Pilot Multi-Matrix Biomonitoring of Mixed Mercury Exposure Pathways Among E-Waste Dismantling Workers in South China

Informal electronic-waste (e-waste) dismantling can mobilize mercury (Hg) from Hg-containing components and contaminated dust, while local diet can contribute methylmercury (MeHg), creating a mixed environmental exposure setting for human biomonitoring. This pilot study integrated paired biomarkers, local foods, work and indoor dust, Hg speciation and hair Hg isotope signatures among 18 e-waste dismantling workers in Qingyuan, South China. Total Hg (THg), MeHg and inorganic Hg (IHg) were measured in hair, blood and foods; urine and dust were analyzed for THg; and hair δ²⁰²Hg, Δ¹⁹⁹Hg and Δ²⁰¹Hg were determined. Median THg was 403 μg/kg in hair, 1.60 μg/L in blood and 0.438 μg/L in urine. Fish showed the highest food THg, whereas work and indoor dust had the highest matrix concentrations. Hair was MeHg-dominant but contained substantial IHg, and Δ¹⁹⁹Hg values were positive but modest. The integrated patterns support mixed dietary MeHg and non-dietary IHg contributions and identify exposure-pathway priorities for future biomonitoring and source-focused studies.