Assessing the potential risks to zebrafish posed by environmentally relevant copper and silver nanoparticles

The manufacture of large quantities of engineered nanomaterials (NMs) may lead to unintended contamination of aquatic ecosystems. Biologically based monitoring techniques need to be developed to detect these emerging NMs. The purpose of this study was to develop a risk-based probability model to predict the potential hazards of nanoecotoxicity toward aquatic organisms posed by waterborne copper and silver nanoparticles (Cu/Ag NPs). Published experimental evidence based on Cu/Ag NP-zebrafish (Danio rerio) systems was adopted as the study data. A Hill model was used to reconstruct a concentration-mortality response profile. A cumulative Weibull predictive model was employed to estimate exposure thresholds. The derived probabilistic model can predict the potential risk of environmentally relevant Cu/Ag NPs for major Taiwanese rivers with predicted environmental concentrations of 0.06 (95% confidence interval (CI): 0.01-0.92) mg L-1 for Cu NPs and 0.04 (0.01-0.11) mg L-1 for Ag NPs. The results indicated that estimated thresholds were 0.10-0.48 mg L-1 (95% CI) for Cu NPs and 2.69-2.73 mg L-1 for Ag NPs. The probabilities of a risk quotient (RQ) of >1 ranged 17%-81% for zebrafish exposed to Cu NPs. This study found that Ag NP exposure scenarios posed no significant risks to zebrafish (RQ << 0.1). (C) 2012 Elsevier B.V. All rights reserved.