Anurak Wongta, PhD
ANURAK WONGTA
Nominated From: University of Minnesota
Research Site: Chiang Mai University
Research Area: Environmental and Occupational Health
Primary Mentor: Bruce Alexander, PhD
Research Project
Combined Impacts of Heat, Air Pollution, and Pesticides on Respiratory Health of Shan Migrant Agricultural Workers in Northern Thailand
Agricultural workers in northern Thailand face combined risks from extreme heat, high fine particulate matter (PM2.5) during seasonal biomass burning, and intensive pesticide use. Shan migrant flower-farm workers are especially vulnerable due to limited workplace protections, language barriers, and restricted access to health services. Evidence on the interactive effects of heat, PM2.5, and pyrethroid exposure on respiratory health is lacking in tropical low- and middle-income countries. This study will conduct a two-season, repeated-measures pilot among approximately 80 adult Shan workers and a child subset of 40 in Mae Rim District, Chiang Mai. In each round, we will measure spirometry, six-minute walk test, urinary biomarkers of pyrethroid exposure (3-PBA), serum Abamectin in a subset of farmers, fingerstick acetylcholinesterase as a safety screen for organophosphate and carbamate, and 24–48-hour personal monitoring of PM2.5 and heat index. Short symptoms and work-practice surveys will identify modifiable factors such as hydration, use of personal protective equipment, and spray timing. Mixed-effects models will estimate associations between exposures and outcomes, test for combined effects, and evaluate modifiers. Children will provide noninvasive urine samples and symptom checklists to explore household carryover. Results will be returned in plain language through bilingual Thai/Shan community meetings. The study will generate practical safe-spray and heat/PM precautions, build local capacity in spirometry quality control, personal monitoring, and biomarker analysis, and provide pilot data for larger global health studies. Findings are directly relevant to migrant worker safety in Thailand and to agricultural communities in the United States facing overlapping environmental and occupational risks.
Research Significance
This study addresses a critical gap in understanding the combined effects of heat, PM2.5, and pesticide exposure, including both pyrethroids and abamectin, to respiratory health in a vulnerable migrant worker population. Shan agricultural workers face overlapping environmental and occupational risks with limited access to protective equipment and health services. By using repeated measures and biomonitoring, this pilot will generate the first integrated evidence on multiple exposures in tropical agricultural workers, including novel data on abamectin, which is widely used but rarely studied in humans. The findings will provide practical guidance for safe spray timing, hydration, and heat/PM protection, while also informing policies to safeguard migrant laborers. Results are directly relevant to agricultural communities in Thailand and to farmworkers in the United States who face similar risks from combined environmental and occupational exposures. This design balances rigor and relevance, preserving a validated urinary biomarker (3-PBA) while adding field-reflective abamectin data rarely available in migrant flower-farm workers.
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