The geogenic cadmium and potential health risk in the Three Gorges region, Southwest China

The geogenic Cd related to black shale weathering has produced Cd enrichment in local surface environment of the three Gorges region, China. In order to investigate the Cd distribution and health risk, the local rock, soil,... [ view full abstract ]

The geogenic Cd related to black shale weathering has produced Cd enrichment in local surface environment of the three Gorges region, China. In order to investigate the Cd distribution and health risk, the local rock, soil, food crop and population urine samples were monitored. Elevated Cd concentrations were observed in local arable soils (0.42-42 mg/kg) and natural soils (0.12-8.5 mg/kg), corresponding to high amounts of Cd (0.22–42 mg/kg) in local black shale. The enrichment factor plots illustrated that the majority of soil samples had EF values of <5, pointing to geogenic origin of Cd, whereas some arable soils had EF values >5, pointing to an additional anthropogenic input of Cd. The average Cd contents were 0.68 mg/kg (fresh weight) in local vegetables. The elevated bio-accumulation factors for Cd were due to its high potential bioavailability in soils, and leaf vegetables tend to accumulate more Cd than the other crops. The calculated health risk index has higher values (4.62) for Cd than for other metals (< 1), suggesting that Cd represents a significant potential risk for the local population. The urinary Cd levels (mean at 3.92 μg/L for male and 4.85 μg/L for female) of local inhabitants were significantly higher than those from control area (mean at 0.8 μg/L for male and 0.42 μg/L for female). The findings show that naturally-occurring Cd in local soils is taken up appreciably by food crops, and can pose potential health risk to public, through dietary vegetable ingestion exposure of Cd.