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    MALATHION       JMPR 1975

    Explanation

         Recommendations for maximum residue limits for malathion of 8
    mg/kg in cereals and 2 mg/kg in whole meal and flour from rye and
    wheat were made at previous Joint Meetings (FAO/WHO 1967, 1969). In
    1970, maximum residue limits were recommended for various fruits and
    vegetables (FAO/WHO, 1971). At the Eighth Session of the Codex
    Commission on Pesticide Residues (ALINORM 76/24 para. 144) it was
    pointed out that residues of malathion were highly persistent during
    long-term storage of grain at low temperature and low humidity and
    that milling of such grain resulted in residues in whole meal higher
    than the maximum residue limit of 2 mg/kg. In addition, it was
    indicated that new data from supervised trials on lettuce and apples
    would be submitted to the Joint Meeting. All governments were
    requested to provide residue data from supervised trials.

         Data and information on malathion residues in fruits and
    vegetables were made available to the Meeting.

    RESIDUES RESULTING FROM SUPERVISED TRIALS

         Data on malathion residues in apples and head lettuce from
    supervised trials in Canada were made available. The data summarized
    in Table 1 and 2, show the decline in malathion residues in both
    apples and lettuce with increasing pre-harvest intervals. The residue
    levels in lettuce were 40-80% lower than when the guard leaves were
    removed (Table 2).

         Malathion residues in apples from supervised trials in the United
    States of America (Yost, 1975) are shown in Table 3.

         Residues in pears ranged from 0.2-5.0 mg/kg (pre-harvest
    interval, 0 days) in seven trials in Washington, United States of
    America, following one application of malathion (25% WP or 57% EC) at
    rates of 0.57-1.9 kg/ha (Yost, 1975).

         Yost (1974) provided a summary of United States data on malathion
    residues in some crops (Table 3).

    RESIDUES IN FOOD IN COMMERCE OR AT CONSUMPTION

         During 1973-1974 a total of 307 food commodity samples in the
    Netherlands were analysed for malathion residues. Some of the data are
    summarized in Table 4. In addition to these data, a total of 38
    samples of swiss Chard, peas, beans, pears, red currants, raspberries,
    blackberries, parsley, radish, plums, carrots, grapes, cauliflower and
    chicory were analysed. Residues in 33 samples were below 0.01 mg/kg.
    Only five samples contained residues in the range 0.01-0.05 mg/kg.


    
    TABLE 1.  Malathion residues in apples (supervised trials - Canada)

                                                                                                                                      

                                                               Residues (mg/kg) at various locations1
                Rate of
                application      Pre-harvest
    Year        kg a.i/ha        Interval (days)         St Jean             Smithfield            Kentville           Summerland
                                                                                                                                      

    1973        1.25                  0              1.55 (1.28-2.00)     1.14 (1.00-1.41)

                                      1              0.88 (0.74-0.98)     0.61 (0.37-0.85)

                                      3              0.98 (0.86-1.18)     0.20 (0.16-0.23)

                                      5              0.95 (0.79-1.14)     0.13 (0.08-0.17)

                                      7              0.25 (0.22-0.30)     0.08 (0.04-0.10)

                                      14             0.15 (0.14-0.16)     0.06 (0.04-0.07)

                                      21             0.05 (0.04-0.06)     0.06 (0.06-0.07)

    19742       1.25                  3              0.52 (0.39-0.64)     0.11 (0.09-0.13)     1.57 (1.55-1.60)     1.82 (1.53-2.12)

                                      7              0.21 (0.15-0.26)     0.05 (0.04-0.05)     0.54 (0.49-0.59)     1.38 (1.18-1.59)

                                      14                                  0.03 (0.03-0.03)                          0.34 (0.29-0.38)
                                                                                                                                      

    1 In 1973 and 1974 samples were analysed in three and two laboratories, respectively. Averages and range of values determined
      (in parenthesis) are given.

    2 Rate of application for Smithfield trials was 5 kg/ha.

    TABLE  2.  Malathion residues in head lettuce (supervised trials - Canada)

                                                                                                                                      

                                                                Residues (mg/kg) at various locations1

               Rate of          Pre-harvest             With guard leaves                        Without guard leaves
               application      interval
    Year       kg a.i./ha       (days)           St Jean               Lethbridge             St Jean                Lethbridge
                                                                                                                                      

    1973       1.25             0                9.23 (6.45-11.5)      16.2 (13.3-18.8)       4.06 (3.73-4.25)       8.03 (7.57-8.74)
               (Lethbridge)

               2.0              1                4.60 (4.25-4.87)      3.35 (2.80-3.93)       0.90 (0.69-1.06)       1.58 (1.30-1.73)
               (St Jean)

                                3                0.71 (0.68-0.74)      1.36 (1.26-1.48)       0.16 (0.11-0.20)       0.53 (0.40-0.63)

                                5                0.05 (0.05-0.06)      0.35 (0.32-0.38)       0.03 (0.02-0.04)       0.16 (0.13-0.21)

                                7                0.06 (0.05-0.07)      0.32 (0.28-0.35)       0.01 (0.01-0.01)       0.06 (0.05-0.07)

                                14               0.02 (<0.01-0.03)    0.02 (0.01-0.03)       <0.01                  0.01 (<0.01-0.01)
                                                                                                                                      

    1 Samples were analysed in three laboratories. Averages and range of values determined (in parenthesis) are given.

    

        TABLE 3.  Malathion residues in apples from supervised trials

                                                                                             

         Rate of                                             Pre-harvest
         application                        No. of           interval
         (kg/ha)        Formulation     applications         (days)         Residues (mg/ha)*
                                                                                             

         0.5-1.15       25% WP or           1-4              0              1.4-21.1 (14)
                        57% EC                               1              0.4-3.3  (6)
                                                             2              1.0      (1)
                                                             3              0.4-2.3  (7)
                                                                                             

    * Figures in parenthesis are the number of samples.


