Organophosphate pesticide exposure as a risk factor for attempted suicide in Cape Town, South Africa: A case-control study

Pesticides are a commonly used agent for suicide in many Low- and Middle-Income countries (LMICs). However, accumulating evidence suggests that exposure to organophosphate (OP) pesticide may also increase the risk of suicide. We conducted a hospital-based case-control study to investigate whether prior household, garden or occupational OP exposure were associated with attempted suicide using conditional logistic regression modeling. Participants who attempted suicide with any means and were admitted to two Western Cape Province hospitals in South Africa were compared to a sample of controls matched by age, sex and time of admission with unrelated conditions, between August 2015 and August 2017. The means of attempted suicide was not recorded. OP exposure was determined by dialkyl phosphate (DAP) metabolites detected in hair and by environmental and occupational history. Approximately 85% of participants reported using pesticides in the home or garden and 15% of participants reported current or past occupational exposure while working on a farm. Attempted suicide was not associated with reported home or garden OP use (Odds ratio [OR] = 0.59, 95%CI 0.33-1.04), hair DAP metabolites (OR = 1.00, 95%CI 0.98-1.02) or current or past agricultural work (OR = 1.08, 95%CI 0.62-1.87), but was associated with hazardous drinking and unemployment with no household income. We found no evidence that attempted suicide was associated with environmental or occupational pesticide use in an urban South African population attending an emergency center.