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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

    PHENTHOATE

    Explanation

         The compound was evaluated by the 1980 Joint Meeting*. Temporary
    maximum residue limits were recommended for citrus fruits, carcass
    meat of cattle, milk and eggs. Some additional data on supervised
    trials have been provided since then, which are summarized in this
    evaluation.

    RESIDUES IN FOOD

    USE PATTERN

         In addition to the uses reported in the previous evaluation, the
    registered uses of phenthoate in Italy and Japan on rice, vegetables
    and on some other crops were reported to this Meeting. The data are
    summarized in Table 1.

    RESIDUES RESULTING FROM SUPERVISED TRIALS

    Citrus fruit

         Orange, lemon and grapefruit trees were treated at a rate of
    3.36-10.1 kg a.i./ha, in dilute sprays or at low volume. The 
    phenthoate and its oxygen analogue were analysed separately in the
    rind and pulp. Phenthoate residues found in the rind of fruits are
    summarized in Table 2. No residue was detectable in the fruit pulp at
    any rate or time (<0.03 mg/kg). Phenthoate oxon was in the range of
    0.04-0.07 mg/kg in the rind of orange (Iwata 1979).

         Lemon trees were treated 3 to 5 times, at intervals of 5 days,
    and at rate of 3 kg a.i./ha, in Japan. Samples were taken 7, 14 and 21
    days after the last applications (Nissani 1981). Phenthoate residues
    were analysed only in the pulp using a method with the limit of
    determination of 0.002 mg/kg. Residues detected are summarized in
    Table 3.

         The residues for whole fruit basis can be calculated taking
    into account the weight ratio of rind and whole fruit, which were
    0.187  0.063 for orange, 0.23  0.32 for grapefruit and 0.3  0.085
    for lemon. The residues calculated for whole fruit basis support the
    previously recommended TMRL of 1 mg/kg.

              

    *  See Annex II for FAO and WHO documentation

        TABLE 1.  Registered uses of phenthoate, Italy and Japan
                                                                                               

                                                                      Application
                                                                                               
    Crop                     Pest                     No.               Dose        % a.i.
                                                                     (kg a.i./ha)   in spray
                                                                                               

    Cabbage                  Large white butterfly    1-2            0.3-0.5        0.05
    Cauliflower
    Chinese cabbage                                   up to 4        0.5            0.025-0.05
    Radish                   Common white
    Turnip                   Aphids
    Spinach                  Thrips
    Lettuce                  Diamondback moth
    Celery                   Tobacco cutworm
    Tomato                   Cabbage armyworm
    Green pepper             Cabbage sawfly
    Eggplant                 Striped flea beetle
    Curcurbits               Cabbage webworm
    Pumpkin                  28 spotted ladybird
                             beetle
    Green onion              Greenhouse whitefly
    Onion                    Lima bean pod borer
    Potato                   Soybean pod borer
    Dasheen                  Japanese butter bur
                             borer
    Sweet potato             Bindweed leaf miner
    Carrot                   Sweet potato leaf
                             worm
    Great burdock            European corn borer
    Soybean
    Kidney bean
    Azuki bean
    Garden pea
    Broad bean
    Sweet corn
    Kaki persimmon           Japanese wisteria
                             mealybug                 up to 4        1.5            0.05
                             Persimmon fruit
                             moth bugs
    Japanese
    chestnut                 Peach pyralid moth       up to 4        1.5            0.05
    Tea                      Smaller tea tortrix      1-2            2              0.05
                             Tea tussock moth
                             White peach scale
                                                                                               
            TABLE 2.  Residues resulting from supervised trials in citrus fruit
                                                                                                                                     

                                            Application                   Residues (mg/kg) at intervals (days) after application2
                                                                                                                                     
    Crop           Country      Year        Rate
                                       No.  (kg a.i./ha)  Formulation     3         10        19        34-39     59
                                                                                                                                     

    Orange         USA          1978    1       3.26         4 EC                   0.68      0.41      0.23

    rind           California           1       6.72         4 EC                   2.1       1.5       0.73

                                        1       6.721        4 EC                   4.5       2.4       1.6

                                1979    1       4.2          4 EC         2.9       2.3       1.5       0.58      0.23

                                                8.4          4 EC         4         3         2.1       0.85      0.35

                                                8.41         4 EC         6.3       4.2       3         1.4       0.38

    Lemon                       1978    1       4.2          4 EC                   1.5       0.9       0.47

    rind           California                   8.4          4 EC                   2.8       1.7       0.78

                                                8.41         4 EC                   3.8       3.3       2.2

                                1979    1       5.04         4 EC                   3.7       2.7       1.1

                                               10.1          4 EC                   7         4.5       1.9

                                               10.11         4 EC                  14        11         5.7
                                                                                                                                     

    TABLE 2.  (con't)
                                                                                                                                     

