Bioaccumulation and effects of titanium dioxide nanoparticles and bulk in the clam Ruditapes philippinarum

Biochemical and cellular responses to low concentrations of TiO2 nanoparticles (nTiO2, 1 and 10 μg/L) and bulk (bTiO2, 10 μg/L) were evaluated in gills, digestive gland and haemolymph of the clam Ruditapes philippinarum after1, 3 and 7 days' exposure. At 7 days, titanium content was determined in gills and digestive gland. nTiO2 significantly increased antioxidant enzyme activities in both tissues, and lipid peroxidation in digestive gland at 10 μg/L only, and affected glutathione S-transferase activity. Slighter variations were observed in bTiO2-treated clams. A significant Ti bioaccumulation was detected in both gills and digestive gland of 10 μg nTiO2/L-exposed clams. In haemolymph, nTiO2 affected total haemocyte count, haemocyte proliferation, haemocyte diameter and volume, and induced DNA damage. Overall, this study demonstrated that TiO2 alters most of the biomarkers measured in clams, although responses were differently modulated depending on tissues and exposure conditions, and indicated that nTiO2 can be accumulated by bivalves, suggesting a potential risk for filter-feeding animals.