MALATHION DISPOSITION IN DERMALLY AND ORALLY TREATED RATS AND ITS IMPACT ON THE BLOOD-SERUM ACETYLCHOLINE ESTERASE AND PROTEIN PROFILE

C-14-methoxy-malathion with either pure or 50% E.C. formulated malathi on were applied orally or dermally at one tenth of their LD50 to two b atches of male albino rats. More than 90% of C-14 was released with ur ine after 24 hours. The rest of C-14 was detected in the feces, blood, intestines, liver and kidney in a descending order. No significant C- 14 was detected in other organs. Comparing the oral pure and formulate d malathion treatments , there was no significant variation in the rat e of disposition or excretion of C-14-malathion. However, the dermal t reatment revealed that the C-14-formulated malathion was released fast er than the pure one in urine in the first 24 hours; while the C-14-pu re malathion showed relatively higher levels in the feces and blood in the first 24 hours. In a third batch of male albino rats , the effect of the same level of dermal treatment by either pure or 50% E.C. form ulated malathion on serum acetylcholine-esterase (A.Ch. E.) activity a nd serum protein profile was studied. The serum A.Ch. E. activity was found to be inhibited to 40% activity after 6 to 24 hours for both tre atments. However, after 96 hours the serum of the pure malathion treat ed rats showed full recovery of A.Ch. E. activity, while the formulate d malathion treated showed only 60 % activity. The SDS-PAGE analysis s howed a differentiation in the serum protein bands of the 48 hours exp osed rats to formulated malathion which was confirmed by the scanned g el profile. The FPLC integrated chromatograms proved an initiation of a new protein band accompanied with rearrangement of the albumin and p re-albumin bands. Thus it can be concluded that, the impact on the blo od serum protein profile and A.Ch. E. activity can be used as reliable criteria to detect acute toxicity of malathion and other choline-este rase inhibitors in exposed field workers. Further research is needed t o elucidate the specificity and sensitivity of such criteria as biomar kers for human exposure.