Health risk assessment of metal contamination in Malaysian rice (Oryza sativa): The impact of parboiling on toxic metal reduction prior to cooking

Metal contamination in rice grains is a critical global issue, posing serious health risks and affecting food safety, especially in countries like Malaysia where rice is a staple food. This study aimed to assess the effectiveness of various cooking treatments, with a focus on parboiling before absorption cooking (PBA), in reducing metal contamination in Malaysian rice. Metal levels were measured using tandem inductively coupled plasma mass spectrometry (ICP-MS/MS), and health risks were assessed following USEPA guidelines. Parboiling before absorption cooking was found to eliminate 77.9% of toxic metals and 68.4% of essential metals while keeping arsenic (As), cadmium (Cd) and lead (Pb) concentrations below permissible limits. Deterministic health risk assessment indicated that PBA reduced hazard index by 84.5% and lifetime carcinogenic risk (LCR) from As exposure by 88.9%. Hazard quotient for nickel (Ni) and zinc (Zn) remained acceptable for all age groups except for As in children, where LCR exceeded permissible limits. Monte Carlo simulations revealed that over 95% of individuals across age groups faced unacceptable non-carcinogenic and carcinogenic risks from As exposure, regardless of cooking method. In conclusion, PBA effectively lowered metal concentrations and health risks, especially for toxic metals in rice. Future studies could enhance risk assessment accuracy by analysing metal bioavailability and speciation of metals particularly As.