Fenitrothion has been reported as one of the organophosphates causing so called "intermediate syndrome"--clinical entity of still unclear reasons. That is why we decided to perform a retrospective examination of oral intoxication with this compound. Clinical course of 16 cases were analysed. Clinical state on admission, AChE activity and pesticide concentration in blood were considered. Gastric lavage, atropine and oximes were included in the treatment. 6 patients died in the period of 5 to 22 days (mean 11.8) from poison intake. All 6 revealed slight signs of poisoning at the time of admission (first 24th). AChE was moderately inhibited. Patients' clinical state was deteriorating and AChE activity was decreasing during next 48 h even though oximes therapy was applied. Intubation and mechanical ventilation was required. Fenitrothion concentration in blood varied from 470 to 8350 ng/ml (mean 2823 ng/ml). In 3 fatal cases toxicological examination of autopsy tissue was done. High fenitrothion concentration was found in adipose tissue and also in the brain. In the group of 10 recovered patients "intermediate syndrome" was not observed in 3 only. AChE activity returned to normal quickly. Fenitrothion concentration ranged from 96 to 360 ng/ml (mean 202 ng/ml). In the remaining 7 clinical state became worse during next 48-72 hours after temporary improvement. Respiratory failure and increasing AChE activity inhibition were major signs. Fenitrothion concentration varied from 180 to 3020 ng/ml (mean 1690 ng/ml). AChE inhibition persisted even for 30 days from poisoning.
