Multi-scale assessment of metal and metalloid contamination and bioaccumulation in clams (Ruditapes spp.) along the French coasts: implications for environmental and human health risks.

Metal and metalloid contamination from terrestrial and maritime human activities increasingly threatens coastal ecosystems, inducing ecotoxicological effects and potential risks to human health. Filter-feeding intertidal species such as Ruditapes spp. can bioaccumulate these contaminants and are therefore widely used for coastal environmental monitoring. For ecotoxicological purposes, seasonal and spatial concentrations of metals (Al, Cd, Cr, Co, Cu, Fe, Mn, Ni, Pb, V and Zn) and the metalloid As were analysed in sediments and clam tissues from the French English Channel and Atlantic coasts, using a multi-scale approach (local, regional and national). Spatial differences were mainly observed at local and regional scales, whereas no marked differences were detected at the national scale. Bioaccumulation in Ruditapes spp. was compared with Mytilus edulis and Crassostrea gigas, two other commonly used sentinel species. The species- and site-specific accumulation patterns suggested that employing multiple species could enhance environmental monitoring strategies. As showed the highest bioaccumulation values, followed by Zn, Cu, Ni and Co. Finally, environmental and human health risk assessments indicated that, among the studied elements, only As may raise concern in some sites, while risks associated with other metals remained low.