Health risk assessment of PAHs and heavy metal levels in periwinkles (Pachymelania fusca mutans) and crabs (Scylla serrata) consumed in crude oil-contaminated coastal regions of Southern Nigeria

Abstract

This study was conducted to evaluate the health risks related to eating crabs and periwinkles from Southern Nigerian coastal areas that are contaminated by crude oil. Periwinkles and crabs from contaminated locations were tested for Polycyclic aromatic hydrocarbon (PAH) and heavy metal (HM) levels using US-EPA standard, and the health risks to humans of eating these seafood were assessed. 20 samples of periwinkles and crabs were collected from crude oil-polluted coastal areas. Health risk assessments were conducted using Dietary Daily Intake (DDI), PAH4 index, Carcinogenic Toxic Equivalent (TEQs), Excess Cancer Risk (ECR) for PAHs, as well as Hazard Quotient (HQ) and Cancer Risk Assessment (CRA) for HMs. The PAH concentration in periwinkles and crabs are 0.76 mg/kg and 0.49 mg/kg respectively. Dietary daily intake (DDI) of individual PAHs for Periwinkle ranged from 0 to 0.0126 and for crabs, it ranged from 0 to x10⁻⁴. The ECR evaluated for Periwinkle and crabs ranges from 0 to 9 × 10⁻⁷, and 0–2.1 × 10⁻⁷ respectively. The TEQ for periwinkle is 0.12874 mg/kg and 0.15646 mg/kg for crabs. The evaluated PAH4 is 0.1061 mg/kg for Periwinkle and 0.1352 mg/kg for Crabs. The concentration of PAHs was found to be 0.76 mg/kg in periwinkles and 0.49 mg/kg in crabs. DDI values for individual PAHs ranged from 0 to 0.0126 for periwinkles and 0–0 to x10⁻⁴ for crabs. ECR values ranged from 0 to 9 x 10⁻⁷ for periwinkles and 0–2.1 x 10⁻⁷ for crabs. TEQ values were 0.12874 mg/kg for periwinkles and 0.15646 mg/kg for crabs. Deduction from PAH4 index exceeded the permissible limit set by the European Union. TEQ values indicate that periwinkles were below the screening value (SV) of 0.0389 mg/kg, while crabs exceeded it. The ECR for the shellfish was also found to be within the acceptable risk level. All HMs were within EPA permissible limits except cadmium (Cd). HQ indicated potential health risks from crab consumption, while CRA showed no carcinogenic risk from either shellfish. The study recommends that if crude oil pollution in coastal areas continues, severe health implications will be inevitable. Therefore, it is crucial to implement measures to mitigate pollution levels and monitor seafood safety regularly to protect public health.