Heavy metals and associated health risk of wheat grain in a traditional cultivation area of Baoji, Shaanxi, China

As a staple food for people worldwide, wheat is one of the major exposure pathways for heavy metals (HMs). Therefore, the safety of the wheat grain directly affects food security and human health. Long-term agricultural activities are sources of heavy metal pollution in farmland ecosystems. This study assessed the pollution situation of HMs in wheat grain from the major wheat-cultivation areas of Baoji, a typical agricultural area in Shaanxi, to assess the dietary health risks caused by consuming wheat grains and to prevent food pollution. The results showed that the mean grain concentration of Cr, Ni, Cu, Zn, Cd and Pb were 0.11, 0.09, 4.41, 26.79, 0.01 and 0.03 mg/kg, respectively. These values were all remarkably lower than the tolerance limits of the Chinese food hygiene standard (GB2762-2017). According to the metal pollution index (MPI) analysis, wheat grain consumption poses no direct threat to human health. The health risk assessment showed that there was a noncarcinogenic risk to adults and children for wheat consumed in the study area. In the study area, no carcinogenic risk was manifested. Principal component analysis (PCA) indicated that the source of Ni was different from that of the other tested HMs and was mainly from industry, where as the others were mainly derived from agricultural activities. Therefore, more attention should be paid to Cu and Zn input through agricultural activities in fields to further prevent the accumulation of these HMs in wheat grains and their related human health risks.