Urinary excretion of diethylphosphorus metabolites in persons poisoned by quinalphos or chlorpyrifos

Abstract

The urinary excretion rates of diethyl phosphate and diethyl phosphorothioate and changes in blood cholinesterase activities were studied in fifteen persons self-poisoned either by the organophosphorus pesticide quinalphos (twelve persons) or by chlorpyrifos (three persons). The organophosphate poisoning was always indicated by a significant depression of serum and/or red blood cell cholinesterase activities. The return of serum cholinesterase activity in the range of referent values took more than 30 days and had a different course in different persons. The most rapid increase in red blood cell acetylcholinesterase activity was noted within 24 h after the first treatment with oximes Pralidoxime and/or HI-6. None of the spot urine samples, collected daily after admission of persons to hospital, contained measurable quantities of the parent pesticide. There was no correlation between the maximum concentration of total urinary diethylphosphorus metabolites normalized to creatinine and the initial inhibition of blood cholinesterase activities measured in samples collected on the day of admission to hospital. The excretion of metabolites followed the kinetics of a biphasic reaction. The half-time of urinary metabolites concentration decrease in the fast excretion phase in quinalphos poisoned persons was 5.5-14.2 h (eight persons) and 26.8-53.6 h (four persons) and in chlorpyrifos poisoned persons 3.5-5.5 h. The half-time for the slow excretion phase ranged from 66.5 to 127.9 h in all persons and for both compounds. For a given person, the rates of excretion of diethyl phosphate and diethyl phosphorothioate were about the same. However, in quinalphos poisoned persons the proportions of single metabolites in total diethylphosphorus metabolites varied with the initial maximum concentration of total metabolites.(ABSTRACT TRUNCATED AT 250 WORDS)

Critical Evaluation of Chlorpyrifos’ Breast Cancer Risk

“…Another study estimated the half-life in humans to be 3.5 to 5.5 hours based on three cases of chlorpyrifos poisonings (Vasilic et al, 1992). However, the effect on serum cholinesterase enzymes was found to persist for many days after the poisonings in this study.…”

Review of the Toxicology of Chlorpyrifos With an Emphasis on Human Exposure and Neurodevelopment

“…As described in Section II.C, numerous chlorpyrifos metabolites have been identified in urine in a subject who ingested a near lethal dose of chlorpyrifos, including numerous glutathione-derived metabolites (Bicker et al, 2005a). Vasilic et al (1992) investigated the urinary excretion of diethylphosphate and diethylthiophosphate in three individuals who ingested toxic doses of chlorpyrifos and were treated with oximes. No parent compound was detected in the urine.…”

Mechanisms of Organophosphate Toxicity and Detoxication with Emphasis on Studies in Croatia

“…Procedures used or developed in Croatia for the analysis of dimethyl-and diethyl-phosphorus metabolites and parent compounds are summarised in reference (37). Over a decade, several studies were conducted on workers spraying OP pesticides and on accidentally or intentionally poisoned individuals, comprising about 130 subjects (38)(39)(40)(41)(42)(43). The OP compounds involved were methidathion, amidothion, azinphos-methyl, quinalphos, chlorpyrifos, phosalone, thiomethon and malathion.…”