Health risk assessment of heavy metal contamination in rice cultivation of Eastern India

The study describes the heavy metal content (Pb, Cd, As, Ni, Cu, and Zn) in irrigation water, soil, and rice plants in paddy fields of Sambalpur, Bargarh, and Subarnapur districts in Western Odisha, Eastern India. The heavy metals were analyzed by inductively coupled plasma optical emission spectroscopy. The soils in the experimental paddy fields had higher heavy metal contents than the soils in the nearby control field. Except for Cd, all heavy metal concentrations in soils were below the recommended limits of the national and international standards. All the heavy metal contents (except Pb and Cu) in the grain and straw were above the acceptable limit set by Indian standards. The relative heavy metal order for the soil-to-grain bioaccumulation factor was Zn > Ni > As > Pb > Cu > Cd. The bioaccumulation factor of all heavy metals (apart from Cd) was greater than 1, indicating that rice grain accumulates Zn, Ni, As, Pb, and Cu but absorbs only Cd. All heavy metals (except for Zn and Cu) had a health risk index value greater than 1, suggesting a potential threat to consumers through rice intake. Further, all of these metals (except Pb) have higher cancer risk values than the acceptable limit, indicating a possible cancer risk for consumers. Cd poses a significant risk, both non-carcinogenic and carcinogenic. Therefore, Cd exposure in the soil-rice system requires special consideration and effective regulation to ensure food safety in the study area.