title: Toxicity and transcriptomic analysis in Hyalella azteca suggests increased exposure and susceptibility of epibenthic organisms to zinc oxide nanoparticles.
abstract: Nanoparticles (NPs) are expected to make their way into the aquatic environment where sedimentation of particles will likely occur, putting benthic organisms at particular risk. Therefore, organisms such as Hyalella azteca, an epibenthic crustacean which forages at the sediment surface, is likely to have a high potential exposure. Here we show that zinc oxide (ZnO) NPs are more toxic to H. azteca compared with the corresponding metal ion, Zn(2+). Dissolution of ZnO NPs contributes about 50% of the Zn measured in the ZnO NP suspensions, and cannot account for the toxicity of these particles to H. azteca. However, gene expression analysis is unable to distinguish between the ZnO NP exposures and zinc sulfate (ZnSO4) exposures at equitoxic concentrations. These results lead us to hypothesize that ZnO NPs provide an enhanced exposure route for Zn(2+) uptake into H. azteca, and possibly other sediment dwelling organisms. Our study supports the prediction that sediment dwelling organisms are highly susceptible to the effects of ZnO NPs and should be considered in the risk assessment of these nanomaterials.
authors.affiliation: School for the Environment, University of Massachusetts, Boston, Boston, Massachusetts 02125, USA. Helen.poynton@umb.edu
authors.forename: Helen C
authors.initials: HC
authors.lastname: Poynton
authors.forename: James M
authors.initials: JM
authors.lastname: Lazorchak
authors.forename: Christopher A
authors.initials: CA
authors.lastname: Impellitteri
authors.forename: Bonnie
authors.initials: B
authors.lastname: Blalock
authors.forename: Mark E
authors.initials: ME
authors.lastname: Smith
authors.forename: Katherine
authors.initials: K
authors.lastname: Struewing
authors.forename: Jason
authors.initials: J
authors.lastname: Unrine
authors.forename: Deborah
authors.initials: D
authors.lastname: Roose
mesh_terms: D033304:Amphipoda / Q000187:drug effects* / Q000378:metabolism; D000818:Animals; D020869:Gene Expression Profiling; D053758:Nanoparticles / Q000633:toxicity*; D018570:Risk Assessment; D023382:Toxicity Tests, Acute; D015034:Zinc Oxide / Q000633:toxicity*; D019287:Zinc Sulfate / Q000633:toxicity
chemical_list: D019287:Zinc Sulfate; D015034:Zinc Oxide