Toxic effects of bound malathion residues in rats

The level of bound malathion residues in treated wheat grain and its toxic effects on rats were investigated. Wheat grain was treated with [14C] malathion (specific activity: 2.76 MBq/mg) to determine the bioavailability of bound residues in rats. At the same time, grain was treated with nonlabeled malathion to test for possible toxic effects of bound residues in a subchronic (90 days) feeding study in rats at two dose levels, 10 and 100 ppm. It was observed that the level of malathion-bound residues amounted to 11.28% of the applied dose (for six months). Also, it was noted that the main route of [14C]-malathion excretion was through the urine. This signifies that grain-bound malathion was bioavailable. In subchronic test on rats bound malathion residues (both dose levels) induced effects to some extent in organ weight (spleen and adrenals), and blood ChE activity. In both, males and females, there was an increase in SGPT activity (lower dose), and in alkaline phosphatase in females (higher dose). Hematological data showed changes only in hemoglobin concentration in males (both dose levels).