Abstract: In order to evaluate the risks of heavy metal pollution in paddy soils with high geological background of transportation and deposition, we measured the contents of cadmium (Cd), copper (Cu),  lead (Pb) and zinc (Zn) in 31 pairs of rhizosphere soil and rice samples collected in DoumenXinhui districts of Guangdong Province. We applied influence index of comprehensive quality (IICQ) and health risk assessment models to assess soil heavy metal pollution and its human health risks. The results showed that the proportions of soil samples at clean, sub-healthy, moderately polluted and heavily polluted status were 22.6%, 41.9%, 3.2% and 32.3%, respectively. The non-carcinogenic risks of Cd, Cu, Pb and Zn in rice were relatively low, with hazard quotient (HQ) of all the four kinds of metals being less than 1. Among the four metals, Cd had the highest noncarcinogenic risk. The hazard index (HI) of four metals was about 1. Carcinogenic risk (CR) index of rice Cd was higher than 10^-4, suggesting a high carcinogenic risk. The CR value ranged between 10^-6 and 10^-4 for rice Pb, indicating that the carcinogenic risk was at an acceptable range. Children’s noncarcinogenic risk and carcinogenic risk were higher than adults. Our findings provide data support for the rice safe production and soil pollution risk control in the areas with high geological background of transportation and deposition.

Key words: high geological background of transportation and deposition, heavy metal, influence index of comprehensive quality (IICQ), health risk.