Mixtures of potentially toxic elements in bivalve mollusks: contamination patterns and probabilistic assessment of cumulative health risk

Potentially toxic elements (Ag, total As, B, Ba, Be, Cd, total Cr, total Hg, Mn, Mo, Ni, Pb, Sb, Se, Sr, U, V, and Zn) were quantified in mussels (Mytilus galloprovincialis, n = 102 batches) and clams (Chamelea gallina, n = 26 batches) using inductively coupled plasma mass spectrometry and direct mercury analysis. A probabilistic dietary exposure assessment was conducted for Italian children, adolescents, and adults to evaluate cumulative health risks using experimentally determined or concentrations estimated through conversion factors (for MeHg, iAs, Cr(III), and Cr(VI)). All samples exhibited low contamination levels, with Pb, Cd, and iAs concentrations below European regulatory limits. Non-cancer risk associated with simultaneous exposure to Ag, B, Ba, Be, Cd, Cr(III), Cr(VI), iAs, MeHg, Mn, Mo, Ni, Sb, Se, Sr, U, V, and Zn was negligible (Hazard Index <1) and primarily driven by iAs, Cd, Se, and Zn. In contrast, cumulative exposure to iAs and Cr(VI) was above the acceptable cancer risk threshold (Total Cancer Risk >1 × 10−4) with a 100% probability across all demographic groups and for both bivalve species. Despite not being directly measured, Cr(VI) contributed over 99%, even though assumed to represent only 1% of total Cr. Sensitivity analysis indicated that exposure frequency, followed by consumption rate, was the main determinants of overall risk. These findings suggest that chronic exposure to elemental mixtures may represent a potential health concern, underscoring the need to fully integrate mixture-based approaches into routine food risk assessment and to prioritize dietary habits, alongside contamination reduction strategies, to safeguard public health.