Heavy metal and metalloid contamination of rice and vegetables and their health risk in China

Objective To assess the heavy metal and metalloid pollution of the typical crops rice and vegetables in China and the related health risks, and to screen and identify concern areas, heavy metals and metalloids, and sensitive population.

Methods Based on the relevant literature from 2002 to 2020, geographic information system analysis and health risk assessment were used to analyze the excess rate of heavy metals and metalloids in crops, differences in spatial distribution, and health risk values.

Results The median concentrations of Pb, Cd, Hg and As in rice are 0.07, 0.06, 0.01 and 0.10 mg/kg, respectively, with excess rates ranking of As (22.45%) > Cd (17.57%) > Hg (14.63%) > Pb (14.49%). The median concentrations of Pb, Cd, Hg, Cr and As in vegetables are 0.06、0.02、0.002、0.09 and 0.03 mg/kg, respectively, with excess rates ranking of Pb (37.61%) > Cd (21.76%) > Cr (16.10%) > Hg (5.56%) > As (0.77%). The mass concentration of heavy metals and metalloids in crops showed spatial heterogeneity, with relatively high excess rates in Southern provinces such as Hunan, Yunnan, Guizhou, and Guangxi. The mean harm index(HI) value of non-carcinogenic risk caused by eating rice and vegetables in different populations is over 1, and the carcinogenic risk is at the level of 10^-4 through literatures. Both non-carcinogenic and carcinogenic risks of heavy metals and metalloids were higher in children than in adults.

Conclusion Heavy metals and metalloids in crops pose a threat to human health in China. In the future, more stringent controls on the heavy metals and metalloids in rice and vegetables should be implemented, especially in Hunan, Yunnan, and Guizhou provinces, and we should pay more attention to the health risks of heavy metals and metalloid s in children.