title: Gaining a Critical Mass: A Dose Metric Conversion Case Study Using Silver Nanoparticles.
abstract: Mass concentration is the standard convention to express exposure in ecotoxicology for dissolved substances. However, nanotoxicology has challenged the suitability of the mass concentration dose metric. Alternative metrics often discussed in the literature include particle number, surface area, and ion release (kinetics, equilibrium). It is unlikely that any single metric is universally applicable to all types of nanoparticles. However, determining the optimal metric for a specific type of nanoparticle requires novel studies to generate supportive data and employ methods to compensate for current analytical capability gaps. This investigation generated acute toxicity data for two standard species (Ceriodaphnia dubia, Pimephales promelas) exposed to five sizes (10, 20, 30, 60, 100 nm) of monodispersed citrate- and polyvinylpyrrolidone-coated silver nanoparticles. Particles were sized by various techniques to populate available models for expressing the particle number, surface area, and dissolved fraction. Results indicate that the acute toxicity of the tested silver nanoparticles is best expressed by ion release, and is relatable to total exposed surface area. Particle number was not relatable to the observed acute silver nanoparticle effects.
authors.affiliation: U.S. Army Engineer Research and Development Center , Environmental Laboratory, Vicksburg, Mississippi 39180, United States.
authors.forename: Alan J
authors.initials: AJ
authors.lastname: Kennedy
authors.affiliation: Virginia Tech Institute for Critical Technology and Applied Science (ICTAS) , Blacksburg, Virginia 24060, United States.|NanoSafe, Inc. , Blacksburg, Virginia 24060, United States.
authors.forename: Matthew S
authors.initials: MS
authors.lastname: Hull
authors.affiliation: NanoSafe, Inc. , Blacksburg, Virginia 24060, United States.
authors.forename: Stephen
authors.initials: S
authors.lastname: Diamond
authors.affiliation: U.S. Army Engineer Research and Development Center , Environmental Laboratory, Vicksburg, Mississippi 39180, United States.
authors.forename: Mark
authors.initials: M
authors.lastname: Chappell
authors.affiliation: U.S. Army Engineer Research and Development Center , Environmental Laboratory, Vicksburg, Mississippi 39180, United States.
authors.forename: Anthony J
authors.initials: AJ
authors.lastname: Bednar
authors.affiliation: U.S. Army Engineer Research and Development Center , Environmental Laboratory, Vicksburg, Mississippi 39180, United States.
authors.forename: Jennifer G
authors.initials: JG
authors.lastname: Laird
authors.affiliation: U.S. Army Engineer Research and Development Center , Environmental Laboratory, Vicksburg, Mississippi 39180, United States.
authors.forename: Nicholas L
authors.initials: NL
authors.lastname: Melby
authors.affiliation: U.S. Army Engineer Research and Development Center , Environmental Laboratory, Vicksburg, Mississippi 39180, United States.
authors.forename: Jeffery A
authors.initials: JA
authors.lastname: Steevens
mesh_terms: D000818:Animals; D019343:Citric Acid / Q000737:chemistry; D033361:Cladocera / Q000187:drug effects; D003530:Cyprinidae; D008962:Models, Theoretical; D053758:Nanoparticles / Q000737:chemistry / Q000633:toxicity*; D010316:Particle Size; D011205:Povidone / Q000737:chemistry; D012834:Silver / Q000737:chemistry / Q000633:toxicity*; D023382:Toxicity Tests, Acute / Q000379:methods; D014116:Toxicology / Q000379:methods*
chemical_list: D019343:Citric Acid; D012834:Silver; D011205:Povidone