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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

    PERMETHRIN

    RESIDUES

    Explanation

         Permethrin was evaluated at the 1979, 1980, 1981 and 1982
    Meetings.1 Data now available for review include additional
    information on residues in Phaseolus beans and data which facilitate a
    first review of permethrin residues on peanuts and on sorghum fodder.

    RESIDUES IN FOOD AND THEIR EVALUATION

    RESIDUES RESULTING FROM SUPERVISED TRIALS

    Snap beans

         Permethrin is effective at rates of 0.11-0.22 kg a.i./ha against
    Spodoptera spp. and Heliothis spp. on beans. A preharvest withholding
    interval of three to seven days can generally be observed. On the
    basis of initial data available from trials in The Netherlands, United
    Kingdom and United States, the 1979 Meeting recommended an MRL of 0.5
    mg/kg for whole green beans.

         Additional data are now available from 11 trials which were
    conducted in the United States during 1979-81. In all cases permethrin
    was applied at 0.11 kg a.i./ha, by either ground or aerial means.
    Samples taken during the two weeks following the last of 4-10
    applications were analysed by gas chromatography with an electron
    capture detector (GC-EC), the method which was reviewed at the 1979
    Meeting. Results are shown in Table 1. During the first week after the
    last application, permethrin residue levels declined slowly and were
    in a range up to 0.61 mg/kg; two of 11 trials gave values at or above
    the existing MRL of 0.5 mg/kg. Residues after ground application were
    appreciably higher than after aerial applications (Pearson 1983).

    Sorghum

         In preharvest applications, permethrin was effective against
    sorghum midge, Contarinia sorghicola, at rates of 0.055-0.11 kg
    a.i./ha, and against fall armyworm, Laphygma frugiperda and chinch
    bugs, Blissus spp., at rates of 0.11-0.22 kg a.i./ha. A preharvest
    interval of 14 days was valid in sorghum grown for forage or of 28
    days in that grown for grain.

    __________

    1    See Annex 2 for FAO and WHO documentation.

         Residue data on grain sorghum were available from six trials,
    which were conducted in the United States in 1980-81, in which
    permethrin was applied by ground equipment at 0.22 kg a.i./ha. All but
    one of the samples of grain taken 27-31 days after application and
    analysed by GC-EC were shown to contain permethrin residues of 
    0.16-0.79 mg/kg, i.e. within the MRL of 2 mg/kg proposed by the 1980
    Meeting for postharvest uses of permethrin on cereal grains. One value
    of 4 mg/kg was recorded (Table 2) (Fitzpatrick & Pearson 1983).

         Samples of forage taken 14-15 days after application and analysed
    by GC-EC were shown to contain residues of 0.95-5.6 mg/kg, all values
    being corrected to 28.9 percent dry matter content (Table 2). When
    corrected to a dry weight basis, these figures were, with one
    exception, above or close to the corresponding levels found in stover
    left when grain was harvested 27 to 31 days after application. The
    exception, of 24 mg/kg in stover, coincided with the case in which
    grain residues were also high (see preceding paragraph) (Table 2)
    (Fitzpatrick & Pearson 1983).

    Peanuts

         Permethrin proved effective against velvetbean caterpillar,
    Anticarsia gemmatilis, and potato leafhopper, Empoasca fabae, at rates
    of 0.055-O.11 kg a.i./ha and against fall armyworm, Laphygma
    frugiperda, cutworms, Agrotis spp., rednecked peanutworm, Stegasta
    bosqueella and Heliothis spp., at rates of 0.11-0.22 kg a.i./ha. A
    preharvest interval of 14 days can usually be observed. Residue data
    on peanuts were available from five trials conducted in the United
    States during 1979-1980, in which permethrin was applied by ground
    equipment at 0.22 kg a.i./ha. Samples of peanuts taken 12-15 days
    after application and analysed by GC-EC contained permethrin levels of
    0.02-0.1 mg/kg (Table 3). Corresponding levels in the foliage were 
    3-11 mg/kg (Fitzpatrick 1982).

    APPRAISAL

         Additional data on residues enabled the Meeting to estimate
    maximum residue levels for sorghum fodder and peanuts. It was
    considered that the level for peanuts should apply to the group of
    legume oilseeds. New residues data on phaseolus beans indicated that
    the existing MRL of 0.5 mg/kg could be exceeded in good agricultural
    practice and the Meeting estimated an increased maximum level of 
    1 mg/kg. The commodity description should be changed from beans (whole
    green) to beans (with pod). All three estimates were considered
    suitable for establishing MRLs.



        Table 1.  Permethrin Residues in Snap Beans Following Supervised Trials - United States

                                                                                                                            

    Trial Location    Rate of        Spray Volume    Number of      Method of      Interval Between     Permethrin
      And Year        Application    (l/ha)          Applications   Application    Last Application     Residue (mg/kg)2
                      (kg ai/ha)1                                                  And Sampling         (corrected for
                                                                                   (Days)               % recovery)
                                                                                                                            

    Florida              0.11           900              5            Ground              0                 0.61
    1979                                                                                  1                 0.49
                                                                                          3                 0.60
                                                                                          7                 0.61

                         0.11           900             10            Ground              0                 0.32
                                                                                          1                 0.39
                                                                                          3                 0.28
                                                                                          7                 0.45

    Florida              0.11            45              7            Aerial              3                 0.06
    1980

    South Carolina       0.11           450              4            Ground              3                 0.27
    1981

