Internal concentrations of cadmium, nickel and zinc in the land snail Cornu aspersum and human health risk assessment for consumers: a case study in tunisian regions

Abstract

Heavy metal pollution in terrestrial environments is a critical concern due to persistence and bioaccumulation, posing long-term risks to human health. Land snails, such as Cornu aspersum (Helix aspersa), are key consumers in terrestrial ecosystems and serve as bioindicators of chemical contamination. In this study, concentrations of zinc (Zn), cadmium (Cd), and nickel (Ni) were measured in the soft tissues and shells of Cornu aspersum collected from seven Tunisian regions using flame atomic absorption spectrophotometry. All metals were detected in every sample, with levels varying by site and body part. Zn and Cd concentrations in snail flesh were below international safety limits, whereas Ni exceeded recommended thresholds in most regions except Mateur, Sfax, and Houidh. Compared with global reports, concentrations were comparable or slightly lower. Human health risks were assessed using Target Hazard Quotient (THQ), Hazard Index (HI), and Cancer Risk (CR). THQ values were < 1 across all sites, except Cd at Ras Enjela. HI values exceeded 1 only at Ras Enjela, indicating potential non-carcinogenic risk. CR values surpassed the threshold of 1.0 × 10⁻⁴ in Zaghouan, Teskreya, and Ras Enjela, reflecting possible cancer risk from Ni. This first Tunisian assessment provides essential baseline data for environmental monitoring and public health.

Keywords: Cornu aspersum; Bioconcentration; Health risk; Heavy metals; Trace element; Tunisia.