Geographical variation, accumulation risk, and risk management of rice heavy metal(loid) contamination in China

Grain is a crucial source of human nutrition, and its quality is linked to the health of populations and sustainable development of economies and societies worldwide. However, at national and global scales, information on rice quality and safety is relatively limited. To address this knowledge gap, this study constructed a high-resolution nationwide database of heavy metal (HM) pollution in rice across major grain-producing areas in China based on extensive field survey data from 2018 to 2020 (3198 samples). The database was used to evaluate the pollution status, identify hotspot distribution areas, and supplement existing knowledge gaps. The results revealed that the mean concentrations of HM in rice exceeded the standard value in varying degrees across provinces, with Cd, Pb, and Hg being the most prominent pollutants, showing exceedance rates of 18.7 %, 6.4 %, and 4.2 % respectively. Hotspot analysis indicated that the spatial aggregation of HM contaminations was significantly influenced by human activities, with pollution primarily concentrated in industrial and mining clusters or economically developed regions. Moreover, the consumption of contaminated rice poses both carcinogenic risks (eg., Cd, As, or Ni) and non-carcinogenic hazards to human health. These findings highlight the urgent need for action from the government to implement green restoration strategies for HM-contaminated rice.