Zinc (Zn) deficiency is a worldwide problem among humans, especially among those taking cereals as staple food. Soil Zn application is a feasible approach to quickly and effectively increase grain Zn concentration of wheat and maize, thereby benefit human health. However, the effect of continuous soil Zn application on the health risk of heavy metals is still unclear.

To quantify the effects of continuous soil Zn application on the potential health benefit and health risk of heavy metals, a field experiment with six Zn rates (0, 2.3, 5.7, 11.4, 22.7 and 34.1 kg Zn ha^-1) was conducted in a winter wheat-summer maize rotation system from 2009 in Quzhou county, Hebei province. The health benefit (disability-adjusted life years , DALYs saved) of Zn and the human risk of heavy metals in wheat and maize grains were quantitatively assessed after 8 years’ soil Zn application.

Results showed that both grain Zn concentration and Zn bioavailability of wheat and maize were significantly increased as Zn rate increased. Meanwhile, the wheat and maize grain in the treatments which had received fertilizer Zn application have decreased by 8%-28% of current health burden in optimistic scenario and 3%-9% in pessimistic scenario. The health risk index (HRI) of Zn was significantly increased whereas that of arsenic (As) and manganese (Mn) were decreased in response to the increase of Zn concentration in wheat and maize grains. The HRI of lead (Pb) and cadmium (Cd) were significantly increased in wheat grain while decreased in maize grain. The hazard indexes of wheat and maize were not affected by Zn application rates. The target cancer risk indexes of As in wheat and maize grain were significantly decreased with the increase of Zn rates.

In conclusion, Zn application can benefit human health without increasing the risk of heavy metals. This study comprehensively evaluated the effect of Zn fertilizer application on human health and highlighted its particular importance in agricultural production.