Research: solvent exposure increases depressive symptoms among farmers

Although organic solvents are often used in agricultural operations, neurotoxic effects of solvent exposure have not been extensively studied among farmers. To fill this knowledge gap, a team including University of Kentucky College of Public Health researchers conducted an analysis examined associations between questionnaire-based metrics of organic solvent exposure and depressive symptoms among farmers. Their findings appear in the International Archives of Occupational and Environmental Health.

Investigators analyzed questionnaire responses from 692 male Agricultural Health Study participants; solvent type and exposure duration were assessed. An “ever-use” variable and years of use categories were constructed for exposure to gasoline, paint/lacquer thinner, petroleum distillates, and any solvent. Depressive symptoms were ascertained with the Center for Epidemiologic Studies Depression Scale (CES-D); scores were analyzed separately as continuous (0–60) and dichotomous (<16 versus ≥16) variables. Multivariate linear and logistic regression models were used to estimate crude and adjusted associations between measures of solvent exposure and CES-D score.

Forty-one percent of the sample reported some solvent exposure. The mean CES-D score was 6.5 (SD 6.4; median 5; range 0–44); 92% of the sample had a score below 16. After adjusting for covariates, statistically significant associations were observed between ever-use of any solvent, long duration of any solvent exposure, ever-use of gasoline, ever-use of petroleum distillates, and short duration of petroleum distillate exposure and continuous CES-D score (p < 0.05). Although nearly all associations were positive, fewer statistically significant associations were observed between metrics of solvent exposure and the dichotomized CES-D variable.

Investigators observed that solvent exposures were associated with depressive symptoms among farmers. This led to the conclusion that efforts to limit exposure to organic solvents may reduce the risk of depressive symptoms among farmers.

Authors include Dr. Miriam Siegel, a graduate of the UK College of Public Health currently serving in the Epidemic Intelligence Service of the CDC, and Dr. Wayne Sanderson, professor of Epidemiology and director of the Southeast Center for Agricultural Health and Injury Prevention.