Persistent toxic elements in soil–water–food systems: food safety, implications, biomonitoring insights, and cumulative toxicological risk assessment

Persistent toxic elements (PTEs), including arsenic, cadmium, lead, and mercury, pose persistent challenges to environmental sustainability, food safety, and public health due to their mobility, bioaccumulation potential, and long-term toxicity across soil-water-food systems. This review provides an ordered critical scoping synthesis of the current evidence on the environmental fate, food-chain transfer, dietary exposure, biomonitoring applications, mechanistic toxicology and cumulative risk assessment of priority PTEs in agricultural and aquatic food systems. Emphasis is given to the transfer of environmental contamination into biologically relevant exposure via crop uptake, contaminated water, livestock transfer and aquatic bioaccumulation. The review critically discusses limitations of conventional risk assessment frameworks of single contaminants, emphasizing the importance of bioavailability, mixture toxicity, chronic multi-pathway exposure, and population vulnerability in determining real-world risk. Biomarker-based approaches are explored for their utility in linking environmental contamination with internal exposure and early biological response. Mechanistic toxicology is considered in the context of food safety and cumulative risk interpretation. Major knowledge gaps remain in integrating environmental monitoring, biomonitoring, dietary exposure assessment, and mixture-based risk characterization within operational surveillance systems. Advancing toward biologically informed, exposure-realistic, and integrated risk assessment frameworks will be essential for improving food safety management and long-term resilience of contaminated food production systems.