Interaction of hexachlorocyclohexane and malathion in male guinea pigs after repeated dermal application.

Repeated application of hexachlorocyclohexane (HCH; 50 and 100 mg/kg) and malathion (200 and 400 mg/kg) alone or in combination daily for 30 days on the skin of male guinea pigs caused mild to severe signs of toxicity and death of animals. The experimental animals exhibited tremor, dyspnea, salivation, convulsion, diarrhea and paralysis of the limbs. These were associated with significant biochemical and morphological changes in skin, liver, kidney and testes. The inhibition of acetylcholinesterase appeared highly significant in the combined treatment, but was not suggestive of any HCH and malathion potentiation. The highest level of HCH residue was seen in fatty tissue after low dose treatment. This was in contrast to the high level seen in liver after larger doses of HCH. This study suggests that HCH and malathion did not elicit any potentiation effects in the parameters monitored and at the doses tested.