Introduction: The association between pesticide use and an increased suicide risk is a controversial issue. Previous studies have shown higher rates of suicide among agricultural workers and people living in small municipalities, but have not identified the causes of these results. Objective: To investigate the association between pesticide exposure and suicide rates. Methods: Crude suicide rates of a 15-year time series (1996-2010) were examined, followed by an ecological study using age-standardized suicide rates for the period 2006-2010. The unit of analysis was all 558 Brazilian micro-regions. Pesticide exposure was evaluated according to the proportion of farms that used pesticides and had reported cases of pesticide poisonings. The statistics were analysed using Pearson's correlation and multiple linear regression adjusted for socioeconomic, demographic and cultural factors. Results: Among the age group that was analysed, the mean suicide rate was 6.4 cases/100,000 per year in the 2006-2010 period, with a male/female ratio of 4.2. The times series showed that there were higher suicide rates among people aged 35-64 years and among men aged 15-34 years. The ecological analysis showed that the suicide rates were higher in micro-regions with a higher proportion of farms run by 35-64 year olds, female workers and on farms with better economic indicators (higher farming income, level of mechanization and farm area). There was a positive association between the Catholic religion and suicide rates. Micro-regions with a greater use of pesticides, and with a high proportion of pesticide poisoning had the highest suicide rates for all three groups analysed: both genders, men, and women (p ranging from 0.01 to p< 0.001). Conclusion: This study reinforces the hypothesis that pesticide use and pesticide poisoning increase the suicide rates. However, due to the limitations of the study's ecological design, such as ecological fallacy, further appropriately designed studies are needed to confirm the causal relationships.
Faria, N. M. X., Fassa, A. G., & Meucci, R. D. (2014). Association between pesticide exposure and suicide rates in Brazil. NeuroToxicology, 45, 355–362. https://doi.org/10.1016/j.neuro.2014.05.003