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    PESTICIDE RESIDUES IN FOOD - 1983


    Sponsored jointly by FAO and WHO






    EVALUATIONS 1983





    Data and recommendations of the 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, 5 - 14 December 1983

    Food and Agriculture Organization of the United Nations
    Rome 1985

    PROPOXUR

    RESIDUES

    Explanation

         The Codex Committee on Pesticide Residues requested the Meeting
    to reconsider the definition of the residue. The original data
    submitted to the 1973 Meeting1 were studied and the relevant
    information is summarized in this re-evaluation.

    RESIDUES RESULTING FROM SUPERVISED TRIALS

         Propoxur disappears from the treated surface mainly by
    volatilization and only small amounts penetrate into the leaves. The
    surface residue is not, or is only slightly, affected by
    photodecomposition. Consequently, the major proportion of surface
    residue is the intact parent compound. The portion of the residue that
    penetrated into the plants was rapidly converted to water soluble
    metabolites, namely 2-hydroxyphenyl-N-methylcarbamate (metabolite A)
    and 2-isopropoxyphenyl-N-hydroxymethylcarbamate (metabolite B). The
    metabolites are conjugated with plant glucosides and are not
    extractable with organic solvents. In bean plants, the organosoluble
    residue consisted of the parent compound in the amounts of 58.7
    percent and 50.1 percent after three days and one day, respectively.

         The results of supervised trials on fruit and vegetables, listed
    in FAO/WHO 1973, were obtained by applying a method that measured the
    parent compound only.

         The residues in field crops were determined with a specific
    method and conjugated metabolites were released by enzyme hydrolysis
    before clean up. The original reports submitted for evaluation in 1973
    indicate the levels of the parent compound and metabolites A and B, as
    well as the total residue. The summary of these results is given in
    Table 1, as they are not included in FAO/WHO 1973.

    RECOMMENDATION

         The Meeting concluded that the metabolites can be excluded from
    the definition of the residue. The maximum residue limits (MRLs) refer
    to the parent compound alone. As a result of the new definition of the
    residue and reconsideration of experimental results, the limits for
    cereal grains - 0.5 mg/kg, fodders and straws - 5 mg/kg and legume
    animal feed (green) - 5 mg/kg must be changed. MRLs for fruit and
    vegetables remain the same.


              

    1  See Annex 2 for FAO and WHO documentation,

         The new limits are:

         cereal grains                 0.1 mg/kg
         fodders and straws            1 mg/kg
         legume animal feeds (green)   1 mg/kg

        Table 1   Propuxor residues resulting from supervised trials

                                                                                                 

    Crop              Dosage        Interval after   Residues (mg/kg)1
                      (mg a.i./ha)  treatment
                                    (days)           Parent           A          B          Total
                                                                                                 

    Pasture grass     0.28          0                <0.01-19.4 (8)
                                    0                11.8             <0.05      <0.02      11.82
                                    1                7.8              0.98       0.09       8.83
                                    3                4.5              2.3        0.19       6.99
                                    7                0.02             0.92       0.08       1.02

    Rangeland grass   0.28          0                29.8             <0.05      <0.03      29.80
                                    1                5.28             <0.05      0.09       5.37
                                    3                1.46             <0.05      0.03       1.49
                                    7                0.56             0.09       0.11       0.76
                      2 x 0.56      3                0.09             0.31       0.19       0.59
                                    7                0.53             0.47       0.2        1.2
                                    10               0.08             0.48       0.2        0.76

    Pasture grass     1.12          0                73.1             <0.05      0.03       73.13
                                    3                0.74             0.73       0.69       2.16
                                    7                0.22             0.57       0.7        1.49
                                    14               0.08             0.13       0.28       0.42
                                    21               0.05             0.15       0.12       0.32

    Cereal grain      0.56          30-95            <0.01-           0.05-      <.01-      <0.05-
     forage                                          0.79(7)          0.63 (7-)  0.37 (7-)  1.73
     oats             0.56 + 0.422  93-96            nd-0.02(5)       0.05(5)    <0.01
                                    14               <0.04            <0.05      0.09       0.09
                                    14               0.09             0.06       <0.01      0.15

    Alfalfa           1.12          3                10.75            1.22       0.19       12.26
                                                     1.43             0.53       0.21       2.17
                                                     1.7              0.2        0.16       2.06
                                    0                36.81            <0.05      <0.03      36.8
                                    3                2.83             0.45       0.12       3.4
                                    7                0.65             0.38       0.12       1.15

    Barley                          13               <0.04            <0.05      <0.02      <0.05
     straw                          14               0.24             <0.05      <0.01      0.24
     straw                                           0.32             <0.05      <0.01      0.32
    Rye                             14               <0.02            <0.01      <0.01
    Wheat                           14               <0.01            <0.05      <0.01      <0.05
     straw                                           0.21             <0.05      <0.01      0.21
                                                                                                

    1    The figures in brackets indicate the number of trials.
    2    0.56 mg a.i./400 kg seed + foliar treatment with 0.42 mg a.i./ha.



    See Also:
       Toxicological Abbreviations
       Propoxur (ICSC)
       Propoxur (WHO Pesticide Residues Series 3)
       Propoxur (Pesticide residues in food: 1981 evaluations)
       Propoxur (Pesticide residues in food: 1989 evaluations Part II Toxicology)