Risk of kidney stone among workers exposed to high occupational heat stress - A case study from southern Indian steel industry.

BACKGROUND

Predicted temperature rise is likely to increase the risks of development and progression of renal/urologic anomalies for workers engaged in physically exerting and high-heat occupations.

METHODS

We conducted a cross-sectional study with 340 steelworkers engaged in moderate to heavy labour with ≥3 year's heat exposures and assessed Wet Bulb Globe Temperature (WBGT) and heat-strain indicators. We captured self-reported heat-strain and kidney symptoms using validated questionnaires and subjected 91 workers to renal ultrasound upon referral of an occupational health specialist to detect and confirm any structural renal anomalies/stones.

RESULTS

The results show that heat exposures (Avg.WBGT = 33.2 °C ± 3.8 °C) exceeded the Threshold Limit Value (TLV) for 220 workers. 95% of the workers reported symptoms of heat strain and dehydration and significant associations between heat exposures, rise in Core Body Temperature (CBT) (p = 0.0001) and Urine Specific Gravity (USG) (p = 0.018) were observed. Of the 91 workers subjected to renal ultrasound, 33% were positive for kidney/ureteral stones (n = 25) & other structural renal anomalies (n = 5). Renal/urologic anomalies were higher in the heat-exposed workers (AOR = 2.374; 95% C.I = 0.927 to 6.077; p = 0.072) 29% of workers were from exposed group and 4% were from unexposed group. Years of exposure to heat (≥5 vs <5) were significantly associated with the risk of renal anomalies/calculi.

CONCLUSION

The preliminary finding concludes that high-heat stress combined with a heavy workload and chronic dehydration are high-risk factors for adverse renal health and calls for the urgent need for cooling interventions, enhanced welfare facilities, and protective labour policies to avert adverse health consequences for few million workers in the climate change scenario.