Paraquat exposure of backpack sprayers in agricultural area in Thailand

Abstract

Thai agriculturists heavily used paraquat in agricultural areas to control weed and grasses. This study determined paraquat exposure among backpack sprayers in Thailand and identified determinants of occupational exposure. Breathing zone air and dermal samples were collected from 57 backpack sprayers while spraying. Spot urine samples were collected on the day before spraying, end of spraying event and the next day after spraying. The subjects were interviewed about general demographics, agricultural activities, pesticide application and personal protective equipment used while applying paraquat. Paraquat concentrations in urine samples, air samples and dermal samples were determined by HPLC with a fluorescence detector. The median IQR of urinary paraquat concentrations on the day before spraying, end of spraying event, the next day after spraying were 2.51 (0.81–5.59), 8.23 (3.3–13.73) and 3.48 (1.03–8.19) µg/g creatinine, respectively. Concentrations of air samples and total dermal exposures were 5.15 (2.28–10.12) µg/m³ and 92.66 (34.37–1647.46) µg/hr, respectively. Use of battery powered backpack sprayer and standing upwind effectively reduced inhalation exposures. Wearing a long sleeve shirt, long pants, boots, latex gloves and balaclava could reduce paraquat concentration on dermal exposure among backpack sprayers.

Keywords:

• Paraquat
• agriculture
• inhalation exposure
• dermal exposure
• Thailand

Acknowledgments

We would also like to thank the Center of Excellence on Environmental Health and Toxicology (EHT) for laboratory equipment, and all the participants and health-promoting hospital staff in Nakorn Sawan Province. This study protocol was approved by the Ethics Review Committee for Human Research, Faculty of Public Health, Mahidol University, Thailand (COA. No. MUPH 2015-146).

Additional information

Funding

This research was financially supported by the Thailand Research Fund (TRF) through the Royal Golden Jubilee Ph.D. Program (grant number PHD/0149/2556) and the CWEND GEOHealth Hub supported by NIH the Fogarty International Center, National Institutes of Environmental Health Science and the Center for Disease Control under Award Numbers U01 TW010091 and U2R TW010088.