Heavy Metals in Smoked Fish: A Comprehensive Review of Nutritional Implications, Health Impacts, and Public Health Challenges in Nigeria

Background Smoked fish is a vital protein source and livelihood in Nigeria, but traditional smoking may introduce toxic heavy metals, creating public health concerns. Objective This review synthesizes Nigerian literature on heavy metal contamination in smoked fish, examining smoking processes, nutritional implications, health risks, and public health challenges, including occupational exposure of processors. Methods A systematic search of PubMed, Scopus, ScienceDirect, Google Scholar, and ResearchGate was conducted for studies published between 2015–2025 following PRISMA guidelines. Included studies reported quantitative data on heavy metal concentrations in Nigerian smoked fish. Data on metal levels, health risk indices (THQ, HI, cancer risk), nutritional parameters, and smoking methods were extracted and synthesized thematically. Results Studies across Ondo, Ogun, Lagos, Anambra, Borno, and the Niger Delta consistently report elevated lead, cadmium, chromium, and arsenic in smoked fish, frequently exceeding regulatory limits. Traditional drum-smoking yields higher contamination than improved kilns. Smoked fish retains nutritional value, creating a risk-benefit dilemma. Health risk assessments reveal non-carcinogenic effects (HI > 1) and unacceptable cancer risks from chromium. Children are most vulnerable. A critical gap is the complete absence of research on occupational exposure of fish smokers. Conclusion Heavy metal contamination causes significant risks to consumers while processors face unstudied occupational hazards. Addressing this requires improved smoking technologies, national surveillance, occupational health integration, and community education.