Pesticide Regulation for Suicide Prevention

Suicide is one of the leading causes of premature mortality worldwide. The World Health Organization (WHO) estimates that there are approximately one million suicides every year; rates are particularly high in rural Asia. Ingestion of pesticides in acts of self-harm accounts for one third of the global burden of suicide. These deaths are readily preventable as research shows that restricting access to highly lethal methods of suicides saves lives.¹

This innovation aims to ban the sale of the agricultural pesticides that are most toxic when ingested by humans: namely all WHO toxicity Class I pesticides. In addition, following research on the local epidemiology of fatal pesticide poisoning, the ban of WHO toxicity Class II pesticides that are local problems for suicide (in Sri Lanka: endosulfan, paraquat, and organophosphorus insecticides such as dimethoate and fenthion).¹

By providing advice to farmers on locally acceptable alternative practices (e.g. IPM) or less toxic pesticides, and by working with industry, such bans in Sri Lanka have been shown to be acceptable to farmers and to have minimal effect on agricultural costs or crop yields.

There is strong evidence that restriction of access to commonly used, highly lethal methods of suicide leads to an overall reduction in suicides. This is because suicide attempts are often made impulsively in moments of crisis when the ready availability of highly-lethal methods means the suicide attempt is more likely to result in death. Thus in rural areas of developing countries around 10% of episodes of self-poisoning are fatal because of the high toxicity of commonly used pesticides (e.g. the case fatality for Paraquat self-poisoning is 50-60%).  In contrast in the UK, where paracetamol is the substance most frequently ingested by people who attempt suicide, death rates are low because the case fatality following ingestion of paracetamol is <0.5%.

The other good example of how restriction of access to means of suicide can save lives comes from Norman Kreitman’s assessment of the impact on suicide rates of changes in the UK’s domestic gas supply in the 1950s-60s. In the 1950s domestic gas poisoning accounted for almost half of all suicides in the UK. The high carbon monoxide content of domestic gas accounted for it being highly lethal. In the 1960s, the UK’s domestic gas supply changed from coal gas (with its high carbon monoxide content) to natural gas (with very low carbon monoxide levels). This made suicide by domestic gas poisoning almost impossible. Rates of domestic gas poisoning fell to almost zero by the 1970s and, crucially, there was no compensatory rise in suicides using other methods – there was no “method substitution” to other equally lethal methods. Several thousand lives were saved.³

The particularly successful features of the innovation are:

• The intervention is low cost and simple to implement by a decision taken by the Ministry of Agriculture
• By saving lives, it allows patients to subsequently be helped with psycho-social support or psychiatric treatment 
• In addition to saving lives, the innovation markedly reduces health care costs: treatment of patients with pesticide self-poisoning often necessitates several weeks of expensive intensive care in already overstretched hospitals 
• While bans on highly toxic pesticides do not stop people self-poisoning, the alternative products that people then take (such as medicines or newer pesticide products) are much less toxic in overdose so are  less likely to lead to death or prolonged periods of hospitalization