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    PESTICIDE RESIDUES IN FOOD - 1980


    Sponsored jointly by FAO and WHO






    EVALUATIONS 1980





    Joint meeting of the
    FAO Panel of Experts on Pesticide Residues
    in Food and the Environment
    and the
    WHO Expert Group on Pesticide Residues
    Rome, 6-15 October 1980




    2,4-D

    Explanation

    At the 1978 Meeting of the Codex Committee on Pesticide Residues
    (CCPR) the United States of America, The Netherlands and Argentina
    considered the 0.2 mg/kg MRL for raw grain, recommended by the 1975
    Joint Meeting too low to accommodate the use of 2,4-D to control
    weeds shortly before harvest and proposed a 0.5 mg/kg MRL for raw
    grain (barley, oat, rye, wheat).  Other delegations favoured a
    lower MRL. Governments were asked to send data for consideration by
    the JMPR.  As no data were submitted to the JMPR the MRL was not
    changed and the proposal was advanced to Step 8 at 11th Session of
    CCPR in 1979.

    The residue data on which the MRL was based were reconsidered by
    the present Meeting, together with additional information from the
    U.S.A., especially on the occasional use of 2,4-D as a harvest aid
    (to control weeds and to facilitate machine harvesting) for small
    grain.

    RESIDUES IN FOOD

    RESIDUES RESULTING FROM SUPERVISED TRIALS

    Information contained in the 1975 Joint Meeting Evaluations
    (FAO/WHO, 1976) indicated that the occasional use of 2,4-D in small
    grain shortly before harvest can result in residues up to 0.4 mg/kg
    at recommended application rates of 1.5 kg/ha (or below) and
    pre-harvest intervals of at least 14 days.

    Further data resulting from supervised trials carried out before
    1975 and provided by the U.S.A. (USDA, 1980) are given in Table 1.
    Residues range up to 0.36 mg/kg when good agricultural practice is
    followed.

    Table 1.  Residues of 2,4-D in Small Grain1

                                                                           
    Type and rate of         Pre-harvest              Residues of 2,4-D
    application (kg/ha)    interval (days)                 (mg/kg)
                                                                           
    Dimethylamine salt
                  1              7                 0.06      0.29
                  1             14                 0.15      0.31
                  2              7                           0.39
                  2             14                           0.50

    Iso-propyl ester
                  1              7                 0.14      0.22
                  1             14                 0.09      0.15
                  2              7                 0.21      0.49
                  2             14                 0.31      0.31

    Iso-octyl ester
                  1              7                 0.18      0.26      0.36
                  1             14                 0.23      0.23      0.35
                  2              7                 0.35      0.45
                  2             14                 0.63
                                                                           

    1 Barley, oats and wheat only.

    APPRAISAL

    Residues of 2,4-D in or on cereal grains were last considered by the
    1975 Joint Meeting and an MRL of 0.2 mg/kg in raw grain was
    recommended.  The residue data on which this MRL was based were
    reconsidered by the present Meeting together with additional
    information from the U.S.A., especially on the occasional use of 2,4-D
    as a harvest aid (to control weeds and to facilitate machine
    harvesting) for small grains.

    At recommended dosages up to 1.5 kg/ha and a pre-harvest interval of
    14 days, 2,4-D residues on barley, oats, rye or wheat range up to
    about 0.5 mg/kg grain.  The available residue data provided a basis
    for increasing the MRL for these cereals to 0.5 mg/kg.  The MRL of 0.2
    mg/kg was retained for other cereal grains.

    RECOMMENDATIONS

    The meeting concludes that the maximum residue levels listed below are
    suitable for establishing MRLs to replace the previously recommended
    MRL for raw grain.

                                     Pre-harvest intervals on
    Commodity        Level (mg/kg)   which levels are based

    Barley               0.5                14 days
    Oats                 0.5                14 days
    Rye                  0.5                14 days
    Wheat                0.5                14 days
    Other cereal
    grains               0.2


    REFERENCE

    USDA. Submission from the United States Department of Agriculture to
    FAO, 22 May, 1980. 

    


    See Also:
       Toxicological Abbreviations
       D, 2,4- (AGP:1970/M/12/1)
       D, 2,4- (WHO Pesticide Residues Series 1)
       D, 2,4- (WHO Pesticide Residues Series 4)
       D, 2,4- (WHO Pesticide Residues Series 5)