Occupational heat exposure and its impact on kidney health among cashew workers

Rising temperatures increase workers' risk of heat-related illnesses due to heat stress (HS). Chronic Kidney Disease of unknown etiology (CKDu) is rising in non-agricultural workers in hot climates. Dehydration, heat stress, and physical exertion can damage cashew workers' kidney health.

In 2020-2021, 262 cashew workers in Cuddalore, Tamil Nadu were assessed for Wet Bulb Globe Temperature (WBGT), and job-specific American Conference of Governmental Industrial Hygienists standard was used to evaluate workload. "High heat-exposed" meant heat stress exceeded the Threshold Limit Value for safe manual work (27.5 °C for heavy and 28 °C for moderate physical activity). Heat Strain Indicators (HSIs) such as Tympanic Temperature (Ttemp), Sweat Rate (SwR), Urine Specific Gravity (USG), and urine dipstick parameters were measured in all workers, however serum creatinine was measured only in 100 workers. Glomerular Filtration Rate (eGFR) was calculated using the CKD-EPI equation. A standardized questionnaire assessed heat-related health symptoms.

Over 65% of workers experienced wet bulb globe temperature exposures exceeding the threshold limit value (Avg.- wet bulb globe temperature 30.4 °C ± 1.8 °C). Ninety-five percent of heat-exposed workers experienced at least one of the physiological heat strain indicators. The risk of urogenital symptoms was 7.7 times greater among high-heat-exposed workers (95% CI 3.4-17.1), which corroborates well with the measured post shift urine specific gravity (37%). Despite controlling for relevant confounders (age & gender), high-heat-exposed workers had 3.5-fold higher odds of eGFR < 90 ml/min/1.73 m² compared to less-exposed workers (95% CI 1.1-10.6).

Persistent heat stress promotes heat-related disorders in cashew workers and lowers eGFR. This needs further investigation to determine its longer term effects on kidney function. Workplace cooling solutions that reduce heat stress are critically needed to protect the kidneys and ensure occupational health.