Some pesticides are more toxic to humans than previously thought and the World Health Organization should adjust its figures accordingly to reduce self-poisoning.
So says Andrew Dawson at the University of Peradeniya in Sri Lanka, who studied 7461 pesticide-suicides and attempted suicides.
Agricultural pesticides are the most common means of suicide worldwide, resulting in more than 250,000 deaths each year. In their 6-year study, Dawson's team found that, depending on the pesticide taken, fatality of cases arriving at two Sri Lankan hospitals varied between 0 and 42 per cent. This marked variation in lethality was observed for compounds within the same chemical and/or WHO toxicity classification of pesticides and for those used for similar agricultural indications.
They found certain pesticides were far more toxic to humans than the WHO ranks them based on animal studies. They also discovered pesticides that are similarly effective in agricultural practice but vary in their toxicity to humans.
The WHO should incorporate the new data into their pesticide-toxicity classification, which informs policy decisions, to better address the public health problem of suicide, says Dawson.
Dawson and his team aimed to determine the relative human toxicity of formulated agricultural pesticides to improve the effectiveness of regulatory policy.
They examined the case fatality of different agricultural pesticides in a prospective cohort of patients presenting with pesticide self-poisoning to two clinical trial centers for a 6.5 year period. Dawson found that a specific pesticide was identified in 7,461 patients; 1,841 ingested an unknown pesticide.
The human data provided toxicity rankings for some pesticides that contrasted strongly with the WHO toxicity classification based on rat toxicity. Basing regulation on human toxicity will make pesticide poisoning less hazardous, preventing hundreds of thousands of deaths globally without compromising agricultural needs. Ongoing monitoring of patterns of use and clinical toxicity for new pesticides is needed to identify highly toxic pesticides in a timely manner.
Journal reference: PLoS Medicine, DOI: 10.1371/journal.pmed.1000357