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    AGP:1970/M/12/1

    WHO/FOOD ADD/71.42

    1970 EVALUATIONS OF SOME PESTICIDE RESIDUES IN FOOD

    THE MONOGRAPHS

    Issued jointly by FAO and WHO

    The content of this document is the result of the deliberations of the
    Joint Meeting of the FAO Working Party of Experts and the WHO Expert
    Group on Pesticide Residues, which met in Rome, 9-16 November, 1970.

    FOOD AND AGRICULTURE ORGANIZATION OF THE UNITED NATIONS

    WORLD HEALTH ORGANIZATION

    Rome, 1971

    MALATHION

    Explanation

    This pesticide was evaluated by the 1966 Joint Meeting (FAO/WHO, 1967)
    which established the acceptable daily intake for man. Modifications
    in the recommended tolerances were made by the 1967 Joint Meeting
    (FAO/WHO, 1968), the 1968 Joint Meeting (FAO/WHO, 1969) and the 1969
    Joint Meeting (FAO/WHO, 1970).

    In the Report of the 1969 Joint Meeting, the following information was
    "Required before 30 June 1970":

    1. Residues in fruit and vegetables following uses in accordance with
       good agricultural practice in different countries.

    2. The minimum periods likely to pass between application and/or
       harvesting and the time the tolerance is to be applied in different
       countries.

    RESIDUES IN FOOD AND THEIR EVALUATION

    RESIDUES RESULTING FROM SUPERVISED TRIALS AND IN FOOD, IN
    COMMERCE OR AT CONSUMPTION

    In strictly supervised trials by the Agricultural Research service of
    the United states Department of Agriculture vegetables and fruits were
    treated at the maximum recommended rates, with the 57% E.C.
    formulation, and duplicate samples taken for analysis on the day the
    last application was made, and also after the recommended U.S.A.
    harvest interval. Samples were analysed by GLC for malathion and
    malaoxon using a flame photometric detector with a 560 nm filter;
    those taken at zero day were analysed both in the raw state and after
    washing in cold running water, and after washing and cooking according
    to 'home practice'. No malaoxon was detected in any sample; the
    results for malathion are given in Table I.

    Although the studies carried out in the U.S.A. by the National Canners
    Association (Farrow et al., 1968) agree that washing by 'home
    procedure' removes very little malathion from tomatoes, commercial
    washing procedures were shown to remove 84 to 95 percent of the
    residue. Canned tomatoes or tomato juice contained less than 1 percent
    of the malathion present in the original samples, whether processing
    was by commercial or 'home' methods. In a parallel study on
    field-sprayed green beans (Elkins et al., 1968), only a trace (< 0.05
    ppm) was found, regardless of the method of conservation.

    In a 12-month study based on 66 samples of food in total diets in
    England and Wales, Abbott et al., (1970) found malathion more often
    than any other organophosphorus compound. Even so, it was confined to
    three of the seven groups within the dietetic range, being found
    twelve times in cereal samples (0.01 to 0.04 ppm, mean 0.02 ppm),


        TABLE I

    Malathion residue study (K.R. Hill et al., 1970)
                                                                                                         

    Crop         No. of          Rate       Sampling                                        Harvest day
                 applic.     (kg a.i./ha)   intervals        Zero day samples (ppm)         samples (raw)
                                            (days)       Raw         Washed      Washed &       (ppm)
                                                                                 cooked
                                                                                                         

    Lettuce      Weekly
                 (5 weeks)

    " leafy                     2.25          14         25.5         10           6.6         0.0
                                                         25.5         14           6.6         0.0

    " head                      2.25           7         27            7.5         3.8         0.19
                                                         28           10.5         3.8         0.18

    Spinach      Weekly         2.25           7          6.5          3.9         1.6         0.14
                 (5 weeks)                                6.7          3.2         2.2         0.13

    Cabbage      Weekly         2.82           7          5.5          1.8         1.7         0.94
                 (5 weeks)                                4.6          2.0         1.5         0.81

    String       Weekly         2.25           1          0.8          0.4         0.3         0.48
    beans        (6 weeks)                                0.8          0.5         0.3         0.48

