HEALTH RISK IMPLICATIONS OF HEAVY METALS INTRODUCED DURING FOOD GRINDING

Food processing methods, particularly mechanical grinding, have been identified as potential sources of heavy metal contamination in daily diets. This study assessed the concentrations and health risks of heavy metals introduced into common Nigerian food items (tomato, pepper, melon, beans, groundnut, white and yellow corn, and crayfish) during grinding with various equipment types including blenders, milling machines, hand-crank grinders, mortars, and grinding stones. Heavy metals (Fe, Mn, Zn, Ni, Cd, and Pb) were analyzed using Atomic Absorption Spectrophotometry (AAS), and potential health risks were evaluated using Estimated Daily Intake (EDI) and Target Hazard Quotient (THQ) models. Results revealed elevated levels of essential metals such as Fe, Mn, and Zn, with concentrations highest in foods ground with older milling machines and mechanical grinders, reflecting increased leaching due to metallic wear. Toxic metals (Pb and Cd) were mostly below detection limits, indicating minimal immediate toxicity but potential for chronic accumulation. Fe showed the highest EDI (up to 5.35 mg/kg/day in hand-crank grinder samples), while THQ values exceeded 1.0 in several processed beans samples, suggesting possible non-carcinogenic risk upon prolonged exposure. Traditional grinding methods (mortar and pestle) exhibited significantly lower contamination levels compared to mechanical ones. These findings highlight that metal leaching from food processing equipment constitutes a significant but often overlooked route of dietary exposure to heavy metals in Nigeria.