A total of 92 corn grain samples, around the Pb-Zn mining area in Southwest China, were collected to evaluate the contamination and health risk of heavy metals. Heavy metals including Pb, Zn, Cd, Cr, and Ni in samples were analyzed. A single factor pollution index and comprehensive pollution index were calculated to assess the quality of corn grains. The potential health risks to adults and children due to the intake of these heavy metals through consumption of crops were evaluated using the health risk index. The results showed that the average contents of Pb, Zn, Cd, Cr, and Ni in corn grains were 0.30, 23.75, 0.21, 1.33, and 1.15 mg ·kg-1, respectively, Among the metals, the content of Zn, Pb, Cd, Cr, and Ni exceeded the national food hygiene standards. The Nemero index of Pb, Cd, Cr, and Ni ranged from 4.32 to 9.07, indicating an extremely high level, whereas the contamination of Zn reached an alarming level. The assessment results of the comprehensive health risk index for the corn grains indicated that the contamination of heavy metals poses health risks to adults and children by food ingestion; moreover, the children were more sensitive to various heavy metals than the adults. Principle component analysis revealed that the first main component dominated the sources of Pb, Cd, Cr, and Ni, while the second main component, Zn, might have originated from sources different from the other heavy metals. Positive correlations were not observed between the heavy metals in corns and soils.
Keywords: corn grains; heavy metal; mining area; principal component analysis; risk assessment.