Assessment of Heavy Metal Contamination and Health Risks in Crabs (Scylla senrata) from Oil and Non-Oil Producing Communities in Rivers State, Nigeria

Abstract

Heavy metal contamination in aquatic environments poses significant risks to public health, particularly in regions affected by industrial activities such as oil exploration. These contaminants can accumulate in marine organisms, posing risks to both ecosystems and human health through dietary exposure. The study investigates the health risks associated with heavy metal contamination in Scylla senrata harvested from Abonnema (non-oil producing community, NOPC) and Kula (oil producing community, OPC) in the Niger Delta region, Nigeria, at both low and high tides. The metals analyzed include iron (Fe), lead (Pb), nickel (Ni), manganese (Mn), zinc (Zn), copper (Cu), cadmium (Cd), and chromium (Cr). The analyses were conducted using flame atomic absorption spectrophotometry. Data were analyzed using SPSS software (version 21.0). The results showed significant variation in metal concentrations. Results showed elevated levels of Fe (94.7–146.8 mg/kg), Pb (8.3–38.28 mg/kg), Ni (3.62–6.45 mg/kg), Mn (42.79–71.43 mg/kg), Cu (18.5–27.95 mg/kg), and Cd (1.25–2.00 mg/kg) above WHO/FEPA (2003) limits, particularly in Kula. Chromium (Cr) levels were relatively lower, with concentrations ranging from 0.21 to 0.28 mg/kg at low tide and <0.001 mg/kg at high tide. In addition, zinc (Zn) concentrations remained within the permissible limit. The Estimated Daily Intake (EDI) and Target Hazard Quotient (THQ) calculations indicated that the concentrations of these metals are within safe limits for human consumption, with none of the THQ values exceeding the threshold of 1.0. In conclusion, these findings suggest that while anthropogenic activities, particularly oil exploration, contribute to metal contamination, the consumption of these crabs poses minimal health risk based on current metal exposure levels. Further research and continuous monitoring is recommended to evaluate long-term health and environmental impacts.