An organophosphorous insecticide; metabolized into the cholinesterase inhibitors monothionotetraethyl pyrophosphate, dithionotetraethyl pyrophosphate, and triethylthionophosphate in vivo, which induce vomiting, fasciculation with muscular twitching, paralysis, and death (LD50 = 125 mg/kg) in rats; induces formation of capsular adhesion in the kidneys and ulcer formation in the duodenum of dogs; induces mucosal erosion and serosal seepage in the intestines of mini pigs