CHARACTERIZATION OF MALATHION RESIDUES IN DAIRY GOATS AND POULTRY

The chemical nature and magnitude of [C-14]malathion residues in the m ilk, eggs (whites and yolks), fat, liver, kidney, and muscle tissues i n dairy goats and laying hens were examined after repeated oral exposu re. The level and duration of the dose given to goats were equivalent to 86 ppm on feed for 5 days. Chickens received the equivalent of 28 p pm on feed for 4 days. Radioactive residues were characterized and ide ntified using solvent extraction and chromatography. The parent chemic al was not detectable, and immediate metabolites of malathion were not present in any tissues except traces of the mono- and dicarboxylic ac id metabolites observed in goat kidney. This observation was consisten t with urinary excretion as the major elimination pathway of malathion and immediate metabolites in poultry, laboratory animals, and humans. Extensive degradation and metabolism resulted in the reincorporation of the radiolabel into normal biogenic chemicals in all investigated s amples. The products were typical of those derived from the tricarboxy lic acid cycle. The products included pyruvate, lactate, lactose, olei c acid, stearic acid, and glycerol. Reincorporation of radiolabel into protein was also demonstrated by the isolation and hydrolysis of case in from milk. It was concluded that ingested malathion was converted t o acetate or other volatile fatty acids, metabolized to acetyl-CoA, an d then incorporated into the carbon pool.