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Comparison of nanosilver and ionic silver toxicity in Daphnia magna and Pimephales promelas
Citation:
Hoheisel, S., S. Diamond, AND D. Mount. Comparison of nanosilver and ionic silver toxicity in Daphnia magna and Pimephales promelas. ENVIRONMENTAL TOXICOLOGY AND CHEMISTRY. Society of Environmental Toxicology and Chemistry, Pensacola, FL, 31(11):2557-2563, (2012).
Impact/Purpose:
This work evaluates the relative contribution of soluble (Ag+) silver and and nano-scale silver particles (n-Ag) and thus addresses an important issue relative to potential ecological risk of n-Ag and of other partially-soluble metal nanoparticles. We used acute to chronic (based on a sub-lethality assay) ratios and the relative sensitivities of two species known to differ considerably in their response to silver salts, and an ion exchange approach for isolating particles from soluble silver species, to determine if the level of toxicity or the mode of action of n-Ag is unique relative to soluble silver species. Our results did not reveal unique responses for nano-silver, and strongly suggests that the majority of it's toxicity is attributable to free species released from silver particles. We believe this manuscript can make a significant contribution to the literature. It is the first study that carefully compares responses of two species having well-quantified responses to silver salts, compares acute and sub-lethal responses for those species, and includes extensive and careful characterization of materials before and during testing. Our findings also corroborate acute levels of toxicity and the relative contribution of soluble and particulate forms of silver associated with nano-siver formulations. A final note; the poster presentation of this work won the Best Student Poster Award for Sarah Hoheisel at the national NA SETAC meeting two years ago.
Description:
This work evaluates the relative contribution of soluble (Ag+) silver and and nano-scale silver particles (n-Ag) and thus addresses an important issue relative to potential ecological risk of n-Ag and of other partially-soluble metal nanoparticles. We used acute to chronic (based on a sub-lethality assay) ratios and the relative sensitivities of two species known to differ considerably in their response to silver salts, and an ion exchange approach for isolating particles from soluble silver species, to determine if the level of toxicity or the mode of action of n-Ag is unique relative to soluble silver species. Our results did not reveal unique responses for nano-silver, and strongly suggests that the majority of it's toxicity is attributable to free species released from silver particles. We believe this manuscript can make a significant contribution to the literature. It is the first study that carefully compares responses of two species having well-quantified responses to silver salts, compares acute and sub-lethal responses for those species, and includes extensive and careful characterization of materials before and during testing. Our findings also corroborate acute levels of toxicity and the relative contribution of soluble and particulate forms of silver associated with nano-siver formulations. A final note; the poster presentation of this work won the Best Student Poster Award for Sarah Hoheisel at the national NA SETAC meeting two years ago.
