Trace element contamination in sediments and edible gastropods from northwestern Morocco: Outdated consumption data...

Trace element (TE) contamination threatens coastal ecosystems and seafood safety. However, gastropods remain underutilized as bioindicators along the Moroccan Atlantic coast, despite their widespread consumption by coastal populations. This study assessed concentrations of TEs (Cd, Cr, Cu, Fe, and Zn) in surficial sediments and tissues of two edible gastropods, Patella ulyssiponensis and Phorcus lineatus, across four seasons at an industrially impacted site (MS) and a less impacted site (CB) along the Safi coastline (NW Morocco). Multi-index sediment assessment revealed severe Cd contamination at site MS (I_geo Class 4; CF > 17), with Enrichment Factor analysis confirming anthropogenic Cd at both sites (EF = 8.93-31.22), whereas Cr remained lithogenic (EF < 2). Cd was the primary ecological risk driver (∑RQ = 8.17 at site MS vs. 4.85 at CB). P. ulyssiponensis accumulated 1.7-fold higher Cd and Cu than P. lineatus, with both species demonstrating Cd micro-concentration (BSAF > 1). Critically, using current FAO-derived national consumption rates (51.2 g/day) versus outdated rates (2.74 g/day), combined with dry-to-wet weight correction, increased the risk estimates 19-fold. Mean Hazard Index reached 19.3 for children, 4.00 for men, and 4.17 for women, and Total Cancer Risk exceeded the unacceptable threshold (10^-4). These findings demonstrate that previous regional shellfish assessments relying on outdated consumption data and dry weight expression have systematically underestimated health risks, a methodological concern applicable to any data-limited country where these practices are prevalent.