Urinary dialkyl phosphate levels before and after first season chlorpyrifos spraying amongst farm workers in the Western Cape, South Africa

Abstract

The study investigated urinary levels of dialkyl phosphates resulting from pesticide exposure amongst 40 farm workers. Workers were tested (urinary dialkyl phosphate levels, anthropometry, short exposure questionnaire) before and after the first day of seasonal chlorpyrifos spraying. Median baseline urinary dialkyl phosphates was high amongst both non-applicators (1587.5 μg/g creatinine, n = 8) and applicators (365.6 μg/g creatinine, n = 9). There was not much evidence of an increase in post-spray dialkyl phosphates levels from pre-spray levels amongst both applicators and non-applicators. Hours mixing, spraying, driving a tractor and hours worked by non-applicators were not significantly associated with an increase in post-spray dialkyl phosphate levels, adjusting for age, height, weight, gender, use of empty pesticide containers and self-reported kidney problems. Past applicator status was weakly positively associated with pre-spray dialkyl phosphate levels adjusting for age, height, weight, and gender, self-reported kidney problems, smoking and alcohol (β= 1019.5, p = 0.307, R²= 0.28). The high dialkyl phosphate levels call for an epidemiological investigation into the health effects of organophosphorous pesticides.

Keywords:

• Pesticide exposure
• bio-monitoring
• chlorpyrifos
• dialkyl phosphates
• organophosphates
• spraying
• mixing
• drift
• occupational
• environmental

Acknowledgments

The National Research Foundation (SA), the University of Cape Town's Faculty of Health Sciences Research Committee and the NIH and The University of Michigan/US National Institutes of Health/Forgarty International Centre- Southern African Programme in Environmental and Occupational Health are thanked for their financial support.