Occupational heat exposure and chronic kidney disease risk under climate warming: a retrospective cohort study of petrochemical workers with mechanistic insights

The modifying role of climate warming in the association between occupational heat exposure and chronic kidney disease (CKD), and the related biological mechanisms, remains incompletely understood among petrochemical workers. We conducted a retrospective cohort study of 2,649 petrochemical workers in southeastern China between 2013 and 2022. Occupational heat exposure was assessed using on-site wet-bulb globe temperature (WBGT) measurements, reflecting the overall workplace thermal load arising from ambient temperature, process-related heat sources, humidity, and air movement. Incident CKD was defined according to the 2024 Kidney Disease: Improving Global Outcomes (KDIGO) guidelines. Long-term ambient temperature data were incorporated to evaluate effect modification by climate warming and ambient temperature background. In addition, mediation analyses of blood-based biomarkers and a nested case–control metabolomics study were conducted to explore potential biological mechanisms. During a median follow-up of 7.1 years, 386 incident CKD cases were identified. Occupational heat exposure was significantly associated with an increased risk of CKD (HR = 1.40, 95% CI: 1.13–1.71). This association was significantly amplified under conditions of greater climate warming and higher annual mean ambient temperatures (P-interaction < 0.001). Mediation analyses indicated that uric acid, hemoglobin, and albumin partially mediated the association between occupational heat exposure and CKD risk. Metabolomic analyses further revealed shared metabolic alterations related to the accumulation of gut-derived uremic toxins and disturbances in amino acid metabolism. Occupational heat exposure was associated with an elevated risk of CKD among petrochemical workers, and this risk is likely further intensified in the context of ongoing climate warming. These findings highlight the importance of incorporating climate context into occupational heat-related health risk assessments and suggest that integrating routine biomarkers with metabolomic features may enhance early identification and prevention of CKD among occupational heat-exposed workers.