Human Poisoning with Chlorpyrifos and Cypermethrin Pesticide Mixture: Assessment of Clinical Outcome of Cases Admitted in a Tertiary Care Hospital in Taiwan

BACKGROUND AND PURPOSE: There is an overall paucity of data regarding the human toxicity of chlorpyrifos and cypermethrin pesticide mixture. Both organophosphate and pyrethroid insecticides are metabolized by carboxylesterases. Thus, its pesticide combination, organophosphates may boost the toxicity of pyrethroids via inhibited its detoxification by carboxylesterases. This study examined the clinical course, laboratory tests, and outcomes of patients with chlorpyrifos, cypermethrin or their pesticide mixture poisoning, and to determine what association, if any, might exist between these findings. PATIENTS AND METHODS: Between 2000 and 2021, 121 patients poisoned with chlorpyrifos, cypermethrin, or their pesticide mixture were treated at Chang Gung Memorial Hospital. Patients were categorized as chlorpyrifos (n=82), cypermethrin (n=27) or chlorpyrifos and cypermethrin (n=12) groups. Demographic, clinical, laboratory and mortality data were collected for analysis. RESULTS: The patients experienced a broad range of clinical symptoms, including aspiration pneumonia (44.6%), salivation (42.5%), acute respiratory failure (41.3%), acute kidney injury (13.9%), seizures (7.5%), hypotension (2.6%), etc. Leukocytosis (12,700±6600 /uL) and elevated serum C-reactive protein level (36.8±50.4 mg/L) were common. The acute respiratory failure rate was 41.3%, comprising 48.8% in chlorpyrifos, 11.1% in cypermethrin as well as 58.3% in chlorpyrifos and cypermethrin poisoning. Patients with chlorpyrifos and cypermethrin pesticide mixture poisoning suffered higher rates of acute respiratory failure (P=0.001) and salivation (P=0.001), but lower Glasgow Coma Scale score (P=0.011) and serum cholinesterase level (P<0.001) than other groups. A total of 17 (14.0%) patients expired. The mortality rate was 14.0%, including 17.1% in chlorpyrifos, 3.7% in cypermethrin as well as 16.7% in chlorpyrifos and cypermethrin poisoning. No significant differences in mortality rate were noted (P=0.214). CONCLUSION: Chlorpyrifos pesticide accounted for the major toxicity of the pesticide mixture. While the data show a higher rate of respiratory failure in the chlorpyrifos and cypermethrin pesticide mixture group than others, other measures of toxicity such as mortality and length of stay were not increased.