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Published on: March 14, 2019
Differences between organophosphorus insecticides in human self-poisoning: a prospective cohort study
Michael Eddleston1, Peter Eyer, Franz Worek
1South Asian Clinical Toxicology Research Collaboration, Centre for Tropical Medicine, University of Oxford, Churchill Hospital, Oxford, UK. eddlestonm@eureka.lk
Lancet (London, England)
|October 26, 2005
Summary
Organophosphorus insecticide poisoning varies significantly by compound. Dimethoate and fenthion cause higher mortality and intubation rates than chlorpyrifos in humans, contrary to animal toxicity data.
Area of Science:
- Toxicology
- Clinical Medicine
- Environmental Health
Background:
- Organophosphorus (OP) insecticides are widely used, yet OP poisoning is often treated as a uniform condition.
- Existing classifications primarily rely on animal lethal dose data, potentially misrepresenting human toxicity.
- The clinical presentation and severity of OP poisoning can vary significantly among different compounds.
Purpose of the Study:
- To investigate differences in clinical features and poisoning severity among three common organophosphorus insecticides used for self-poisoning in Sri Lanka: chlorpyrifos, dimethoate, and fenthion.
- To compare the human toxicity of these OP compounds, challenging the reliance on animal toxicity data.
- To inform the development of specific management protocols for different OP poisonings.
Main Methods:
- A prospective study of 802 patients with confirmed chlorpyrifos, dimethoate, or fenthion self-poisoning across three hospitals.
- Measurement of blood cholinesterase activity and insecticide concentrations to confirm the causative agent and assess patient response.
- Systematic recording of clinical outcomes, including mortality and need for endotracheal intubation.
Main Results:
- Mortality rates were significantly higher for dimethoate (23.1%) and fenthion (16.2%) compared to chlorpyrifos (8.0%).
- Endotracheal intubation was required more frequently in dimethoate (35.2%) and fenthion (31.3%) poisonings than in chlorpyrifos (15.0%) cases.
- Dimethoate poisoning led to rapid deaths, often from shock, while fenthion poisoning showed delayed respiratory complications. Response to pralidoxime varied, with poorer outcomes for dimethoate and fenthion.
Conclusions:
- Organophosphorus insecticide poisoning is not a monolithic entity; significant variations exist in clinical course, treatment response, and outcomes.
- Human toxicity profiles differ markedly from animal data; chlorpyrifos, highly toxic in rats, is least toxic in humans among the studied compounds.
- Individualized management protocols tailored to specific organophosphorus insecticides are crucial for improving patient outcomes.
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