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    CHLOROBENZILATE      JMPR 1975

    Explanation

         At the 8th Session of the Codex Committee on Pesticide Residues
    in 1975 a question was raised concerning the pre-harvest interval
    considered by the Joint Meeting when establishing its recommendations
    (Alinorm 76/24, para. 73). Chlorobenzilate was evaluated by the Joint
    Meeting in 1965, 1968 and 1972.

    Use pattern

         Chlorobenzilate is applied as a wettable powder or emulsifiable
    concentrate to apples and pears at rates ranging from 15 to 60 g/100 l
    with 1 to 4 applications per season. Normally, treatment is required
    in mid to late summer for the control of various mites, but depending
    upon seasonal conditions and the effectiveness of biological control
    agents it may be necessary to treat apple and pear crops within 7 to
    14 days of harvest.

    Residues found in supervised trials

         In addition to the information reported in the 1965, 1968 and
    1972 monographs further information has been published by Bartsch et
    al. (1971). A summary of the data on residues in apples, pears and
    walnuts is included in Table 1.

    APPRAISAL

         The data considered previously indicate that chlorobenzylate is
    retained almost entirely in the surface layer of fruit. The residue is
    stable to atmospheric and biological influences and, except an leaves
    which are growing fairly rapidly the residue levels decline only
    slowly with a half-life of more than 14 days.

         The evidence available indicates that the previously recommended
    maximum residue limit of 2 mg/kg for pears will cover the residues
    resulting from current uses when there is a pre-harvest interval of
    one week. However, in the case of apples it is likely that some
    residues will exceed 2 mg/kg for four and possibly six weeks after
    spraying.

         The treatment of apples two weeks before harvest is not usually
    required, but situations frequently occur where mite infestations will
    require treatment two weeks before harvest. For this reason the Joint
    Meeting in 1968 recommended a maximum residue limit of 5 mg/kg.


    
    TABLE 1.  Chlorobenzilate residues in various crops

                                                                                                                                               

                                    Dosage and
                                    formulationb                                         Interval
                                    (% or lb/100 US                                      between last              Residues
                                    gal or/acre) and                             No.     appl. and                 (ppm) and
    Crop and    Country             (g.a.i./100 l                                of      sampling       Anal.      plant parts
    variety     and year    Ref.a   or kg a.i./ha)      Application dates        appl.   (days)         methodc    analysed      
                                                                                                                                               

                                                                                                                   fruits

    Apples      USA         G.A.    1 lb of 25 WP       12.VI.                   1       0              UV         9.73
                N. Jersey           30 g.a.i./100 l
                (1952)              1 lb of 25 EC       12.VI.                   1       0              UV         16.99
                                    30 g.a.i./100 l
                                    1 lb of 25 WP       18.VII./25.VII.          2       7              UV         4.81
                                    30 g.a.i./100 l
                                    2 lb of 25 WP       18.VII./25.VII.          2       7              UV         7.92
                                    60 g.a.i./100 l
                                    1 lb of 25 EC       18.VII./25.VII.          2       7              UV         3.40
                                    30 g.a.i./100 l

    Apples      USA         G.A.    1 lb of 25 WP       14.VIII.                 1       33             UV         3.84          E. Bartsch
                N. York             30 g.a.i./100 l     14.VIII.                 1       33             UV         0.00          et al.
                (1953)              1/2 lb of 25 WP     15.VI./30.VI./15.VII./   5       56             UV         2.62
                                    15 g.a.i./100 l     30.VII./12.VIII.

    Apples      USA         G.A.    2 lb of 25 WP       29.VI./13.VII./1.VIII./  4       0              GC         4.0
    Red         Oregon              60 g.a.i./100 l     16.VIII.                         0                         4.0
    Delicious   (1967)                                                                   6                         5.3
                                                                                         6                         2.8
                                                                                         13                        4.8
                                                                                         13                        3.2
                                                                                         30                        1.9
                                                                                         30                        2.1
                                                                                         42                        1.8
                                                                                         42                        1.9

    TABLE 1.  (Cont'd.)
                                                                                                                                               
                                    Dosage and
                                    formulationb                                         Interval
                                    (% or lb/100 US                                      between last              Residues
                                    gal or/acre) and                             No.     appl. and                 (ppm) and
    Crop and    Country             (g.a.i./100 l                                of      sampling       Anal.      plant parts
    variety     and year    Ref.a   or kg a.i./ha)      Application dates        appl.   (days)         methodc    analysed      
                                                                                                                                               
