Pollution evaluation and dietary exposure risk assessment of heavy metals in rice from a lead-zinc ore mine

90 rice samples were collected from a Lead-zinc mine located in Guangdong province，the contents of cadmium（ Cd），chromium（ Cr），lead（ Pb），arsenic（ As）and zinc（ Zn）in rice were analyzed. The pollution situation was evaluated by single factor pollution index and N. L. Nemerow comprehensive pollution index，and the intake healthy risk of heavy metals from rice ingestion was assessed by a multimedia exposure assessment model（ the MMSOILS model）promoted by USEPA. The average concentrations of Cd，Cr，Pb，As and Zn in rice were 0.4098，0.4727，0.1746，0.0401，15.8100 mg/kg，respectively. Only the levels of Cd and Pb exceeded the standard，and the over standard rates were 83.33% and 31.11%，respectively. The average single factor pollution index of Cd，Cr，Pb，As were 2.0490，0.4727，0.8732 and 0.2006，respectively，suggesting the rice were polluted by Cd in some extent. Comprehensive pollution index indicated that 17.78% of the rice samples were uncontaminated，45.56% were slightly polluted，24.44% were moderate polluted，and 12.22% were heavily polluted. Among the study elements，only the daily intake dose of Cd and Cr exceeded the USEPA reference standard dose（ RfD），with hazard quotients （HQ）of 2.740 and 1.0533，respectively，indicating the local residents were experiencing certain Cd and Cr exposure risk from rice ingestion