Health risk assessment of heavy metals of street dust in Beijing

Street dust is an important environmental pollutant in urban area.Long-term exposure to the dust environment would cause chronic damage through ways of inhalation,ingestion,and dermal taken.In order to evaluate the potential health risk of street dust in Beijing,an extensive survey was conducted in the urban areas within the Sixth-Ring Road.Totally 225 dust samples were collected from the street surfaces in September 2009 and their concentrations of Cd,Cr,Cu,Mn,Ni,and Pb were determined.Human health risk assessment method established by U.S.EPA was used to evaluate the potential health risk of those heavy metals in the street dust.Except for Mn and Ni,the average heavy metal concentrations in the street dust were all higher than the background values of Beijing,where Cr was slightly higher,Cu and Pb were 2~3 times higher,and Cd was 5 times higher than the background values.The way of chronic daily average exposure was ingestion dermal taken inhalation.The non-cancer risk of exposure was CrMnPbCuNiCd for adult and Cr PbMn CuNiCd for children,while the cancer risk of exposure was CrNiCd.All the risks were lower than the average risk thresholds of the heavy metals,and would therefore not cause carcinogenic health hazard to human body.Generally,the most potentially harmful heavy metals in Beijing urban area were Cr and Pb.Moreover,a comparison among the 14 districts of Beijing with the non-cancer risk for children showed that downtown expanding urban area developing urban area,indicating significant relationship with district function.The health risks of Cu,Ni,and Pb were correlated with population density and the proportion of built-up area.Therefore,proper measures should be taken for the dust risk management in terms of human activities.