Effects on acute organophosphorus poisoning in rats in aging and solubility of organophosphates.

Various organophosphorus compounds with low acute toxicity are predominantly used as insecticides worldwide. Human acute organophosphorous poisoning often occurs as a result of accidental, criminal or suicidal ingestion. We determined the effect of rat age and lipid solubility of organophosphates on acute organophosphorus poisoning.After trichlorfon with high water solubility was administered to rats, it and its metabolite, dichlorvos, rapidly disappeared from blood, liver, kidneys and fat-tissues, and the ChE activity in the serum, erythrocytes and brain was rapidly normalized. Dichlofenthion disappeared very slowly from poisoned rats due to its fat-solubility. ChE activity was inhibited for a long time by dichlofenthion released from adipose reservoirs in the whole body, especially in 40-week-old rats, and normal and obese rats at 80 weeks of age. Three-week-old rats, which were at a sexually immature developmental stage, showed mild symptoms of dichlofenthion poisoning. By contrast, 7-week-old rats were poisoned most severely with dichlofenthion and their ChE activity was the most severely inhibited among 3-, 7-, 40-and 80-week-old rats. The recovery of ChE activity in rats poisoned with fenitrothion was the most protracted because of the rapid aging of ChE phosphorylated by fenitrothion, although fenitrothion disappeared more rapidly from rat tissues than dichlofenthion.These findings in rats demonstrated that the pattern of recovery and the degree of symptoms of acute organophosphorus poisoning differed with age and the organophosphate.