    Tomatoes     Weekly         2.25           1          0.35         0.35        0.05        0.3
                 (4 weeks)                                0.35         0.35        0.05        0.3

    Cherries     Twice          9.0            3          4.8          3.4         2.0         0.4
                                                          6.0          4.5         4.0         0.2

    Peaches      3 times       10.1            7      1.3(0.06)1/      0.25       (0.0)        0.04(0.0)
                                                      1.1(0.05)        0.22       (0.0)        0.04(0.0)
                                                                                                         

    1/ Figures in parentheses are for peeled fruit
    

    twice in green vegetables (0.01 and 0.03 ppm) and once in fruit and
    preserves (0.01 ppm).

    NATIONAL TOLERANCES

    The data in Table 1 indicate that no difficulty would be experienced
    in meeting even the German tolerances, indicated below, providing the
    harvest intervals are observed.

                                                            
                                                  ppm

    Crop                                    U.S.A.    German
                                                            

    Lettuce, spinach,
    cabbage, string beans                   8         3

    Tomatoes, cherries,
    peaches                                 8         0.5
                                                            

    APPRAISAL

    RECOMMENDATIONS FOR TOLERANCES

    Information from studies in the U.S.A. and from a compilation of
    commercial trials data indicates that the following revised tolerances
    can be recommended. These recommendations assume that the intervals
    specified between the last application and harvest have been observed:

                                                                       
    Crop              Interval between   Recommendation for tolerance
                      last application   (ppm)
                      and harvest
                      (days)
                                                                       
    Blackberries,
    raspberries       1                  8

    Grapes            3                  8

    Cherries          3                  6

    Peaches, plums    7                  6

    Apples            7                  2

    Strawberries      1                  1

    Blueberries       1                  0.5

    Pears             7                  0.5

                                                                       
    Crop              Interval between   Recommendation for tolerance
                      last application   (ppm)
                      and harvest
                      (days)
                                                                       

    Lettuce,
    endive,
    cabbage,
    spinach           7                  8

    Broccoli          3                  5

    Kale, turnips     7                  3

    Tomatoes          1                  3

    Beans (green)     1                  2

    Celery            7                  1

    Cauliflower,
    peas (in pod),
    peppers,
    eggplant          3                  0.5

    Roots
    (except
    turnips),
    Swisschard,
    collards,
    kohlrabi          7                  0.5
                                                                       

    The rate of breakdown of malathion is sufficiently fast to ensure that
    residues will decrease rapidly with time. They will also be
    substantially reduced by commercial washing procedures, for example
    85-95 percent tomatoes. Canned tomatoes have been shown to contain
    less than 1 percent of the residue present before canning. Washing,
    blanching and cooking of broccoli, kale, spinach and other green
    vegetables has been found to reduce the residue level by more than 90
    percent.

    This information is considered to meet the requirement set at the 1969
    Joint Meeting.

    REFERENCES

    Abbott, D.C., Crisp, S., Tarrant, K.R. and Tatton, J.O'G (1970)
    Pesticide residues in the total diet in England and Wales, 1966-1967.
    III.-Organophosphorus pesticide residues in the total diet. Pestic.
    Sci., 1: 10-13

    Elkins, E.R. Lamb, F.C., Farrow, R.P., Cook, R.W. Kawai, Margaret and
    Kimball, J.R. (1968) Removal of DDT, malathion, and carbaryl from
    green beans by commercial and home preparative procedures.
    J. agr. Fd Chem., 16: 962-966

    Farrow, R.P., Lamb, F.C., Cook, R.W., Kimball, J.R. and  Elkins,
    E.R.(1968)  Removal of DDT, malathion, and carbaryl from tomatoes by
    commercial and home preparative methods. J. agr. Fd Chem., 16: 65-71

    Hill, K.R. Report of residue analysis. PCB-70-6 (U.S. 1970 official
    report. Publication in preparation)
    


    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 (WHO Pesticide Residues Series 3)
       Malathion (WHO Pesticide Residues Series 5)
       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)