TOXICOKINETIC ASSESSMENT OF HEAVY METAL BIOACCUMULATION IN THE FOOD CHAIN AND ASSOCIATED HUMAN HEALTH RISKS IN AGRICULTURAL REGIONS OF PAKISTAN

Abstract

Heavy metal contamination in agricultural systems poses a significant threat to food safety and public health, particularly in developing countries such as Pakistan. This study aimed to assess the toxicokinetics of heavy metal bioaccumulation in the food chain and evaluate associated human health risks in selected agricultural regions. A cross-sectional analytical design was employed, involving the collection of 150 environmental samples (soil, irrigation water, and crops) and dietary data from 120 participants. Concentrations of cadmium (Cd), lead (Pb), arsenic (As), mercury (Hg), and nickel (Ni) were determined using Atomic Absorption Spectrophotometry. Bioaccumulation and transfer factors were calculated to evaluate metal movement across the soil–plant continuum, while Estimated Daily Intake (EDI), Target Hazard Quotient (THQ), Hazard Index (HI), and carcinogenic risk (CR) were used to assess human health risks.The results revealed that heavy metal concentrations in soil, water, and crops exceeded permissible limits, with significant bioaccumulation observed in edible plant tissues. Strong positive correlations between soil and crop metal concentrations confirmed the role of environmental contamination in food chain transfer. Toxicokinetic-based exposure assessment indicated that THQ values for Cd, Pb, As, and Ni exceeded safe thresholds, while the overall HI suggested substantial cumulative risk. Carcinogenic risk values for Cd and As were significantly above acceptable levels, indicating potential long-term cancer risks.The study concludes that heavy metal contamination in agricultural systems of Pakistan represents a serious public health concern, driven by anthropogenic activities and inadequate environmental management. The integration of toxicokinetic assessment with environmental and dietary analysis provides a comprehensive framework for evaluating exposure and risk. Immediate interventions, including improved wastewater management, regular monitoring, and policy enforcement, are essential to mitigate contamination and protect human health.