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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



    THIABENDAZOLE

    Explanation

    At the 11th Session of the CCPR the view was expressed that the
    proposed MRL of 0.1 mg/kg for strawberries was too low.  Residue data
    from the use of thiabendazole on strawberries as well as for tomatoes,
    cucumbers and cherries were received from Denmark.  They are assessed
    in this addendum.

    USE PATTERN

                                                                
    Preharvest                      Rate, kg/ha
    (Denmark)     Commodity             or          Formulation
                                     percent
                                                                

                  Strawberry           0.6          40% Emul.
                  Tomato*              0.10%        40% Emul.
                                    (2 g/plant)
                  Cherries             0.8          40% Emul.
                  Cucumber*            0.10%        40% Emul.
                                                                
    (* Glasshouse use)

    RESIDUES RESULTING FROM SUPERVISED TRIALS

    Data received from Denmark are summarized in Table 1 (Voldum-Claussen,
    1979).

    Strawberries

    The 0.1 MRL for thiabendazole on strawberries was based on a fumigant
    treatment in greenhouses and a 3-4 day preharvest interval.  Treatment
    with 24 g thiabendazole per 100 m2.  Under these conditions the
    limited data indicated that an MRL of 0.1 mg/kg would not be exceeded.

    In Denmark no pre-harvest interval is required.  The data indicate
    that the outdoor spray treatment results in residues around 0.7 mg/kg
    at 1 day and that these residues do not dissipate significantly within
    7 days.

    Tomato

    The 0.1 mg/kg MRL for tomatoes was also based on greenhouse fumigation
    in the Netherlands although the rate was 12-18 g/100 m2.  The Denmark
    application is also an indoor treatment, but is with a spray treatment
    with a 0.10% emulsifiable formulation.  Again, the residue data in
    Table 1 indicate a residue of around 0.7 mg/kg at 1 day and again
    there is little dissipation within 7 days.  The residue at 1-7 days is
    around 2 mg/kg from three applications.



        Table 1.  Residues from trials with Thiabendazole in Denmark (1979)

                                                                                                                       
                   Applications of
    Crop           40% Emulsion                Residues in mg/kg at intervals after applicationa
                                                                                                                       
                   No.       rate
                             kg ai/ha            4 hrs         1 day          2 days          4 days         7 days
                                                                                                                       

    Strawberry     1         0.6                                0.68           0.76            0.74           0.60
                                                             (0.67-0.70)    (0.75-0.78)     (0.62-0.86)    (0.52-0.69)

    Tomatob        1         0.10%                              0.64           0.70            0.71           0.54
                             (0.2 g/plant)                   (0.58-0.69)    (0.69-0.70)     (0.58-0.85)    (0.51-0.56)

                   3         0.10%                              1.9            2.0             2.1            1.5
                             (0.2 g/plant)                   (1.6-2.3)      (1.9-2.1)       (1.7-2.4)      (1.4-1.7)

    Cherries       1         0.8                  5.3                                                         3.6
                                               (4.7-5.8)                                                   (2.9-4.2)

    Cucumberb      1         0.10%                              0.97           0.80            0.71           0.32
                                                             (0.80-1.1)     (0.55-1.0)      (0.47-0.96)    (0.30-0.35)
                                                                                                                       

    a.  Limit of determination 0.1 mg/kg

    b.  Glasshouse use
    


    Cherries

    No MRL has been proposed for cherries.  The data supplied by Denmark
    show residues near 6 mg/kg at four hours after the spray treatment
    which dissipates to only around 4 mg/kg at seven days.

    Cucumber

    No MRL has been proposed for thiabendazole on cucumbers.  The data in
    Table 1 show initial residues of 1 mg/kg one day after a spray
    application indoors.  Again the residue is slow to dissipate.

    FATE OF RESIDUES IN FOOD IN COMMERCE OR AT CONSUMPTION

    No additional information was received.

    METHODS OF RESIDUE ANALYSIS

    No new methods of analysis were received.  The analyses of Table 1
    were based on extraction with ethyl acetate in alkaline solution,
    clean-up by liquid-liquid partitioning and determination by
    spectrometry.  Limit of determination was 0.10 mg/kg.

    APPRAISAL

    Residue data on strawberries were received from Denmark to support the
    view that the current 0.1 mg/kg MRL is too low.  Data from trials with
    tomatoes, cherries and cucumbers were also received.  The data
    indicate that the current 0.1 mg/kg MRLs on strawberries and tomatoes
    which were based oil greenhouse fumigation in the Netherlands, are too
    low for the practices in Denmark where spray treatments with all
    emulsifiable formulation is used.

    There are currently no MRLs for thiabendazole on cherries and
    cucumbers and available data do not warrant their proposal at this
    time.

    RECOMMENDATIONS

    It is recommended that previously recommended limits for strawberries
    and tomatoes be amended as follows:

                                                   
           Commodity                 Limit

         Strawberries                  1
          Tomatoes                     2
                                                   

    FURTHER WORK OR INFORMATION

    Desirable

    1.  Additional residue data and information on use patterns of
        thiabendazole on strawberries, tomatoes, cherries and cucumbers
        from countries other than Denmark and the Netherlands.

    2.  Information listed as desirable in the 1977 Evaluations.

    REFERENCES

    Voldum-Clausen, K. - Experiments on Pesticide Residues. No. S. 415,
    416, 419 and 420. (1979) Unpublished, Restricted, Ministry of the
    Environment, National Food Institute, Division of Pesticides and
    Contaminants, Morkhoj Bygade 19. DY-2860 Soborg, Denmark.
    


    See Also:
       Toxicological Abbreviations
       Thiabendazole (WHO Food Additives Series 39)
       Thiabendazole (AGP:1970/M/12/1)
       Thiabendazole (WHO Pesticide Residues Series 1)
       Thiabendazole (WHO Pesticide Residues Series 2)
       Thiabendazole (WHO Pesticide Residues Series 5)
       Thiabendazole (Pesticide residues in food: 1977 evaluations)
       Thiabendazole (Pesticide residues in food: 1981 evaluations)