Exposure characteristics and human health risk of various heavy metal(loid)s in urine of occupational workers for different activities of E-waste recycling

To reach sustainability, e-waste is dismantled and precious materials are extracted for reuse. However, e-waste dismantling poses substantial heavy metal(loid) exposure risks to workers and nearby residents, but process-specific mechanisms and combined risk characteristics remain unclear. We aim to address this gap by studying internal exposure characteristics and human health risk of 14 typical metal(loid)s in urine of e-waste dismantling workers (n = 173) from a recycling industrial park and nearby residents (n = 228). Principal component analysis, job-specific comparisons, partial correlation analysis, and health risk were integrated to clarify exposure characteristics, influencing factors, risks, and uncertainty. Results showed distinct population-specific distributions: workers had higher levels of Zn (405 μg/L), Cu (15.7 μg/L), Pb (5.85 μg/L), Ni (14.1 μg/L), Sb (0.170 μg/L), Sn (1.68 μg/L), and V (0.550 μg/L), while residents had elevated levels of Cr (2.05 μg/L), Mn (1.76 μg/L), and Co (0.360 μg/L). Sn, Sb, Pb, Co, and Ni were identified as candidate biomarkers tentatively associated with occupational exposure in baking settings. Cr was potentially indicative of exposure to feeding dust, while V and Mn showed preliminary associations with both baking and smelting activities. Employment duration (positive for Ni, Cd, and Pb), smoking status, gender, age, body mass index, and alcohol consumption jointly regulated concentrations of these urinary metal(loid)s. High non-carcinogenic risks were identified for Cu (95.5%), Pb (75.7%), Zn (45.0%), and Ni (25.7%) in workers, with Cu (50.5%) and Pb (35.4%) contributing most to hazard index variance. Monte Carlo simulation integrated with sensitivity analysis confirmed the robustness of the risk assessment outcomes and identified urinary metal(loid) concentration as the predominant driver of HI uncertainty. This study identifies candidate biomarkers tentatively associated with specific dismantling processes and reveals elevated non-carcinogenic risks in workers, providing a preliminary scientific basis for targeted occupational health protection in e-waste recycling.