A Cohort Study of Pesticide Poisoning and Depression in Colorado Farm Residents

Purpose Depressive symptoms have been associated with pesticide poisoning among farmers in cross-sectional studies, but no longitudinal studies have assessed the long-term influence of poisoning on depressive symptoms. The purpose of this study was to describe the associations between pesticide poisoning and depressive symptoms in a cohort of farm residents. Methods Farm operators and their spouses were recruited in 1993 from farm truck registrations using stratified probability sampling. The Center for Epidemiologic Studies-Depression scale was used to evaluate depression in participants using generalized estimating equations. Baseline self-reported pesticide poisoning was the exposure of interest in longitudinal analyses. Results Pesticide poisoning was significantly associated with depression in three years of follow-up after adjusting for age, gender, and marital status (odds ratio [OR] 2.59; 95% confidence interval [CI] 1.20–5.58). Depression remained elevated after adjusting for health, decreased income, and increased debt (OR 2.00; CI 0.91–4.39) and was primarily due to significant associations with the symptoms being bothered by things (OR 3.29; CI 1.95–5.55) and feeling everything was an effort (OR 1.93; CI 1.14–3.27). Conclusions Feeling bothered and that everything was an effort were persistently associated with a history of pesticide poisoning, supportive of the hypothesis that prolonged irritability may result from pesticide poisoning.