Processing-induced Variations in Heavy Metal Content of Periwinkle (Tympanotonus fuscatus): Blowout Versus Shelling Method and Health Risk Assessment

Heavy metals are persistent environmental pollutants that pose risks to aquatic life and humans due to their non-biodegradable nature, bio-accumulation and toxicity. This study assessed the concentrations of Cadmium (Cd), Arsenic (As), Zinc (Zn), Lead (Pb), Copper (Cu), and Mercury (Hg) in Tympanotonus fuscatus (periwinkle) to evaluate potential processing-induced heavy metal content and health risk assessment. Samples were collected from three stations at Eagle Island, Port Harcourt, Nigeria. Metal concentrations were determined using an Atomic Absorption Spectrophotometer (AAS), and data were analyzed with SPSS version 25, with a significant difference set at a P ≤ 0.05. The data obtained were used to compute the health risk assessment. Results showed significantly higher levels of heavy metal in the blowout than in the shelling method: Cd: 0.053±0.001 (blowout), 0.0033±0.0001 (shelling); As: 0.175±0.004 (blowout), 0.038±0.001 (shelling); Zn: 6.91±0.27 (blowout), 3.42±0.19 (shelling); Pb 4.92 ± 0.70 mg/kg (blowout), 1.77 ± 0.26 mg/kg (shelling), Cu 12.96 ± 1.75 mg/kg (blowout) 4.86 ± 0.74 mg/kg (shelling), and Hg 0.043 ± 0.006 mg/kg (blowout) 0.006 ± 0.001 mg/kg (shelling). The target health Quotient for periwinkles processed by blowout was found to be >1, shelling was <1. In the same vein, the ECR of the blowout method was also greater than the acceptable range of  10-6-10-4 . ECR values of >1.0x10-4 indicate a lifetime carcinogen risk. Consequently, the higher heavy metal concentrations in blowout compared to shelling suggest a health risk, which includes both cancer risk and non-cancer risk if consumed without deshelling. Following these results, we recommend the shelling method of processing to minimise heavy metal exposure.