Epidemiological evidence from south Indian working population-the heat exposures and health linkage.

Changing climate and rising temperatures are predicted to affect millions of workers due to heat stress risks, especially in tropical settings. We used a cross-sectional study design to profile the heat exposures of ~1500 workers from eight-industrial sectors using a QuesTemp wet bulb globe temperature (WBGT) monitor, quantified the heat-strain indicators viz., rise in Core Body Temperature (CBT), Sweat Rate (SwR), and Urine Specific Gravity (USG) by standard methods and evaluated the health impacts of heat stress using a structured questionnaire. Heat exposures (Avg.WBGT: 28.4 ± 2.6 °C) exceeded the Threshold Limit Value (TLV) for 70% of workers and was significantly associated with the rise in CBT >1 °C in 11.3% and elevated USG >1.020 in 10.5% of the workers. The heat-exposed workers had 2.3 times higher odds of reporting adverse health outcomes (84%) compared to the unexposed workers (95% CI: 1.74-3.19; p value ≤ 0.0001). Mild reduction in kidney function observed in 49% of salt - pan workers, and a high prevalence of kidney stones (33%) among the 91 steelworkers subjected to kidney ultrasound had a significant association with chronic high WBGT exposure above the TLV (p value < 0.034). Further, in-depth assessments are warranted to develop strategies for interventions and protective labor policies to avert adverse occupational health and productivity consequences for millions of workers globally, especially in the rising temperature scenario.