Mortality and factors associated with phosphide poisoning: prospective cohort study

Aluminum and zinc phosphides are solid fumigants for pest control. Metal phosphide poisoning (PP) is common in suicide and suicide attempts. In Mexico, zinc phosphide is easily available, and is a common agent in poisonings.

To identify mortality in PP, and associated factors in a poison control center.

Prospective cohort study. The starting point was the exposure (PP) and it was made a follow-up on the outcome (mortality and non-mortality). Main factors associated to PP outcome were assessed (e.g.: personal and clinical factors, duration of poisoning, detoxification, and radiographic evidence of poisoning). It was used relative risk (RR) as a risk estimator with 95% CI, as well as chi-squared with Fisher’s exact test, Kaplan-Meier survival curves, and Log- Rank test as a comparative mean.

44 exposed patients, and 88 non-exposed were followed up. Mortality rate in PP was of 16% in acute phase patients; there were no deaths in either subacute or chronic phases. Mortality risk was 14 (95% CI, 2 110). Main factors associated with increased mortality were: time of first medical assistance > 6 hours, RR = 15 (95% CI, 1.7-128); dose of poison ≥ 1 bottle or 1 tablet, RR = 14 (95% CI, 1.8-108); radiographic evidence of poisoning, RR = 10 (95% CI, 1.3 77).

Metal PP has a high mortality rate and is associated to long periods of exposure to the toxic chemical due to ineffective detoxification.