                                            Application                   Residues (mg/kg) at intervals (days) after application2
                                                                                                                                     
    Crop           Country      Year        Rate
                                       No.  (kg a.i./ha)  Formulation     3         10        19        34-39     59
                                                                                                                                     

    Grapefruit                  19782   1       3.36         4 EC                   0.94      0.77      0.48

    rind           California                   6.72         4 EC                   2.1       1.6       0.87

                                                6.721        4 EC                   3.9       2.5       1.4

                                1979    1       0.05%        4 EC                   0.9       0.5       0.31

                                                0.1%         4 EC                   1.8       0.77      0.59
                                                                                                                                     

    Notes:  1  Low volume application at 454 l/ha;  2  The fruits were washed prior to analysis in this study.
            TABLE 3.  Phenthoate residues in citrus pulp
                                                                                            

                             Application                  Residues (mg/kg) at intervals
                                                          (days) after application
                                                                                            
                      Rate
    No.            (kg a.i./ha)     Formulation           7               14             21
                                                                                            

    3                   3           50 EC               0.012           0.008          0.004

    3                   3           50 EC               0.018           0.005          0.008

    5                   3           50 EC               0.01            0.009          0.009

    5                   3           50 EC               0.015           0.006          0.004
                                                                                            
    
    Maize

         Supervised trials were carried out applying a 50 EC formulation
    of phenthoate 4 times, 14 days apart, at rates from 0.5 kg a.i./ha to
    4 kg a.i./ha (Nissan 1981). Samples were taken 7 and 14 days after the
    last application and the grains were anlaysed. None of the samples
    contained detectable residues (<0.004 mg/kg).

    Rice

         Paddy rice was treated with a 50 EC formulation of phenthoate at
    various times and rates (Nissan 1981). The husked rice and straw were
    analysed, and the results are summarized in Table 4.

    Other crops

         Lettuce, onion, radish, spinach, tea, tobacco and tomato were
    treated with phenthoate in supervised trials carried out in Japan
    (Nissan 1981). The details of treatments and the results are
    summarized in Table 5.

         Infusion of tea leaves obtained from supervised trials referred
    to in Table 5 (6 g leaves in 360 cm3 water at 100C for 5 minutes)
    did not give rise to residues above the limit of determination
    (0.04 mg/kg) in potable tea.

        TABLE 4.  Residues of phenthoate in paddy rice
                                                                                                                           

                            Application                             Residues (mg/kg) at intervals (days) after application
                                                                                                                           
    Crop           No     Rate (kg a.i./ha) and
                          intervals   (days)         Formulation    7            14          18-21      41           102
                                                                                                                           

    Rice, paddy    5        1.28      (7)            50 EC          0.035        0.028       0.03

    husked                                                          41           3.31        2.11

                   5        1.42      (7)            50 EC                      <0.04       <0.04
                                                                                 1.91        0.871

                   6        1.42      (7)            50 EC         <0.04
                                                                    2.061

                   1        0.5                      50 EC                                                          <0.005
                                                                                                                    <0.011

                   1        0.5                      50 EC                                                          <0.005
                                                                                                                    <0.011

                   2        0.5       (32)           50 EC                                   0.012
                                                                                             0.541

                   2        0.5       (32)           50 EC                      <0.005
                                                                                 0.241
                   1        0.5       (30)           50 EC                                              0.0052
                                                                                                        0.321
                                                                                                        0.281
                                                                                                                           

    1  In straw of rice;  2  Two sets of experiments.

    TABLE 5.  Residues resulting from supervised trials in Japan
                                                                                                                                  

                              Application                                Residues (mg/kg) at intervals (days) after application
                                                                                                                                  
    Crop           No.     Rate
                       (kg a.i./ha) and     Formulation
                       intervals (days)                         3-4      7          10        14       20-21      24        27-34
                                                                                                                                  

    Lettuce        2   1 (7 days            50 EC                        0.08                 0.08     0.02
                   4   apart)                                            0.06                 0.05     0.009
    Onion          2   0.75 (7 days         50 EC              <0.01
                       apart)
                       (14 days                                                              <0.01
                       apart)
                   4   0.75 (7 days         50 EC                                            <0.01
                       apart)
                   4   0.75 " "             50 EC              <0.01
                   7   0.75 " "             50 EC              <0.01
    Radish         2   0.8 " "              50 EC                       <0.005
                       0.8 " "              50 EC                        0.073
                       0.8 " "              50 EC                                                                          <0.0051
                       0.8 " "              50 EC                                                                          <0.0052

    Spinach        2   0.75 " "             50 EC                                             0.015
                       0.75 " "             50 EC                        0.005               <0.005
                       0.75 " "             50 EC                                             0.018
                       0.75 " "             50 EC                        0.006               <0.005

