MALATHION         JMPR 1973


         Malathion has been reviewed each year 1965/1971 (FAO/WHO 1965b,
    1967b, 1968b, 1969b, 1970b, 1971, 1972b). In the monographs of the
    1966 meeting (FAO/WHO 1967b) reference is made to the use of malathion
    for the treatment of dried beans as protection against damage by
    stored product pests. However, no recommendation appears to have been
    made for an appropriate residue limit.

         Many countries in tropical regions, especially in Asia and the
    Far East are heavily dependent upon dried beans (lentils, pulses) as a
    food staple, principle source of protein and valuable export
    commodity. In some areas the economy is largely dependent on the
    production and sale of dried beans (pulses). Export markets demand
    high quality standards and freedom from insect pests and their damage.

         Deterioration of quality in storage is entirely due to attack by
    pests. Damage is caused by a number of insect species which produce
    obvious holes in the beans. Unless the produce is fumigated regularly
    approximately 5% of the pulses are holed by insects during each month
    of storage. Too frequent fumigation causes tainting, loss of quality
    and excessive fumigant residues. The holes cause severe downgrading in
    the quality and price of the beans and greatly increase local costs
    because of the need for hand sorting.

         Lindane dusts and sprays are used in some areas but some species
    of pests have developed lindane resistant strains, To prevent
    infestation it is desirable to admit an acceptable insecticide.
    Malathion is the only product which could be considered at the present
    time. Malathion should also be applied to the outside of bags and
    stacks following fumigation.

         The addition of malathion in the form of dust or dilute emulsion
    spray is effective at rates of the order of 8 ppm on the weight of the
    beans. Extensive experience with malathion on wheat, oats, barley,
    rice and maize indicates that such treatment would remain effective
    for five to six months by which time the residue level would have
    declined to approximately 2-4 ppm.

         Extensive work (refer to the several JMPR monographs) indicates
    that malathion is readily removed from the surface of grain by washing
    and processing. It has been shown that simple cooking removes or
    destroys virtually all trace of malathion residues from cereal
    products, beans, peas and fruits. It may be assumed that a similar
    loss would occur from the normal cooking to which pulses are always


         That an additional tolerance be recommended as follows:

         Pulses (dried beans, lentils) 8 ppm


    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 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)