    TABLE 4.  Summary of United States data on malathion residues in some crops

                                                                                             

                                            Recommended                 Residue at
                     Initial residue    pre-harvest interval     pre-harvest interval
         Crop            mg/kg              (days)                      mg/kg
                                                                                             

    Head lettuce         28-160                7                        1-10

    Endive               13-20                 7                        0.3-8

    Cabbage              14-45                 7                        trace - 8

    Spinach              10-167                7                        2.5-6

    Blackberries         2-10                  1                        2-7

    Raspberries          4-12                  1                        1-6

    Cherries             1.4-11.2              3                        2.1-5.9

    Peaches              2.2-18.8              7                        0.8-4.8

    Broccoli             26-106                3                        0.2-5
                                                                                             

    TABLE 5.  Survey data on malathion residues in the Netherlands, 1973-1974

                                                                                             

                                                    Number of samples

                                                    Residues (range mg/kg)

    Commodity                Total No.    <0.01    <0.01-0.05   <0.05-0.1    <0.1-1.0
                                                                                             

    Head lettuce                67          57           4             3            3

    Cucumbers                   38          36           2             -            -

    Tomatoes                    34          34           -             -            -

    Raw grain                   27          11           5             4            71

    Whole meal flour            12          6            3             1            2

    Celery                      22          22           -             -            -

    Apples                      21          15           4             2            -

    Bell peppers                16          16           -             -            -

    Endive                      11          7            2             2            -

    Strawberries                11          3            4             1            3

    Brussels sprouts            10          10           -             -            -
                                                                                             

    1 One sample of raw grain contained residues between 1 and 2 mg/kg.
        APPRAISAL

         The Codex Commission on Pesticide Residues referred to the Joint
    Meeting a request that the maximum residue limits for malathion in
    fruits and vegetables and the maximum residue limit of 2 mg/kg for
    whole meal and flour from rye and wheat be re-evaluated in the light
    of data provided by governments. No data were available to the Meeting
    on the residues in whole meal, flour and bread following milling of
    grain from long-term storage at low temperature and low humidity to
    re-evaluate the maximum residue limit of 2 mg/kg.

         Data from supervised trials on fruits and vegetables in Canada
    and the United States of America were available. The Canadian data for
    apples and head lettuce indicated that for Canadian conditions a
    maximum residue limit of 2 mg/kg with a pre-harvest interval of three


    days would be acceptable. However, the data from the United States
    trials support the maximum residue limits for apples and lettuce
    recommended at the 1970 Joint Meeting (FAO/WHO, 1971). Additional
    United States data on endive, cabbage, spinach, blackberries,
    raspberries, cherries, peaches and broccoli support the maximum
    residue limit recommendation of the 1970 Joint Meeting. The data for
    malathion residues on pears was for the day of application only (the
    pre-harvest interval in the United States of America is one day) and
    no recommendation could be made.

         The Joint Meeting concluded that in the light of the available
    information the recommendations made at the 1970 Joint Meeting for
    maximum residue limits for malathion should be maintained.

    FURTHER WORK OR INFORMATION

    DESIRABLE

    1.   Further information on residues in stored grains resulting from
    good storage practice including storage at relatively low temperature
    and humidity and the effect of milling, cooking and baking on these
    residues.

    2.   Residue data from supervised trials in countries where malathion
    is used.

    REFERENCES

    Yost, J. F. (1974) American Cyanamid Company, Princeton, United States
    of America. (Unpublished data)

    Yost, J. F. (1975) American Cyanamid Company, Princeton, United States
    of America. (Unpublished data)
    


    See Also:
       Toxicological Abbreviations
       Malathion (ICSC)
       Malathion (FAO Meeting Report PL/1965/10/1)
       Malathion (FAO/PL:CP/15)
       Malathion (FAO/PL:1967/M/11/1)
       Malathion (JMPR Evaluations 2003 Part II Toxicological)
       Malathion (FAO/PL:1968/M/9/1)
       Malathion (FAO/PL:1969/M/17/1)
       Malathion (AGP:1970/M/12/1)
       Malathion (WHO Pesticide Residues Series 3)
       Malathion (Pesticide residues in food: 1977 evaluations)
       Malathion (Pesticide residues in food: 1984 evaluations)
       Malathion (Pesticide residues in food: 1997 evaluations Part II Toxicological & Environmental)
       Malathion (IARC Summary & Evaluation, Volume 30, 1983)