title: Effects of silver and cerium dioxide micro- and nano-sized particles on Daphnia magna.
abstract: Acute (96 h) and chronic (21 d) exposures of Daphnia magna neonates were carried out with nano- and micro-sized Ag and CeO(2) particles to assess the influence of both material and size of particles on mortality and moulting. Mortality rates for silver in the acute exposures were: AgNP, 56.7 ± 23.3% at 0.1 mg L(-1) and 100 ± 20% at 1 mg L(-1), and micro-Ag, 13.3 ± 6.7% at 0.1 mg L(-1) and 80 ± 20% at 1 mg L(-1). CeO(2) was not acutely toxic at concentrations up to 10 mg L(-1). Mortality for Ag over 21d at concentrations of up to 0.05 mg L(-1) was low, while mortality of 30% was observed for 0.001 mg L(-1) of nano-Ag. CeO(2), with the exception of the 10 mg L(-1) of nano-CeO(2) (100% mortality by day 7), was non-toxic. Inhibition of moulting and growth in the acute study occurred at toxic concentrations (Ag particles), and at 10 mg L(-1) of nano-CeO(2). The chronic study revealed reduced moulting at 0.001 mg L(-1) of nano-Ag and 0.01 and 0.05 mg L(-1) of both sizes of Ag, but there was no impact on D. magna size, and no effects of CeO(2). The toxicity of nano-CeO(2) may be attributed to reduced feeding and physical interference with the daphnids' carapace, resulting in reduced swimming ability. Our results suggest that Ag NPs in particular have the potential to be harmful to aquatic invertebrates after release into the environment, whereas CeO(2) particles appear to cause little adverse effects, and only at environmentally irrelevant concentrations.
authors.affiliation: Edinburgh Napier University, School of Health, Life and Social Sciences, Sighthill Campus, Sighthill Court, Edinburgh EH11 4BN, UK. b.gaiser@hw.ac.uk
authors.forename: Birgit K
authors.initials: BK
authors.lastname: Gaiser
authors.forename: Anamika
authors.initials: A
authors.lastname: Biswas
authors.forename: Philipp
authors.initials: P
authors.lastname: Rosenkranz
authors.forename: Mark A
authors.initials: MA
authors.lastname: Jepson
authors.forename: Jamie R
authors.initials: JR
authors.lastname: Lead
authors.forename: Vicki
authors.initials: V
authors.lastname: Stone
authors.forename: Charles R
authors.initials: CR
authors.lastname: Tyler
authors.forename: Teresa F
authors.initials: TF
authors.lastname: Fernandes
mesh_terms: D000818:Animals; D002563:Cerium / Q000633:toxicity*; D003621:Daphnia / Q000187:drug effects*; D004305:Dose-Response Relationship, Drug; D005247:Feeding Behavior / Q000187:drug effects; D009043:Motor Activity / Q000187:drug effects; D053758:Nanoparticles / Q000633:toxicity*; D010316:Particle Size; D012834:Silver / Q000633:toxicity*; D013550:Swimming; D014874:Water Pollutants, Chemical / Q000633:toxicity*
chemical_list: D014874:Water Pollutants, Chemical; D002563:Cerium; D012834:Silver; C030583:ceric oxide