title: Natural water as the test medium for Ag and CuO nanoparticle hazard evaluation: An interlaboratory case study.
abstract: Engineered nanoparticles (NPs) have realistic potential of reaching natural waterbodies and of exerting toxicity to freshwater organisms. The toxicity may be influenced by the composition of natural waters as crucial NP properties are influenced by water constituents. To tackle this issue, a case study was set up in the framework of EU FP7 NanoValid project, performing an interlaboratory hazard evaluation of NPs in natural freshwater. Ag and CuO NPs were selected as model NPs because of their potentially high toxicity in the freshwater. Daphnia magna (OECD202) and Danio rerio embryo (OECD236) assays were used to evaluate NP toxicity in natural water, sampled from Lake Greifen and Lake Lucerne (Switzerland). Dissolution of the NPs was evaluated by ultrafiltration, ultracentrifugation and metal specific sensor bacteria. Ag NP size was stable in natural water while CuO NPs agglomerated and settled rapidly. Ag NP suspensions contained a large fraction of Ag(+) ions and CuO NP suspensions had low concentration of Cu(2+) ions. Ag NPs were very toxic (48 h EC50 1-5.5 μg Ag/L) to D. magna as well as to D. rerio embryos (96 h EC50 8.8-61 μg Ag/L) in both standard media and natural waters with results in good agreement between laboratories. CuO NP toxicity to D. magna differed significantly between the laboratories with 48 h EC50 0.9-11 mg Cu/L in standard media, 5.7-75 mg Cu/L in Lake Greifen and 5.5-26 mg Cu/L in Lake Lucerne. No toxicity of CuO NP to zebrafish embryos was detected up to 100 mg/L independent of the medium used. The results show that Ag and CuO NP toxicity may be higher in natural water than in the standard media due to differences in composition. NP environmental hazard evaluation can and should be carried out in natural water to obtain more realistic estimates on the toxicity.
authors.affiliation: Laboratory of Environmental Toxicology, National Institute of Chemical Physics and Biophysics, Akadeemia tee 23, 12618 Tallinn, Estonia. Electronic address: margit.heinlaan@kbfi.ee.
authors.forename: Margit
authors.initials: M
authors.lastname: Heinlaan
authors.affiliation: Laboratory of Environmental Toxicology, National Institute of Chemical Physics and Biophysics, Akadeemia tee 23, 12618 Tallinn, Estonia; Department of Materials Science, Tallinn University of Technology, Ehitajate tee 5, 19086 Tallinn, Estonia.
authors.forename: Marge
authors.initials: M
authors.lastname: Muna
authors.affiliation: Eawag, Swiss Federal Institute of Aquatic Science and Technology, Überlandstrasse 133, 8600 Dübendorf, Switzerland.
authors.forename: Melanie
authors.initials: M
authors.lastname: Knöbel
authors.affiliation: Eawag, Swiss Federal Institute of Aquatic Science and Technology, Überlandstrasse 133, 8600 Dübendorf, Switzerland.
authors.forename: David
authors.initials: D
authors.lastname: Kistler
authors.affiliation: Eawag, Swiss Federal Institute of Aquatic Science and Technology, Überlandstrasse 133, 8600 Dübendorf, Switzerland.
authors.forename: Niksa
authors.initials: N
authors.lastname: Odzak
authors.affiliation: Helmholtz Centre for Environmental Research - UFZ, Department of Bioanalytical Ecotoxicology, Permoserstr.15, 04318 Leipzig, Germany.
authors.forename: Dana
authors.initials: D
authors.lastname: Kühnel
authors.affiliation: Helmholtz Centre for Environmental Research - UFZ, Department of Bioanalytical Ecotoxicology, Permoserstr.15, 04318 Leipzig, Germany.
authors.forename: Josefine
authors.initials: J
authors.lastname: Müller
authors.affiliation: Institute of Life Sciences, School of Science and Technology, Ahmedabad University, University Road, Navrangpura, Ahmedabad, 380009, Gujarat, India.
authors.forename: Govind Sharan
authors.initials: GS
authors.lastname: Gupta
authors.affiliation: Institute of Life Sciences, School of Science and Technology, Ahmedabad University, University Road, Navrangpura, Ahmedabad, 380009, Gujarat, India.
authors.forename: Ashutosh
authors.initials: A
authors.lastname: Kumar
authors.affiliation: Institute of Life Sciences, School of Science and Technology, Ahmedabad University, University Road, Navrangpura, Ahmedabad, 380009, Gujarat, India.
authors.forename: Rishi
authors.initials: R
authors.lastname: Shanker
authors.affiliation: Eawag, Swiss Federal Institute of Aquatic Science and Technology, Überlandstrasse 133, 8600 Dübendorf, Switzerland. Electronic address: laura.sigg@eawag.ch.
authors.forename: Laura
authors.initials: L
authors.lastname: Sigg
mesh_terms: D000818:Animals; D003300:Copper / Q000032:analysis / Q000737:chemistry / Q000633:toxicity*; D003621:Daphnia / Q000187:drug effects*; D015386:Hazardous Substances / Q000032:analysis* / Q000737:chemistry / Q000633:toxicity; D060106:Lakes; D053768:Metal Nanoparticles / Q000032:analysis / Q000737:chemistry / Q000633:toxicity*; D012834:Silver / Q000032:analysis / Q000737:chemistry / Q000633:toxicity*; D013557:Switzerland; D018675:Toxicity Tests; D014874:Water Pollutants, Chemical / Q000032:analysis / Q000737:chemistry / Q000633:toxicity*; D015027:Zebrafish
chemical_list: D015386:Hazardous Substances; D014874:Water Pollutants, Chemical; D012834:Silver; D003300:Copper; C030973:cupric oxide
keywords: Danio rerio; Daphnia magna; Environmentally relevant conditions; Freshwater; NanoValid; Zebrafish