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    PESTICIDE RESIDUES IN FOOD - 1981


    Sponsored jointly by FAO and WHO






    EVALUATIONS 1981







    Food and Agriculture Organization of the United Nations
    Rome

    FAO PLANT PRODUCTION AND PROTECTION PAPER 42

    pesticide residues in food:
    1981 evaluations

     the monographs

    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, 23 November-2 December 1981

    FOOD AND AGRICULTURE ORGANIZATION OF THE UNITED NATIONS
    Rome 1982

    CHLORPYRIFOS

    Explanation

         Chlorpyrifos was evaluated in 1972, 1975 and 1977*; an acceptable
    daily intake (ADI) of 0.001 mg/kg bw was estimated and recommendations
    made for maximum residue levels (MRLs) in a range of commodities. This
    addendum contains data on residues following the application of
    chlorpyrifos to kiwi-fruit in trials in New Zealand.

    RESIDUES IN FOOD

    USE PATTERN

         Kiwifruit  (Actinidia chinensis) is a major fresh export crop
    from New Zealand to 23 importing countries. The main insect pests are
    lepidopterous leaf rollers (mainly Ctenopseustis obliquana) and greedy
    scale  (Hemiberlesia rapax). Chlorpyrifos has given excellent control
    of these pests. The proposed pattern required up to nine applications
    per season, with a maximum of 37.5 a.i./100 l at 2 000 l per
    application). The normal rate will be 0.5 kg a.i. per hectare per
    application. The normal interval between last application and harvest
    would be 14 days, although a shorter interval of as little as three
    days may occasionally be necessary to meet quarantine requirements of
    importing countries.

    RESIDUES RESULTING FROM SUPERVISED TRIALS

         Results of residue studies in chlorpyrifos and its major
    metabolite, 3,5,6-trichloro-2-pyridinol in three locations over two
    seasons, 1977 and 1979, were available (Mercer 1979). Two formulations
    were used on kiwifruit, "Hayward", Lorsban 50W a 50% wettable powder
    and Lorsban 50EC a 50% emulsifiable concentrate. Applications were
    made with a hand gun at 1 700 KPa pressure delivering 4.62 litres of
    spray per minute simulating commercial airblast sprayers.

         Table 1 summarizes the residues found in the trials.

         Residues in Trial II were determined on the whole fruit. In
    Trials I and II, the whole fruit residues were calculated from
    separate determinations on skin and pulp. In Trial III, the maximum
    skin residue was 20.7 mg/kg at 1 day, which fell to 9.2 mg/kg after 21
    days. The edible portion normally contains less than 0.1 mg/kg at all
    times.

              

    *    See Annex II for FAO and WHO documentation.

        TABLE 1.  Chlorpyrifos residues in kiwifruit (whole fruit) New Zealand, 1977, 1979.
                                                                                               

    Days after                        Residues in chlorpyrifos (mg/kg)
                                                                                               
    application         Trial I 1              Trial II 2                     Trial III 3
                                       50 EC               50 W           50 W           50 EC
                                                                                               

    0                   0.3            --                  --             --             --
    1                   0.1            0.8 0.8             1.0            1.5            2.2
    2                   0.1            0.9 0.7 0.8         0.8            1.0            2.2
    4                   0.1            1.0 1.0 0.5 0.6     0.5            1.6            1.6
    7                   0.1            0.7 0.8 0.8         0.5            1.2            1.4
    14                  0.04           0.7 0.4             0.3            1.9            1.0
    21                  0.04           0.4 0.6             0.4            0.5            0.7
                                                                                               
    
    1  A single treatment of 25 mg/100 l chlorpyrifos (as 50 g/100
       Lorsban 50 W) applied 20 April 1977.

    2  Four applications at 25 g/100 l (50 g/100 l Lorsban 50W or
       Lorsban 50 EC) at intervals of 0, 33, 37 and 6 days, with final
       treatment on 2 May 1979.

    3  Nine applications of 25 g/100 l chlorpyrifos (50 g/100 l Lorsban
       50 W or 50 EC) at intervals of 0, 14, 14, 21, 21, 21, 28, 4 and
       14 days, with final treatment on 30 April 1979.

    SAMPLING AND ANALYSIS

         About 1 kg fruit (10 to 15 units) was picked from each replicate
    1, 2, 4, 7, 14 and 21 days after final treatment and from untreated on
    day 1 (after final treatments). These samples were frozen at -10C
    until analysed.

         The method of analysis converts chlorpyrifos into the pyrimidol
    and determines total pyrimidol (which includes a small amount of
    metabolite already present).

         The limit of detection was generally lower (0.005 to 0.05 mg/kg)
    in edible flesh than on skin or whole fruit (0.05 to 0.1 mg/kg);
    chlorpyrifos recoveries ranged from 94 to 100 percent (near values).

    EVALUATION

    APPRAISAL

         Chlorpyrifos is effective for the control of leaf roller and
    greedy scale, two important pests of kiwifruit in New Zealand.

         Residue data from three locations over two seasons have provided
    the basis for estimating a maximum residue level. Almost all the
    chlorpyrifos and its main metabolite are retained in the inedible
    skin, residues in the edible flesh being at or about the limit of
    detection of the analytical method.

    RECOMMENDATIONS OF RESIDUE LIMITS

         Since maximum residue limits are recommended for kiwifruit on a
    whole commodity basis, 2 mg/kg was proposed, based on a 4-day interval
    between last application and harvest.

    REFERENCES

    Mercer, C. Chlorpyrifos residues in kiwifruit. New Zealand data.
    1979      (Unpublished)


    See Also:
       Toxicological Abbreviations
       Chlorpyrifos (ICSC)
       Chlorpyrifos (PDS)
       Chlorpyrifos (WHO Pesticide Residues Series 2)
       Chlorpyrifos (WHO Pesticide Residues Series 5)
       Chlorpyrifos (Pesticide residues in food: 1977 evaluations)
       Chlorpyrifos (Pesticide residues in food: 1982 evaluations)
       Chlorpyrifos (Pesticide residues in food: 1983 evaluations)
       Chlorpyrifos (JMPR Evaluations 1999 Part II Toxicological)