Pollution Indices and Health Risk Assessment of Heavy Metal levels in Oryza Sativa (Rice) consumed in Southeastern, Nigeria.

The study assesses heavy metal concentrations [Lead (Pb), Cadmium (Cd), Zinc (Zn), Chromium (Cr), Copper (Cu), Nickel (Ni)] in rice grains from Southeastern Nigeria, comparing imported and locally cultivated varieties. Rice samples were procured, processed, and analyzed for heavy metals using atomic absorption spectrophotometry. Statistical analysis, USEPA models, and FAO/WHO standards were employed for data evaluation and human health risk assessment. Results indicated Cr and Cd concentrations below detectable levels (0.001 mg/kg), with 27% of Pb falling below 0.001 mg/kg. Concentrations ranged from 1.03–3.43 mg/kg for Cu, 0.28–3.36 mg/kg for Ni, 1.13–23.5 mg/kg for Zn, and 0.001–20.8 mg/kg for Pb. All samples met limits for Cu, Cd, Zn, and Cr, while 60% and 66% exceeded FAO/WHO standards for Ni and Pb, respectively. Estimated daily metal intake varied widely, and human health risk assessment revealed hazard quotients (HQ) below one for adults and above for children in all samples. Hazard indices surpassed one for both populations due to cumulative health risks from Ni, Pb, and Cu. Incremental lifetime cancer risk (ILCR) for Pb and Ni ranged from 1.2E-05 to 7.5E-06 and 1.5E-04 to 3.2E-04, respectively. Despite potential health risks, continuous monitoring of toxic metal concentrations in rice samples is crucial for averting adverse effects on consumers.