Comparison of Acute Toxicity of Anticholinesterase Insecticides to Weanling and Adult Male Rats.

A comparison was made of the acute toxicity of a number of anticholinesterase insecticides in weanling and adult male rats. The results indicate that weanlings are about twice as susceptible as adults to parathion, methyl parathion, Systox, Di-Syston, Guthion, Malathion, Delnav, and Folex. A smaller increase in susceptibility of weanlings was noted with Ethion, Phosdrin, Dipterex and Sevin. Weanlings were about 5 times more susceptible to EPN and about 4 times more susceptible to Trithion than adult male rats. In the case of OMPA adults were about 5 times more susceptible than weanlings. The age differences in susceptibility are probably due to incomplete development of enzymes which catalyze the metabolism of anticholinesterase insecticides in the livers of young animals.