Distribution of metals in urban dusts of Hefei and health risk assessment

This study focused on the characterization and the health risk assessment of heavy metals in the dust of Hefei City,China.Samples were collected from fifty two sampling points covering six land-use types.Most of the sites were impervious ground such as residential,commercial,industrial,educational and traffic areas,as well as public landscapes and city squares.Concentrations of Zn,Pb,Cu,Cd and Cr were measured to investigate their distribution and evaluate their risk to human health.The US EPA Health Risk Assessment Model was employed to evaluate the carcinogenic and non-carcinogenic risks of heavy metals to child and adult,respectively.The results showed that concentrations of Cd and Zn were 46 and 37 times higher than soil background values,respectively.The concentrations of Cu and Pb were 3-5 times,and Cr concentration was 1.5 times higher than the soil background values of Anhui Province.The carcinogenic risk indexes of Cr and Cd were 3.22×10-7 and 2.26×10-9,respectively,which were lower than the soil management standard of the US EPA,i.e.1.0×10-6.The total non-carcinogenic hazard index of the five metals for adults was only 0.212,but for children it reached to 1.259 and exceeded the safety threshold value(1.0),suggesting that the adverse health impact on children exposure to metals in urban dusts were relatively serious in Hefei.The ingestion of dust particles was the major exposure pathway for health risk.The orders of non-carcinogenic hazard indexes of land-use types and heavy metals were industrial areapublic landscapes and city squarescommercial areaeducational arearesidential areatraffic area,and PbCrZnCdCu,respectively.