Health risk assessment of heavy metals in agricultural soils and identification of main influencing factors in a typical industrial park in northwest China

The accumulation of heavy metals (HMs) in the soil poses a threat to human health. In this study, 62 pairs of topsoil and wheat grain samples were collected from a typical industrial park in northwest China, and the human health risks associated with cadmium (Cd), chromium (Cr), copper (Cu), mercury (Hg), nickel (Ni), lead (Pb) and zinc (Zn) were assessed through multiple exposure pathways. Meanwhile, the contribution of different environmental factors and their interactions were explored by using geodetector. Results showed that Cd concentration in the soil ranged from 0.307 to 2.491 mg kg(-1), with a median value of 0.588 mg kg(-1), and almost half of the samples exceeded the pollution threshold. In comparison, other elements in the soil were below their mandatory thresholds. However, it is noteworthy that in addition to the median Cd concentration in wheat grains of 0.062 mg kg(-1) (0.018-0.246 mg kg(-1)), the Pb concentration also reached 0.2 mg kg(-1) (0.1-0.7 mg kg(-1)), with a sample over-standard rate of 48.39%. In addition, the health risk assessment results showed that the average total hazard index (HIt) for adults and children was 1.22 and 1.53, and the total carcinogenic risk (TCRt) was 7.0 x 10(-4) and 2.32 x 10(-4), respectively, both above acceptable criteria. Dietary intake was the main route of exposure. Among various factors, distance from industrial enterprises, altitude, and soil pH, distance from major roads were the most influential contributors. Their interactions were more prominent than the effects of single factors and this synergy deserves attention. (C) 2020 Elsevier Ltd. All rights reserved.