    Pears       USA         G.A.    2 lb of 25 WP       21.VI./18.VII./19.VIII.  3       8              UV         0.53          Chlorobenzilate
                Calif.              60 g.a.i./100 l                                      8                         0.36          and
                (1953)                                                                   8                         0.51          chloropropylate
                            G.A.    2 lb of 25 WP       9.VI./4.VII.             2       60             UV         0.14
                                    60 g.a.i./100 l                                      60                        0.08
                                                                                         60                        0.11
                                                                                         60                        0.02

    Pears       USA         G.A.    1-1/2 lb of 25 WP   26.V./19.VI.             2       31             UV         0.37              "
    Bartlett    Calif.              45 g.a.i./100 l                                      31                        0.38
                (1953)                                                                   31                        0.42

                                                                                                               shell    meat

    Walnuts     USA         G.A.   1) 0.76 lb a.i. of   1) 19.VII.               2       28             GC     <0.1     <0.1         "
    Hartley     Calif.                4 E 0.85 kg
                                      a.i./ha
                (1966)             2) 2.25 lb a.i. of   2) 30.VIII.                      28                    <0.1     <0.1
                                      4 E 2.5 kg
                                      a.i./ha
                                      + surfactant      before husk split
                                      X-77 at 4         spray mixture:
                                      oz./100 gal       200 gal/acre

                            G.A.   1) 1.5 lb a.i. of    1) 19.VII.               2       28             GC     <0.1     <0.1
                                      4 E 1.68 kg
                                      a.i./ha
                                   2) 4.5 lb a.i. of    2) 30.VII.                       28                    <0.1     <0.1
                                      4 E 5.0 kg
                                      a.i./ha
                                      + surfactant      before husk split
                                      X-77 at 4 oz/100  spray mixture:
                                      gal               200 gal/acre
                                                                                                                                               
    a  References:  G.A. = Geigy Chemical Corp., Ardsley (N.Y.): Residue reports, unpublished.
    b  Formulation: WP = wettable powder, EC = emulsifiable concentrate, and E = emulsifiable concentrate.
    c  Analytical method: UV = ultraviolet, and GC = gas chromatographic.
    

         Apparently an error occurred in the preparation of the 1972
    Monograph because the maximum residue limit for apples and pears,
    carried forward from the previous monograph appears as "2 ppm" instead
    of "5 ppm". The data published in the monographs of the 1968 Meeting
    certainly support the need for a 5 mg/kg limit for apples whereas
    2 mg/kg is sufficient for pears.

         The new data demonstrate that when chlorobenzilate is applied to
    apples according to the good agricultural practice approved in several
    countries, the residues frequently exceed 2 mg/kg and can easily reach
    5 mg/kg but in the case of pears the 2 mg/kg limit is not likely to be
    exceeded. Accordingly the Meeting confirmed the 2 mg/kg limit for
    pears and recommended that the maximum residue limit established for
    apples in 1968 should be confirmed as 5 mg/kg.

    RECOMMENDATION

         The maximum residue limit for chlorobenzilate recommended in 1972
    is corrected to the recommendation made in 1968 and the new data
    considered by this Meeting as follows:

                                                                        

                                                Pre-harvest interval
                        Maximum residue         on which recommendations
         Commodity           limit              are based (days)
                                                                        

          Apples             5 mg/kg                   14 days
                                                                        

    REFERENCES

    Bartsch, E., Eberle, D., Ramsteiner, K., Tomann, A. and Spindler, M.
    (1971) The carbinole acarides: chlorobenzilate and chloropropylate. In
    Gunther, F. A, and Gunther, J. D., Eds. "Residue reviews", 39:1.
    


    See Also:
       Toxicological Abbreviations
       Chlorobenzilate (ICSC)
       Chlorobenzilate (FAO Meeting Report PL/1965/10/1)
       Chlorobenzilate (FAO/PL:1968/M/9/1)
       Chlorobenzilate (WHO Pesticide Residues Series 2)
       Chlorobenzilate (Pesticide residues in food: 1977 evaluations)
       Chlorobenzilate (Pesticide residues in food: 1980 evaluations)
       Chlorobenzilate (IARC Summary & Evaluation, Volume 5, 1974)
       Chlorobenzilate (IARC Summary & Evaluation, Volume 30, 1983)