    Delaware             0.11            45              4            Aerial              3                 Trace
    1980

    New York State       0.11           350              4            Ground              0                 0.12
    1979                                                                                  1                 0.24
                                                                                          3                 0.26
                                                                                          7                 0.21

                         0.11            45              4            Aerial              0                 0.09
                                                                                          1                 0.09
                                                                                          3                 0.09
                                                                                                                            

    Table 1 (continued)

                                                                                                                            

    Trial Location    Rate of        Spray Volume    Number of      Method of      Interval Between     Permethrin
      And Year        Application    (l/ha)          Applications   Application    Last Application     Residue (mg/kg)2
                      (kg ai/ha)1                                                  And Sampling         (corrected for
                                                                                   (Days)               % recovery)
                                                                                                                            

    Minnesota            0.11           450              4            Ground              3                 0.10
    1980
                                         45              4            Aerial              3                 0.04

    Wisconsin            0.11           950              5            Ground              3                 0.22
    1980

    Oregon               0.11           330              4            Ground              0                 0.50
    1979                                                                                  1                 0.47
                                                                                          3                 0.54
                                                                                          7                 0.12
                                                                                         14                 0.07
                                                                                                                            

    1    A 24% E.C. formulation was used.
    2    Limit of determination : 0.01 mg/kg.

    Table 2   Permethrin Residues in Sorghum Grain and Fodder - United States
                                                                                                                                 

    Trial Location     Rate of          Spray Volume    Number of        Interval Between     Permethrin Residue (mg/kg)2
    and Year           Application1     (1/ha)          Applications     Last Application     (corrected for % recovery)
                       (kg ai/ha)                                        And Sampling
                                                                         (Days)               Grain      Stover3     Fodder4
                                                                                                                                 

    Georgia              0.22               135              2               29               0.76       4.1         -
    1980

    Georgia              0.22               540              2               14               -          -           4.8
    1980                                                                     28               -          9.2         -

    Florida              0.22               330              2               14               -          -           0.95
    1981                                                                     27               0.16       -           -

    Texas                0.22               280              2               15               -          -           2.3
    1981                                                                     29               0.71       3.7         -

    Maryland             0.22               360              2               14               -          -           2.4
    1981                                                                     31               0.79       7.8         -

    Missouri             0.22               190              2               15               -          -           5.6
    1981                                                                     30               4.0        24          -

    Missouri             0.22               190              2               15               -          -           2.2
    1981                                                                     30               0.62       8.8         -
                                                                                                                                 

    1    A 24% E.C. formulation was used.
    2    Limit of determination : 0.02 mg/kg,
    3    Stover values were corrected to 90.2% dry matter,
    4    Forage values were corrected to 28.9% dry matter.

    Table 3   Permethrin Residues in Peanuts - United States

                                                                                                                            

    Trial Location      Rate of           Spray Volume     Number of         Interval Between        Permethrin
    And Year            Application1      (1/ha)           Applications      Last Application        Residue (mg/kg)2
                        (kg ai/ha)                                           And Sampling            (corrected for
                                                                             (Days)                  % recovery)
                                                                                                                            

    North Carolina      0.22              135              4                 14                      Trace
    1979

    Georgia             0.22              120              4                 14                      0.04
    1979

    Alabama             0.22              45               4                 14                      0.10
    1979

    Texas               0.22              325              5                 12                      0.04
    1980

    Florida             0.22              180-450          4                 15                      0.02
    1980
                                                                                                                            

    1    A 24% E.C. formulation was used.

    2    Limit of determination : 0.01 mg/kg.
    

    RECOMMENDATIONS

         The recommendations refer to permethrin (sum of isomers).
    Metabolites are not included.

         Commodity           MRL                   Remarks
                             (mg/kg)

         beans (with pod)    1              increased from 0.5 mg/kg for
                                            "beans, whole green"

         sorghum fodder      20             on a dry weight basis

         legume oilseeds     0.1

    REFERENCES - RESIDUES

    Fitzpatrick, R.D. Permethrin and permethrin metabolite residues on
    1982      peanuts and peanuts process fractions. ICI Americas Inc.,
              Agricultural Chemicals Division Report No. TMU0894/B.
              (Unpublished)

    Fitzpatrick, R.D. & Pearson, F.J. Permethrin residues on grain
    1983      sorghum. ICI Americas Inc., Agricultural Chemicals Division
              Report No. TMU0847/B (Revised) (Unpublished)

    Pearson, F.J. Permethrin and permethrin metabolite residues on
    1983      snapbeans. ICI Americas Inc., Agricultural Chemicals
              Division Report No. TMU0971/B. (Unpublished)



    See Also:
       Toxicological Abbreviations
       Permethrin (EHC 94, 1990)
       Permethrin (HSG 33, 1989)
       Permethrin (ICSC)
       PERMETHRIN (JECFA Evaluation)
       Permethrin (Pesticide residues in food: 1979 evaluations)
       Permethrin (Pesticide residues in food: 1980 evaluations)
       Permethrin (Pesticide residues in food: 1981 evaluations)
       Permethrin (Pesticide residues in food: 1982 evaluations)
       Permethrin (Pesticide residues in food: 1984 evaluations)
       Permethrin (Pesticide residues in food: 1987 evaluations Part II Toxicology)
       Permethrin (JMPR Evaluations 1999 Part II Toxicological)
       Permethrin (UKPID)
       Permethrin (IARC Summary & Evaluation, Volume 53, 1991)