Mercury contents in rice and potential health risks across China

Rice samples were collected at 560 sites in 15 provinces across China in areas without known point mercury (Hg) sources. Total mercury (THg) and methylmercury (MeHg) concentrations were analyzed in these rice samples for risk assessment. Relatively low THg and MeHg concentrations were found in the majority of the white rice samples with an overall mean of 4.74 (1.06-22.7) mu g kg(-1) and 0.682 (0.03-8.71) mu g kg(-1), respectively. The means (range of) THg concentration of rice in each geographical region were 5.23 (1.07-19.5) mu g kg(-1), 5.14 (1.06-17.2) mu g kg(-1), 4.45 (1.41-17.2) mu g kg(-1), 4.20 (1.48-19.4) mu g kg(-1), 3.49 (1.49-10.7) mu g kg(-1), and 4.53 (1.30-19.4) mu g kg(-1) in east, centre, south, southwest, northwest and northeast, China, respectively, and the corresponding values for MeHg concentrations were 0.898 (0.127-8.35) mu g kg(-1), 0.603 (0.207-2.48) mu g kg(-1), 0.516 (0.032-1.50) mu g kg(-1), 0.615 (0.050-5.03) mu g kg(-1), 0.704 (0.148-2.41) mu g kg(-1) and 0.565 (0.035-8.71) mu g kg(-1), respectively. Hg contents in rice across China were found to be at background levels. Both the probable daily intakes (PDIs) of inorganic Hg (IHg) and MeHg from rice consumption showed low risks for general population in the investigated regions.