    Tea            2   1 " "                50 EC                                                      0.009
                   3   1 " "                50 EC                                                      0.047
                   2   1.5 " "              50 EC                                                      0.039
                   3   1.5 " "              50 EC                                                      0.044
                                                                                                                                  

    TABLE 5.  (con't)
                                                                                                                                  

                              Application                                Residues (mg/kg) at intervals (days) after application
                                                                                                                                  
    Crop           No.     Rate
                       (kg a.i./ha) and     Formulation
                       intervals (days)                         3-4      7          10        14       20-21      24        27-34
                                                                                                                                  

    Tomato         3   1 " "                50 EC               0.42     0.034               <0.005
                   6   1 " "                50 EC               0.23     0.055               <0.005

    Tobacco        2   0.8 (5 days)         50 EC                                   0.13               0.244
                   2   1.6                                                          0.023              0.014
                                                                                                                                  

    1  Two sets of experiments;
    2  Four sets of experiments;
    3  Cutters of tobacco;
    4  Tips of tobacco.
        FATE OF RESIDUES

         Unwashed lemons were stored in paper bags for 2 and 7 days at
    8C. Rind residues for unstored fruit were 1.9  0.2 mg/kg and
    residues after 2 and 7 days of storage were 1.5  0.1 mg/kg and
    1.1  0.1 mg/kg. Chopped lemon samples were frozen. Over a 5-week
    interval, no changes in residue levels occurred from frozen storage;
    also, phenthoate was stable in the acetone extract at 8C (Iwata
    1979).

    NATIONAL MAXIMUM RESIDUE LIMITS REPORTED TO THE MEETING

         Some additional maximum residue limits and pre-harvest intervals
    registered in Japan were reported to the Meeting.

                                                                                     

    Crop                                    Pre-harvest Intervals         MRL
                                            (days)                        (mg/kg)
                                                                                 

    Pumpkin                                          1                     0.1

    Cucurbits, eggplant,
    green pepper, tomato                             3                     0.1

    Azuki bean, broad bean, cabbage,
    carrot, cauliflower, dasheen,
    garden pea, great burdock                        7                     0.1

    Kidney bean, onion, potato,
    soybean, sweet potato

    Apple, celery, Chinese cabbage,
    lettuce, radish, spinach,
    sweet corn, turnip                              14                     0.1

    Tea                                             21                     0.1

    Kaki persimmon                                  30                     0.1

    Chestnut                                                               0.1
                                                                                 
    
    EVALUATION

    APPRAISAL

         Since the compound was evaluated by the 1980 Joint Meeting,
    additional data resulting from supervised trials have been made
    available.

         Residues resulting from the treatment of citrus fruits were
    always less than 0.02 mg/kg in the pulp of citrus fruit and the
    residues calculated on whole product basis were lower than 1 mg/kg.
    The recent results support the temporary maximum residue limit (TMRL)
    that was recommended by the 1980 JMPR.

         Residues in husked rice were below 0.05 mg/kg, while the straw
    contained up to 4 mg/kg phenthoate.

         Residues in other crops were also low and unlikely to exceed
    0.1 mg/kg in lettuce and radish; 0.05 mg/kg in tea; 0.02 mg/kg in
    spinach; 0.01 mg/kg in maize and onion. In tomatoes the residues were
    0.2-0.4 mg/kg at 3 days post-treatment, but declined rapidly to less
    than 0.005 mg/kg in 14 days. These data were considered insufficient
    to estimate maximum levels that could be used to propose MRLs. The
    residue in frozen citrus rind was stable over a 5-week period and also
    in the acetone extract at 8C.

    RECOMMENDATIONS OF RESIDUE LIMITS

         The meeting recommends the following additional temporary MRL,
    which refers to phenthoate alone.

    Commodity           Limit               PHI on which recommendation
                        (mg/kg)             is based (days)
                                                                        

    Rice, hulled          0.05                          7

    FURTHER WORK OR INFORMATION

    Desirable

         Further data arising from supervised trials on lettuce, maize,
    onion, tomato, radish, spinach and tea from more than one country.

    REFERENCES

    Iwata, Y., O'Neal, J.R., Barkley, J.H. and Gunther, F.A. Phenthoate
    1979       applied to California citrus trees: Worker environment
               research and residue levels on and in fruit. Department of
               Entology, University of California, Riverside, U.S.A.
               (Unpublished)

    Nissan Chemican Industries Ltd.  Residue analysis data on various
    1981       crops in Japan. (Unpublished)


    See Also:
       Toxicological Abbreviations
       Phenthoate (Pesticide residues in food: 1980 evaluations)
       Phenthoate (Pesticide residues in food: 1984 evaluations)