title: Aquatic ecotoxicity tests of some nanomaterials.
abstract: Nanoparticles of TiO2, ZrO2, AL2O3, CeO2, fullerene (C60), single-walled carbon nanotubes, and polymethylmethacrylate were tested for ecotoxic effects using one or more ecotoxicity endpoints: Microtox (bacteria), pulse-amplitude modulation (algae), Chydotox (crustaceans), and Biolog (soil enzymes). No appreciable effects were observed at nominal concentrations of up to 100 mg/L. Dilution of nanoparticle suspensions, either in ultrapure (Milli-Q) water or in natural (pond) water, led to formation of larger particles, which settled easily. (Nano)particles in water were characterized by means of atomic force microscopy, energy-dispersive x-ray analysis, inductively coupled plasma-mass spectrometry, flow cytometry, and spectrophotometry. It is concluded that the absence of ecotoxicity is the result of low concentrations of free nanoparticles in the tests, and it is suggested that colloid (in)stability is of primary importance in explaining ecotoxic effects of nanoparticles in the natural environment.
authors.affiliation: Laboratory for Ecological Risk Assessment, National Institute of Public Health and the Environment (RIVM), P.O. Box 1, 3720 BA Bilthoven, The Netherlands.
authors.forename: Ilona
authors.initials: I
authors.lastname: Velzeboer
authors.forename: A Jan
authors.initials: AJ
authors.lastname: Hendriks
authors.forename: Ad M J
authors.initials: AM
authors.lastname: Ragas
authors.forename: Dik
authors.initials: D
authors.lastname: Van de Meent
mesh_terms: D048908:Aliivibrio fischeri / Q000187:drug effects; D000818:Animals; D001419:Bacteria / Q000187:drug effects; D000460:Chlorophyta / Q000187:drug effects; D033361:Cladocera; D005434:Flow Cytometry; D049449:Luminescence; D013058:Mass Spectrometry; D018625:Microscopy, Atomic Force; D053758:Nanoparticles / Q000633:toxicity*; D010316:Particle Size; D012988:Soil Microbiology; D013056:Spectrophotometry, Ultraviolet; D018675:Toxicity Tests; D014461:Ultracentrifugation; D014874:Water Pollutants, Chemical / Q000633:toxicity*
chemical_list: D014874:Water Pollutants, Chemical