Human exposure to polychlorinated alkanes (C8-36) in soil and dust from Nigerian e-waste sites: occurrence, homologue pattern and health risk assessment

Abstract

Electronic waste (e-waste) dismantling and dumpsite processes are recognized as significant sources of chlorinated paraffin (CP) exposure. This study aims to investigate the environmental occurrence and distribution of polychlorinated alkanes (PCAs-C_8-36), specifically in soil and outdoor dust samples collected from e-waste dumpsites and automobile dismantling and resale sites in Nigeria. The results revealed a widespread occurrence of PCAs across all sampled locations. For the PCAs homologue groups ∑PCAs-C_10-13, ∑PCAs-C_14-17, and ∑PCAs-C_18-20, the median concentrations were 1,150 ng/g dry weight (dw), 1,180 ng/g dw, and 370 ng/g dw in the dust samples, and 2,840 ng/g dw, 1,820 ng/g dw, and 830 ng/g dw in the soil samples, respectively. Notably, the homologue distribution patterns of PCAs-C_8-36 were similar in both dust and soil samples. However, PCAs-C_10-13 was found to be higher in the soil samples, likely due to the wet and/or dry deposition effect of the aerosols, given these chemicals' volatile nature and ease of atmospheric dispersion. Pearson correlation analysis further revealed a co-occurrence of contaminants in the soil samples, supporting the hypothesis that soil acts as a sink for persistent organic pollutants (POPs). Additionally, lower molecular weight polychlorinated biphenyls (PCBs) and organochlorine pesticides (OCPs) showed reduced correlation with the PCAs. Health risk assessments indicated that working on e-waste sites could potentially pose a risk to the workers' health. This study highlights the urgent need for mitigating occupational exposure to PCAs, especially in informal e-waste processing environments where personal protective measures are often lacking.