Appraisal of heavy metal(loid)s contamination in rice grain and associated health risks

The development of economy and society makes the heavy metal(loid)s pollution more serious and contamination of rice grains by heavy metal(loid)s is a worldwide problem. In order to appraise the health risks associated with heavy metal(loid)s (As, Cd, Co, Cr, Cu, Fe, Hg, Mn, Ni, Pb and Zn) in rice grains, we performed a meta-analysis based on the datasets collected from the literature (n = 248) between 2010 to 2023. The global mean values obtained for heavy metal(loid)s were in the following order: Fe (214.1µgg-1) > Zn (38µgg-1) > Mn (29.3µgg-1) > As (1.9µgg-1) > Cu (6.8µgg-1) > Cr (3.7µgg-1) > Pb (6.6µgg-1) > Ni (7.6µgg-1) > Co (1.0µgg-1) > Cd (0.20µgg-1) and Hg (0.01µgg-1). The relatively higher content of Pb, As, Cu, Hg and Zn was reported in China; Cr, Fe, Mn, Zn and Cu in Bangladesh; and Fe, Zn and Mn in Nigeria and India. The hazard quotient values of As were found greater than one for all the studied countries in both adults and children. These results suggest that contamination of rice grains with heavy metal(loid)s might lead different countries to establish strict legal guidelines and policies for preventing the heavy metal(loid)s contamination crop cultivation near contaminated areas.