Bioaccessibility and health risk assessment of arsenic in arsenic-enriched soils, Central India

Incidental soil ingestion is expected to be a significant exposure route to arsenic for children because of the potentially high arsenic contents found in certain soils. Therefore, it is prudent to get information on oral bioaccessibility of arsenic following incidental soil ingestion and its relevance in health risk assessment for future remediation strategies. Soil samples were collected from eight villages of Ambagarh Chauki block, Chhattisgarh, Central India. The soils from seven villages had total arsenic content more than the background level of 10 mg kg−1 (ranged from 16 to 417 mg kg−1), whereas the total arsenic content of soil from Hauditola was 7 mg kg−1. Bioaccessible arsenic assessed by the simplified bioaccessibility extraction test (SBET) ranged from 5.7 to 46.3%. Arsenic bioaccessibility was significantly influenced by clay content (R2=0.53, p<0.05, n=8), TOC (R2=0.50, p<0.05, n=8), Fe content (R2=0.47, p<0.05, n=8) and soil pH (R2=0.75, p<0.01, n=8). Risk assessment of the study sites showed that hazard index of arsenic under incidental soil ingestion was below 1 in all the study sites, except Kaudikasa. However, carcinogenic risk probability for arsenic to children from the villages Meregaon, Thailitola, Joratarai and Kaudikasa was below acceptable level (<1×10−4), suggesting potential health risk for children from these sites could not be overlooked. With high carcinogenic risk value (3.8E−05) and HI index (>1) for arsenic in soils of Kaudikasa, attention should be paid for development of remediation measure.

► Total arsenic content in soil varied from 7 to 417 mg kg−1.
► Bioaccessible arsenic of the study sites ranged from 5.7 to 46.3%.
► As-bioaccessibility was significantly influenced by clay content, TOC, Fe and pH.
► Hazard index of arsenic was below one in seven sites except Kaudikasa.
► Carcinogenic risks from four villages were under acceptable level.