Assessment of heavy metal(loid)s contamination risk and grain nutritional quality in organic waste-amended soil.

Studies that evaluate the human health risk of heavy metal(loid)s pollution have not been widely performed for organic waste-amended soils on the Loess Plateau of China. With this respect, we conducted a 3-year field trial to estimate the heavy metal(loid)s contamination of soil and maize, the resultant nutritional quality of maize grains and the health risk under treatments of conventional fertilizer (CF), traditional Chinese medicine residue (TCMR) and sheep manure (SM). We found that protein, amino acids and lysine in maize grains were increased by 12.3, 11.3 and 5.88 % under TCMR treatments relative to SM application, respectively. Meanwhile, this treatment reduced the levels of Cr, Pb, Cd, As and Hg in soil and maize grains. All fertilization regimens resulted in greater health risks for children, with HI values ranging from 1.06 to 1.52 and CR levels for Cr and As being ﹥1.0 × 10-4, especially higher in SM treatments. This presented the beneficial effect of TCMR than SM. The further investigated of toxic metal(loid)s level in SM and its application risks, based on meta-analysis and Monte Carlo simulation, indicated Cd, Hg and Pb were the most cautionary heavy metal(loid)s and contamination risk were greater on the southwest regions of China.