PESTICIDE RESIDUES IN FOOD - 1984


    Sponsored jointly by FAO and WHO






    EVALUATIONS 1984




    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
    Rome, 24 September - 3 October 1984

    Food and Agriculture Organization of the United Nations
    Rome 1985

    MALATHION

    Explanation

         The CCPR, at its fourteenth Session, asked the JMPR to reconsider
    the definition of the residue, currently "sum of malathion and its
    oxygen analogue".

    RESIDUES IN FOOD AND THEIR EVALUATION

         Many of the analyses for residues of malathion have been carried
    out by methods which do not differentiate between the parent compound
    and its oxygen analogue. The 1970 evaluation, however, reported the
    separate determination of the parent compound and its oxygen analogue
    in a number of fruits and vegetables. Measured residues of malathion
    were 0.06-25.5 mg/kg on the day of treatment and 0.04-0.94 mg/kg after
    recommended pre-harvest intervals of 3 or 7 days. No malaoxon was
    detected in any sample.

         No direct comparison of malathion and malaoxon residues in stored
    grains was available. However, experiments on the oxidation and
    hydrolysis of malathion by wheat grain esterases (Rowlands, 1964,
    1965) showed that the main products were non-toxic metabolites. A
    small proportion of oxon was formed, but it was rapidly degraded.

    RECOMMENDATION

         The oxygen analogue should be excluded from the residue
    definition without changing the numerical values of the MRLs.

    REFERENCES

    Rowlands, D.G. The degradation of malathion on stored maize and wheat
    1964      grains. J. Sci. Fd. Agric; 15: 824-829.

    Rowlands, D.G. The in vitro and in vivo oxidation and hydrolysis of
    1965      malathion by wheat grain esterases. J. Sci. Fd. Agric. 16:
              325-330.

    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 (WHO Pesticide Residues Series 5)
       Malathion (Pesticide residues in food: 1977 evaluations)
       Malathion (Pesticide residues in food: 1997 evaluations Part II Toxicological & Environmental)
       Malathion (IARC Summary & Evaluation, Volume 30, 1983)