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THE INTERACTION OF AN ANTICHOLINESTERASE INSECTICIDE, DIAZINON, WITH A PYRETHROID INSECTICIDE, DELTAMETHRIN.
Citation:
Haines, W. T., M. M. Taylor, K M. Crofton, R S. Marshall, AND S. Padilla. THE INTERACTION OF AN ANTICHOLINESTERASE INSECTICIDE, DIAZINON, WITH A PYRETHROID INSECTICIDE, DELTAMETHRIN. Presented at 2001 NIEHS/NTA Biomedical Science and Career Fair, RTP, NC, May 4, 2001.
Description:
This present study explores the interaction of the toxicity induced by an organophosphorus insecticide, diazinon (diethyl 2-isopropyl-6methyl-4-pyrimidal phosphorothionate), with a pyrethroid insecticide, deltamethrin ((S)-a-cyano-3-phenoxybenzyl (1R,3R)-3-(2,2-dibromovinyl)-2,2-di-methylcyclopropanecarboxylate). Even though these two compounds have different mechanisms of toxicity (i.e., diazinon is a cholinesterase inhibitor, while deltamethrin causes prolonged Na+ channel depolarization), both insecticides are detoxified via carboxylesterases. The objective of the study was to determine if prior administration of diazinon (DIA) would accentuate the subsequent effects of deltamethrin (DLT). Adult, Long-Evans, male rats (n = 8/group) were orally dosed with either 1, 5, 20, 40, 80 mg/kg DIA (LD50>1200 mg/kg) or the corn oil vehicle, and 24 hours later orally dosed with 0 or 1 mg/kg DLT (LD50>128 mg/kg). Two hours after DLT (at the time of peak effect for DLT), acute toxicity was assessed by measuring motor activity in a figure-8 maze. Those animals pretreated with 20 mg/kg DIA and then treated with 1 mg/kg DLT showed approximately a 25% decrease in motor activity, whereas the animals that received only 1 mg/kg DLT showed no decrease in motor activity. This dose of DIA did not inhibit brain cholinesterase activity, either with or without DLT. These results suggest some dosages of DIA potentiate the neurotoxic effects of DLT. (This is an abstract of a proposed presentation and does not necessarily reflect EPA policy).