Exposure to Organophosphate pesticides (OPs) affects neurotransmitter function in the brain. Changes in serotonin function can result in mood swings, depression, irritability and anger. OP exposure may therefore increase suicide risk by increasing impulsivity and/or depression.Methods
To evaluate whether long-term exposure to OPs is associated with increased risk for attempted suicide and whether increasing levels of exposure are associated with increasing risk of attempting suicide, a case-control study compared 200 adult patients admitted to two teaching hospitals in the Western Cape with a diagnosis of attempted suicide (cases) to 200 age- and gender-matched control patients admitted for unrelated conditions. Exposure assessment was based on (a) work and environmental history; (b) quantification of OP metabolites in hair. Other measures include a 12-item Aggression Questionnaire, the Barratt Impulsiveness Scale and the Centre for Epidemiologic Studies Depression Scale (CESD-D).Results
Of the case and controls, 89% and 82%, respectively reported a history of occupational pesticide exposure and 12% and 13% reported a history of environmental pesticide exposure. There were significant associations (p<0.001) between being a case and high scores for depression, aggression, impulsivity and AUDIT. There was no association with a history of occupational or environmental exposure to OPs. Hair samples were harvested from only 24% of cases and controls. Preliminary analysis of hair metabolites did not confirm any association between OP exposure and suicide attempts.Discussion
Psychological correlates of suicide attempt were consistent with the literature. The absence of any associations with environmental and/or occupational exposures may result from exposure misclassification. Participants were reluctant to give hair samples and this was aggravated by frequent use of synthetic hair braids in women and shaven scalps in men. Low return on hair samples in this population reduced the power to detect associations.