Heavy Metal Toxicity and Contamination of Fishes in Port Harcourt Creeks: A Systematic Review of Evidence Integration of Lead, Chromium, and Cadmium Exposure, Impact, and Health Risks
Ibioku Elekima *
Department of Clinical Chemistry, Faculty of Medical Laboratory Science, Rivers State University, Port Harcourt, Nigeria.
Ajuka Ogechi Ada
Department of Clinical Chemistry, Faculty of Medical Laboratory Science, Rivers State University, Port Harcourt, Nigeria.
Monle Bagia
Department of Clinical Chemistry, Faculty of Medical Laboratory Science, Rivers State University, Port Harcourt, Nigeria.
Sharon Ureh Odu
Department of Clinical Chemistry, Faculty of Medical Laboratory Science, Rivers State University, Port Harcourt, Nigeria.
*Author to whom correspondence should be addressed.
Abstract
Background: Port Harcourt’s creek systems support fisheries while receiving domestic sewage, industrial effluent, and petroleum-related waste. Lead, chromium, and cadmium are persistent contaminants that can accumulate in fish tissues and create ecological and dietary concerns. This review synthesised evidence on their occurrence and toxicological effects in fish from Port Harcourt and Rivers State waterways.
Objective: To systematically review published evidence on the toxicological effects of lead, chromium, and cadmium on fish in Port Harcourt creeks, Nigeria, and to identify existing research and policy gaps.
Methods: A systematic search of electronic databases, including Google Scholar, the Cochrane Library, BIOSIS, and PubMed, was conducted using predefined search strings. Studies published between January 2015 and December 2025 were included if they reported toxicological outcomes of lead, chromium, or cadmium in fish species from Port Harcourt or Rivers State waterways. Methodological quality was assessed using the Critical Appraisal Skills Programme (CASP) checklist for environmental studies.
Results: A total of 37 studies met the final inclusion criteria. All three metals were consistently detected in fish tissues across multiple Port Harcourt creek systems, with liver and kidney accumulating higher concentrations than muscle tissue. Detected lead concentrations in fish muscle ranged from 0.31 to 5.31 mg/kg, cadmium from 0.008 to 1.31 mg/kg, and chromium from 2.08 to 9.01 mg/kg, all of which exceeded permissible limits commonly applied in comparable Niger Delta studies (0.3, 0.05, and 0.1 mg/kg, respectively). Dose-dependent histopathological lesions, including cellular degeneration and necrosis, were documented following cadmium and chromium exposure. Quantitative risk assessments confirmed both carcinogenic and non-carcinogenic health risks among regular consumers of fish from affected water bodies.
Conclusion: Lead, chromium, and cadmium represent a serious public health threat in Port Harcourt creek communities. Comprehensive biomonitoring, stronger regulatory frameworks, and routine aquatic toxicological monitoring are urgently needed to protect communities that depend on locally sourced fish.
Keywords: Heavy metals, lead, chromium, cadmium, fish bioaccumulation, histopathology, Port Harcourt creeks, seafood safety, human health risk