Exposure to pesticides and mental disorders in a rural population of Southern Brazil

Introduction: Exposure to pesticides has been associated with mental disorders, especially in occupationally exposed populations, such as farmers. This effect has been attributed to the neurotoxic and endocrine-disrupting activity of pesticides, as suggested by experimental studies.

Objective: To determine the prevalence of common mental disorders and self-reported depression, and analyze their association with the exposure to pesticides in a rural population resident in the municipality of Dom Feliciano, Rio Grande do Sul, where tobacco farming is the main economic activity.

Methodology: A cross-sectional study evaluating the prevalence of common mental disorders and self-reported depression in a sample of 869 adult individuals resident in Dom Feliciano, between October 2011 and March 2012 was performed. The evaluation of common mental disorders was performed using the Self-Reporting Questionnaire (SRQ-20), setting a cutoff point of 8 for both genders. A standardized questionnaire was used to obtain information on self-reported depression upon prior diagnosis by a health professional, and self-reported exposure to pesticide. In order to evaluate the association between exposure to pesticides and mental disorders, a non-conditional multivariate logistic regression analysis was performed.

Results: The prevalence of common mental disorders and self-reported depression in the sample population were 23% and 21%, respectively. Among individuals who reported depression, an increase of 73% was observed in the odds of pesticide exposure at an age equal to or less than 15 years. There was a positive association between self-reported pesticide poisoning and common mental disorders (OR=2.63; 95% CI, 1.62-4.25) as well as self-reported depression (OR=2.62; 95% CI, 1.63-4.21). Individuals who reported depression had a greater odds of exposure to pyrethroids (OR=1.80; 95% CI, 1.01-3.21) and aliphatic alcohol (OR=1.99; 95% CI, 1.04-3.83). An SRQ-20≥8 was associated with an approximately seven times higher odds of exposure to aliphatic alcohol (95% CI, 1.73-27.53). Self-reported depression positively correlated with a greater period of exposure to dinitroaniline (OR=2.20; 95% CI, 1.03-4.70) and sulphonylurea (OR=4.95; 95% CI, 1.06-23.04).

Conclusion: The results suggest that exposure to pesticides could be related mental disorders. However, other common risk factors in tobacco farming, the main local economic activity, cannot be excluded.