title: Effect of natural organic matter on the photo-induced toxicity of titanium dioxide nanoparticles.
abstract: Nano-titanium dioxide (TiO2) is the most widely used form of nanoparticles in commercial industry and comes in 2 main configurations: rutile and anatase. Rutile TiO2is used in ultraviolet (UV) screening applications, whereas anatase TiO2crystals have a surface defect that makes them photoreactive. There are numerous reports in the literature of photo-induced toxicity to aquatic organisms following coexposure to anatase nano-TiO2and UV. All natural freshwater contains varying amounts of natural organic matter (NOM), which can drive UV attenuation and quench reactive oxygen species (ROS) in aquatic ecosystems. The present research examined how NOM alters the photo-induced toxicity of anatase nano-TiO2. Daphnia magna neonates were coexposed to NOM and photoexcited anatase nano-TiO2for 48 h. Natural organic matter concentrations as low as 4 mg/L reduced anatase nano-TiO2toxicity by nearly 100%. These concentrations of NOM attenuated UV by <10% in the exposure system. However, ROS production measured using a fluorescence assay was significantly reduced in a NOM concentration--dependent manner. Taken together, these data suggest that NOM reduces anatase nano-TiO2toxicity via an ROS quenching mechanism and not by attenuation of UV. Environ Toxicol Chem 2017;36:1661-1666. © 2016 SETAC.
authors.affiliation: Department of Biological Sciences & Advanced Environmental Research Institute, University of North Texas, Denton, Texas, USA.
authors.forename: Alexis M
authors.initials: AM
authors.lastname: Wormington
authors.affiliation: Department of Biological Sciences & Institute of Environmental Toxicology, Clemson University, Pendleton, South Carolina, USA.
authors.forename: Jason
authors.initials: J
authors.lastname: Coral
authors.affiliation: Department of Biological Sciences & Advanced Environmental Research Institute, University of North Texas, Denton, Texas, USA.
authors.forename: Matthew M
authors.initials: MM
authors.lastname: Alloy
authors.affiliation: Department of Biological Sciences & Advanced Environmental Research Institute, University of North Texas, Denton, Texas, USA.
authors.forename: Carmen L
authors.initials: CL
authors.lastname: Delmarè
authors.affiliation: Department of Biological Sciences & Institute of Environmental Toxicology, Clemson University, Pendleton, South Carolina, USA.
authors.forename: Charles M
authors.initials: CM
authors.lastname: Mansfield
authors.affiliation: Department of Biological Sciences & Institute of Environmental Toxicology, Clemson University, Pendleton, South Carolina, USA.
authors.forename: Stephen J
authors.initials: SJ
authors.lastname: Klaine
authors.affiliation: Department of Environmental & Global Health, University of Florida, Gainesville, Florida, USA.
authors.forename: Joseph H
authors.initials: JH
authors.lastname: Bisesi
authors.affiliation: Department of Biological Sciences & Advanced Environmental Research Institute, University of North Texas, Denton, Texas, USA.
authors.forename: Aaron P
authors.initials: AP
authors.lastname: Roberts
mesh_terms: D000818:Animals; D003621:Daphnia / Q000187:drug effects*; D006812:Humic Substances; D008027:Light; D053768:Metal Nanoparticles / Q000633:toxicity*; D053758:Nanoparticles / Q000633:toxicity; D017382:Reactive Oxygen Species; D014025:Titanium / Q000633:toxicity*
chemical_list: D006812:Humic Substances; D017382:Reactive Oxygen Species; C009495:titanium dioxide; D014025:Titanium
keywords: Anatase; Daphnia magna; Natural organic matter; Photo-induced toxicity; Titanium dioxide nanoparticles