Taiwan has seen a considerable reduction in pesticide suicide rates over the last three decades. This is most likely to be related to a rapid reduction in the population that is involved in agriculture and exposed to highly hazardous pesticides when Taiwan has experienced rapid industrialisation and rural-to-urban migration over this period. Multiple bans on specific pesticide products at different time points did not seem to impact on pesticide suicide trends, as they did not include a ban on pesticides that caused most deaths such as paraquat, a high-lethality weed killer. Taiwan government recently announced the schedule to ban paraquat products, with the complete ban on use becoming effective in 2019.

In 1987-2010, Taiwan's age-standardised pesticide suicide rates fell from 7.7 to 2.5 per 100,000 (a 67% reduction). In 1987, pesticide poisoning was the most commonly used method of suicide, accounting for 42% of all suicides, but it became the third most common method (12% of all suicides) in 2010. The reduction was paralleled by a 66% fall in the workforce involved in agriculture.

By contrast, there was no strong evidence for an association with trends in pesticide sales and unemployment or bans on selected pesticide products (arrows in Figure; numbers indicate specific formulated pesticide products banned for which name can be found in Chang et al 2012 Clinical Toxicology). The bans did not include products (e.g. paraquat) that accounted for most deaths. They were also mainly restricted to selected high-strength formulated products (e.g. 25.3% emulsifiable concentrate of mevinphos) whilst their equivalent low-strength products (e.g. 10% soluble concentrate of mevinphos) were not banned.

In recent years, pesticide poisoning accounted for 450-500 suicides in a year in Taiwan. Amongst them at least around 200 were due to poisoning from paraquat; this made paraquat the single pesticide accounting for the most deaths by pesticide poisoning in Taiwan. In some rural counties, paraquat poisoning accounted for one in eight suicides.

In Oct 2017, Taiwan Council of Agriculture formally announced the schedule to ban the two remaining pesticide products containing paraquat. A complete ban on the sale and use will become effective from Feb 2019. The impact of the ban on pesticide-related suicides needs to be assessed but is expected to be significant. It may also impact on overall suicide rates in rural areas.

Our pilot project in Taiwan will evaluate the effect of Taiwan's new regulations on paraquat and will collect empirical data regarding suicide by pesticide poisoning to inform suicide prevention strategies in Taiwan. This project is important for improving regulation and policy related to highly hazardous pesticides globally. Through analysing national mortality data, hospital records, and data from interviews with suicide attempters, the study will provide important insight into the burden, distribution, and characteristics of suicide by pesticide self-poisoning and the impact of HHP bans in Taiwan and inform local and global prevention strategies to reduce pesticide suicides.

Chang, S.S., Lu, T.H., Eddleston, M., Konradsen, F., Sterne, J.A., Lin, J.J., and Gunnell, D., Factors associated with the decline in suicide by pesticide poisoning in Taiwan: a time trend analysis, 1987-2010. Clin Toxicol (Phila), 2012. 50: 471-80.
Lin, J.J., Chang, S.S., and Lu, T.H., The leading methods of suicide in Taiwan, 2002-2008. BMC Public Health, 2010. 10: 480.
Chang, S.S., Lu, T.H., Sterne, J.A., Eddleston, M., Lin, J.J., and Gunnell, D., The impact of pesticide suicide on the geographic distribution of suicide in Taiwan: a spatial analysis. BMC Public Health, 2012. 12: 260.