                                                                                           
                          Applications

    Location            Rate                           Pre-harvest              Residues found (mg/kg)
                    (kg/a.i./ha)            No.      interval(days)    Dimethoate      Omethoate    Total
                                                                                                           
    California           1.1                 3              0             1.08           0.06       1.14
                                                            3             0.89           0.05       0.94
                                                            7             0.58           0.03       0.61
                                                           13             0.33           0.03       0.36

    Louisiana            1.1                 3              0             2.89           0.05       2.94
                                                            3             2.71           0.05       2.76
                                                            7             1.09           0.02       1.11
                                                           14             0.29           0.09       0.38

    Florida              1.1                 4              0             0.29           0.03       0.32
                                                            3             0.27           0.01       0.28
                                                            8             0.01           0.01       0.02
                                                           14             0.06           0.02       0.08

    N. Carolina         0.56                 3             14             0.02           0.01       0.03
                         1.1                 1             14             0.07           0.05       0.12
                      2 x 0.56 )                            0             1.26           0.05       1.31
                     + 1 X 1.1 )             3              3             0.86           0.10       0.96
                                                            7             0.34           0.10       0.44
                                                           14             0.01           0.00       0.01
                      2 x 1.1 )                             0             2.37           0.09       2.46
                      1 x 2.2 )              3              3             1.49           0.16       1.65
                                                            7             0.83           0.17       1.00
                                                           14             0.09           0.06       0.15

    New Jersey          0.56                 4              0             0.47           0.00       0.47
                                                            7             0.16           0.00       0.16
                                                           14             0.17           0.08       0.25
                                                                                                           
        


    See Also:
       Toxicological Abbreviations