Risk Assessment of Heavy Metal Contamination in Processed Fish Products from Lagos Markets

Heavy metal contamination in fish products poses significant health risks to consumers, particularly in coastal urban markets like Lagos where industrial, agricultural, and domestic pollution affect aquatic environments. This study conducts a food safety risk assessment for lead, cadmium, mercury, and arsenic in processed fish products (smoked mackerel, canned sardines, and dried stockfish) sampled from 25 vendors in four major Lagos markets. Metal concentrations were determined by atomic absorption spectrometry after wet acid digestion. Exposure assessment was conducted using per capita fish consumption data from the National Nutrition Survey combined with the measured metal concentrations. Risk characterisation was performed using hazard quotient and incremental lifetime cancer risk calculations. Results showed that lead concentrations in smoked mackerel exceeded the European Union maximum residue limit in 35 percent of samples, and cadmium exceeded limits in 28 percent of canned sardine samples. Hazard quotient calculations indicated that regular consumers of contaminated smoked mackerel faced hazard quotients above 1.0 for lead, indicating non-carcinogenic health risk. Incremental lifetime cancer risk for arsenic was within acceptable margins across all products. The study draws on recent heavy metal food safety literature for West African coastal cities. Findings provide an evidence base for tightening food safety regulation and monitoring of processed fish products in Lagos. Keywords: heavy metals, fish products, risk assessment, food safety, Lagos