Assessment of Heavy Metals and Polyaromatic Hydrocarbon (PAHs) Contamination in Periwinkle (Tympanotonus fuscatus) from Effurun Market, Delta State, Nigeria

Abstract

Aquatic contamination associated with petroleum exploration, industrial discharge, and urban activities remains a major environmental and public health concern in the Niger Delta region of Nigeria. This study assessed the concentrations of heavy metals and polycyclic aromatic hydrocarbons (PAHs) in Tympanotonus fuscatus obtained from Effurun Market, Delta State, Nigeria, and evaluated the associated human health risks through dietary exposure assessment. Samples were analysed for selected heavy metals using Inductively Coupled Plasma–Optical Emission Spectrometry (ICP–OES) and for PAHs using Gas Chromatography–Mass Spectrometry (GC–MS). Exposure and risk assessments were conducted using Estimated Daily Intake (EDI), Hazard Quotient (HQ), Hazard Index (HI), and Carcinogenic Risk (CR) models for children, adults, and pregnant women. Copper recorded the highest concentration (45.104 ± 5.089 mg/kg) and exceeded the FAO/WHO permissible limit by approximately 50%, while zinc and manganese occurred at comparatively lower concentrations. Most analysed heavy metals, including cadmium and lead, were below analytical detection limits. Phenanthrene and pyrene were the only detected PAHs, whereas carcinogenic high molecular weight PAHs were not detected. EDI, HQ, HI, and CR values for all population groups remained below established regulatory thresholds, indicating negligible non-carcinogenic and carcinogenic health risks under current exposure conditions. Nevertheless, the elevated copper concentration reflects ongoing anthropogenic contamination within the Niger Delta aquatic environment and highlights the need for continuous environmental monitoring and strengthened pollution control measures to safeguard seafood quality and public health.