Spatial Distribution of Potentially Toxic Elements and Polycyclic Aromatic Hydrocarbons in Edible Crabs and Prawns from Selected Niger Delta Aquatic Ecosystems: Human Health Risk Assessment

Abstract

This study investigated potentially toxic elements (PTEs), polycyclic aromatic hydrocarbons (PAHs) and associated health risks in edible crabs and prawns collected from Qua Iboe Estuary, Iko River, Stubbs Creek, Cross River Estuary and Uta Ewa Creek, Niger Delta, Nigeria. Ten PTEs were determined using atomic absorption spectrophotometry, while PAHs were analysed using gas chromatography–mass spectrometry. Estimated daily intake (EDI), hazard index (HI), benzo[a]pyrene-equivalent concentration (BaP-eq) and incremental lifetime cancer risk (ILCR) were evaluated. Iron was the most abundant element, followed by zinc. Uta Ewa Creek recorded the highest concentrations of the measured PTEs, whereas Qua Iboe Estuary generally recorded the lowest. Mean concentrations of all ten elements were higher in crabs than in prawns. Total concentrations of 16 PAHs in crabs ranged from 238 to 476 µg/kg, while the seven measured PAHs in prawns ranged from 92 to 189 µg/kg. Pyrene and fluoranthene were prominent in both organisms. BaP-eq values ranged from 42.509 to 91.205 µg/kg in crabs and 27.464 to 55.031 µg/kg in prawns. Adult HI values were below 1, whereas child HI values exceeded 1 for crabs at all locations and for prawns at Cross River Estuary and Uta Ewa Creek. The highest ILCR estimates occurred in crabs from Uta Ewa Creek. The findings demonstrate spatial and species-related differences in contaminant burdens and highlight the importance of monitoring seafood quality in the Niger Delta.