Health Risk Assessment of Heavy Metals from Road Dust in Residential Areas near a Mining Area of Guangxi

Objective  To evaluate the health risks to adults and children caused by heavy metals in road dust in residential areas near a mining area of Nandan, Guangxi.

Method  Road dust samples (n=46) were collected in selected residential areas near a mining area in Nandan to evaluate levels of arsenic (As), cadmium (Cd), lead (Pb), stibium (Sb), and mercury (Hg). The cancer and non-cancer risks of heavy metals in road dust for local children and adults were estimated using United States Environmental Protection Agency (USEPA) health risk assessment model.

Result  The average levels of As, Cd, Pb, Sb, and Hg in road dust in residential areas near a mining area of Nandan were 1 332.81, 38.00, 650.88, 570.20, and 2.63 mg/kg, which were 99.5, 481.0, 31.8, 191.3, and 2.2 times of the soil background values of corresponding heavy metals in Guangxi, respectively. The heavy metals levels of all (100.0%) road dusts samples exceeded the national standard limits for As, Cd, and Sb; besides, the heavy metals levels of 55.6% and 77.8% of the samples exceeded the limits for Pb and Hg, respectively. By hand-mouth pathway, both non-cancer and cancer risks for children were higher than those for adults. The order of the total non-cancer risks of heavy metals from high to low was As > Sb > Pb > Cd > Hg, while that of the total cancer risks was As > Pb > Cd. The total non-cancer risk for adults and children were 11.2 and 65.4, and the total cancer risk were 4.83×10^-3 and 2.82×10^-2, respectively. The non-caner risks of As and Sb through hand-mouth ingestion for adults were 7.51 and 2.41 respectively; the non-caner risks for As, Sb, and Pb through hand-mouth ingestion for children were 44.90, 14.40, and 1.84, respectively; all exceeded the acceptable non-cancer risk level (> 1). The cancer risks of As and Cd through hand-mouth ingestion and dermal exposure in adults and children all exceeded the acceptable carcinogenic risk level (10^-4).

Conclusion  The contamination of heavy metals in road dust in the study area is severe. Attention should be paid to the health risks caused by heavy metals to the residents.