Gastric bioaccessibility and human health risks associated with soil metal exposure via ingestion at an E-waste recycling site in Kumasi, Ghana

Over 1000 people make a living by processing electronic and electrical waste (E-waste) and scrap metals for the recovery of valuable metals and integrated circuits at Dagomba Line, Kumasi, Ghana. The processing includes activities such as dismantling, open burning and open dumping of E-waste which can potentially release toxic metals into the environment and thus impact the health of recyclers and nearby residents. This study investigated the distribution of toxic metals (As, Cd, Cr, Cu, Hg, Ni, Pb, Sb and Zn) in surface soils at the E-waste recycling sites and determined the associated human health risk via ingestion incorporating bioaccessibility measurements. Metal concentrations in the activity sites were highly elevated, significantly higher than those in the surrounding area and exceeded international soil quality guidelines such as the Canadian soil quality guidelines for residential land use and the Dutch Intervention Value. Bioaccessibility was high for Pb (70.8%), Cd (64.1%), Cu (62.3%) and Ni (53.6%) which could be credited to the existence of oxidized species as a result of the E-waste burning. Non-carcinogenic effects were unacceptably high (hazard indices > 1) at 14 out of 31 sites, and the cancer risk for arsenic for adult workers was greater than 1 x 10(-5) at five of the sampling sites.