Ecotoxicological effects of silver nanoparticles in marine mussels

In the marine bioindicator species M. galloprovincialis Lam we predicted toxicity and bioaccumulation of 5 nm alkane-coated and 50 nm uncoated silver nanoparticles (AgNPs) along with Ag+, as a function of the actual dose level. We generated a time persistence model of silver concentration in seawater and used the Area Under the Curve (AUC) as independent variable in hazard assessment. This approach allowed us to evaluate unbiased ecotoxicological endpoints for acute (survival) and chronic toxicity (byssal adhesion). Logistic regression analysis rendered LC5096h values of 0.68 {+/-} 0.08; 1.00 {+/-} 0.20; 1.00 {+/-} 0.42 mg h L-1 respectively for Ag+, 5 nm and 50 nm AgNP posing no evidence the silver form is a necessary variable to predict the survival outcome. By contrast, for byssal adhesion regression analysis revealed a much higher toxicological potential of Ag+ vs AgNPs, 0.0021 {+/-} 0.0009; 0.053 {+/-} 0.016; 0.021 (no computable error for 50 nm AgNP) mg h L-1, and undoubtedly confirmed a role of the silver form. Bioaccumulation was higher for Ag+ > 5 nm AgNP > 50 nm AgNP reflecting a parallel with the preferential uptake route / target organ. We, eventually, provided a full range of toxicological endpoints to derive risk quotients.