PESTICIDE RESIDUES IN FOOD - 1984
Sponsored jointly by FAO and WHO
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
The CCPR, at its fourteenth Session, asked the JMPR to reconsider
the definition of the residue, currently "sum of malathion and its
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.
The oxygen analogue should be excluded from the residue
definition without changing the numerical values of the MRLs.
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: