Abstract

Road dust in areas contaminated by electronic waste (e-waste) processing activities can act as a sink for potentially toxic heavy metals and serve as a primary exposure pathway for nearby populations. This study investigates the concentrations of lead (Pb), chromium (Cr), cadmium (Cd) and arsenic (As) in road dust from an e-waste contaminated area in Thailand and is the first in the country to evaluate associated non-carcinogenic and carcinogenic health risks across the cool, dry and wet seasons. Road dust samples were collected and analysed using standardised protocol and standard analytical methods, respectively. Human health risks via unintentional dust ingestion were assessed for children and adults following United States Environmental Protection Agency (US EPA) guidelines. One-way analysis of variance (ANOVA) indicated no significant seasonal variation in metal concentrations (p = 0.06-0.985). Notably, the lowest dust contents of all four metals were observed during the wet season, coinciding with reduced e-waste recycling activity during the COVID-19 outbreak, suggesting a substantial influence of e-waste volume and recycling intensity on dust metal levels. Hazard quotient (HQ) and hazard index (HI) values for all heavy metals were below acceptable thresholds for both age groups, although consistently higher values were observed in children. Carcinogenic risk estimates for hexavalent chromium (Cr(VI)), Cd and inorganic arsenic (iAs) fell within negligible to acceptable ranges, with higher estimates observed in children across all seasons. Overall, the findings indicate limited health risks under current conditions, while emphasizing the importance of continued environmental monitoring in e-waste contaminated environments and sustained attention to potentially vulnerable populations.