Is Cumulated Pyrethroid Exposure Associated With Prediabetes? A Cross-sectional Study

ABSTRACT

Pyrethroids are a class of insecticides used widely for vector control programs. Acute pyrethroid poisoning is rare, but well documented, whereas effects of cumulative exposure are insufficiently described, including possible negative effect on glucose regulation. The objective of this study was to investigate an association between exposure to pyrethroids and abnormal glucose regulation (prediabetes or diabetes). A cross-sectional study was performed among 116 pesticide sprayers from public vector control programs in Bolivia and 92 nonexposed controls. Pesticide exposure (duration, intensity, cumulative exposure) was assessed from questionnaire data. Participants were asked about symptoms of diabetes. Blood samples were analyzed for glycosylated hemoglobin (HbA_1c), a measure of glucose regulation. No association was found between pyrethroid exposure and diabetes symptoms. The prevalence of abnormal glucose regulation (defined as HbA_1c ≥ 5.6%) was 61.1% among sprayers and 7.9% among nonexposed controls, corresponding to an adjusted odds ratio (OR [95% confidence interval]) for all sprayers of 11.8 [4.2–33.2] and 18.5 [5.5–62.5] for pyrethroid-exposed only. Among sprayers who had only used pyrethroids, a significant positive trend was observed between cumulative pesticide exposure (total number of hours sprayed) and adjusted OR of abnormal glucose regulation, with OR 14.7 [0.9–235] in the third exposure quintile. The study found a severely increased prevalence of prediabetes among Bolivian pesticide sprayers compared with a control group, but the relevance of the control group is critical. Within the spraying group, an association between cumulative exposure to pyrethroids and abnormal glucose regulation was seen. Further studies are needed to confirm this association.

KEYWORDS:

• Abnormal glucose regulation
• diabetes mellitus
• pesticides
• prediabetic state
• pyrethrins
• pyrethroids

ACKNOWLEDGMENTS

The authors wish to thank the Bolivian Ministry of Health and Sports, The Departmental Health Service of Cochabamba, The Departmental Health Service of Santa Cruz, The National Institute of Occupational Health in La Paz, and The Institute of Genetics in La Paz for their cooperation in the study. In particular, the authors would like to thank the following persons for their effort in planning and carrying out the data collection: Dr. Noemi Tirado Bustillos and Dr. Rolando Paz Bonilla (The Institute of Genetics), Dr. Maria Angelica Urzagaste Soliz (The National Institute of Occupational Health), and Dr. Giovanna Condarco Arispe (The Plagbol Foundation, La Paz, Bolivia).