Health risk assessment of soil heavy metals in housing units built on brownfields in a city in China

Purpose: The present paper concerns the patterns of heavy metals (As, Hg, Pb, Cd, Ni, Zn, Cr, and Cu) in surface soil of residential areas located on derelict brownfields in a city in China and the health risks to the residents. Materials and methods: Forty-one surface soil samples were collected from 9 housing units built on different brownfields in a city of Henan Province in China, and the concentrations of heavy metals were measured. Based on the health risk models recommended by the US Environmental Protection Agency (US EPA), carcinogenic and non-carcinogenic health risks of soil heavy metals were assessed. Results and discussion: Compared with the original brownfields, soil heavy metal contents and their health risks in housing units built on brownfields have significantly decreased. The contents and health risks of heavy metals in these housing units are all higher than those in non-brownfield housing units. The result of health risk assessment indicates that there are no non-carcinogenic risks and slight carcinogenic risks for the residents in these housing units. The contribution of hazard quotient caused by arsenic (HQ_As) to hazard index (HI) is approximately 53%, and the contribution of cancer risk caused by arsenic (CR_AS) to total carcinogenic risk (TCR) is approximately 80%. Conclusions: The obtained results have confirmed the environmental effects of brownfields and that soil remediation is an essential step for the redevelopment of brownfields. Arsenic is the crucial heavy metal for carcinogenic and non-carcinogenic risk in the housing units of the city, and the highest levels of non-carcinogenic and carcinogenic risks are associated with the route of ingestion of soil for all heavy metals.