Comparative toxicity, anticholinesterase action and metabolism of methyl parathion and parathion in sunfish and mice

The in vitro metabolism of methyl parathion (O,O-dimethyl O-p-nitrophenyl phosphorothioate) and parathion (O,O-diethyl O,p-nitrophenyl phosphorothioate) and the sensitivities of the target cholinesterases to inhibition by their oxygen analogs were studied in sunfish (Lepomis gibbosus) and mice to determine the basis for the low toxicity of methyl parathion in sunfish (LD50 > 2500 mg/kg). The LD50 values of parathion and methyl parathion in mice...