Toxicological Evaluation of Pb, Cd, As, and Hg in Blue Crab from Oil-Polluted Creeks in the Niger Delta

This study examined the concentrations and toxicological risks of four priority heavy metals lead (Pb), cadmium (Cd), arsenic (As), and mercury (Hg) in blue crabs (Callinectes sapidus) collected from oil-affected creeks in Rivers State, Nigeria. A total of 90 crabs were gathered from Bodo, Ataba, and Okpoka creeks, and metal analysis was conducted using Microwave Plasma Atomic Emission Spectroscopy (MP-AES 4200) after acid digestion. One-way ANOVA revealed significant site-related variations for all metals (p < 0.001) and significant gender effects for Pb and Hg (p < 0.05), with Tukey’s post-hoc tests indicating that crabs from Ataba and Bodo contained significantly higher concentrations than those from Okpoka (p < 0.05). Human health risk indices, including Estimated Daily Intake (EDI), Target Hazard Quotient (THQ), Hazard Index (HI), and Lifetime Cancer Risk (LCR), were calculated for both adult and child consumers based on mean metal concentrations. Results indicated that mean concentrations of Pb, Cd, As, and Hg in crab tissues exceeded permissible limits set by the World Health Organisation and the Food and Agriculture Organisation (WHO/FAO), with the highest values recorded in Ataba and Bodo creeks. THQ and HI values for Pb and As surpassed the acceptable threshold of 1 in both adult and child groups, signalling potential non-carcinogenic health risks. LCR values for As and Pb also exceeded the United States Environmental Protection Agency (USEPA) acceptable range (10⁻⁶–10⁻⁴), suggesting carcinogenic potential with prolonged exposure. These findings highlight critical environmental and public health concerns linked to seafood consumption from oil-contaminated ecosystems in the Niger Delta and underscore the need for continuous ecological monitoring, stricter seafood safety regulations, and targeted community health awareness programmes.