Health risk assessment of Cd pollution in irrigated paddy field system: A field investigation in Hunan Province, China

Abstract

Paddy crops cadmium (Cd) pollution has received widespread attention. Here, we assessed levels of Cd and organic matter fractions in sediments and paddy system of 19 paddy fields that were located 20 km away from an irrigation water source in central Hunan Province, China, to determine pollution risks of Cd to human health. With the exception of a single study site, levels of Cd in irrigation water met national irrigation water quality standards (GB5084-2005). In contrast, average Cd content in paddy soil and brown rice (0.625 and 0.567 mg kg−1, respectively) was 1.6 and 2.8 times higher than levels permitted by national standards for soils (GB15618-2018) and food safety (GB2762-2017), respectively. Dominant speciated Cd in sediments included extractable, oxidizable, and reducible Cd that accounted for 84.96% of total sediment Cd content. The average carbon content of humus was 18.906 g kg−1. Fulvic acid content of humus was positively correlated with reducible and oxidizable Cd content. Cd pollution in paddy fields was great and risks of Cd in brown rice to human health were high. Risk assessment can provide reasonable suggestions for human diets and provide new ideas for the prevention and control of soil Cd pollution.