Introduction: We assessed the effect of the pesticide regulations implemented in 2011 on suicide trend in Kerala state of India.Materials and methods: Data were collected from case records of suicide autopsies done in a single tertiary care hospital in Thrissur district of Kerala in 2001-2020. Linear trends in overall suicide rates were identified using joinpoint regression analysis. We used Poisson regression models to estimate the annual expected number of suicides in 2011-2020 and calculated the rate ratios between the observed number of suicide and that expected according to the linear pre-ban suicide trend (2005-2010).Results: There were a total of 14,593 suicide autopsies (2501 pesticide autopsies) in 2001-2020. Carbofuran was the commonest pesticide identified, followed by quinalphos, zinc phosphide, and chlorpyrifos. In 2011-2020, overall suicide rates were 22%-48% and pesticide suicide rates were 20%-55% lower than those expected according to pre-ban suicide trends (2005-2010), with the only exception of a 16% higher-than-expected pesticide suicide rate in 2011. There was no change in trend in hanging suicides.Conclusion: Lower-than-expected overall and pesticide suicide rates were found in Thrissur district after the 2011 bans of pesticides in Kerala, with no evidence of means replacement to hanging.
Keywords: Pesticide; Poisson regression; epidemiology; joinpoint regression; suicide.