title: Chronic TiO₂ nanoparticle exposure to a benthic organism, Hyalella azteca: impact of solar UV radiation and material surface coatings on toxicity.
abstract: There is limited information on the chronic effects of nanomaterials to benthic organisms, as well as environmental mitigating factors that might influence this toxicity. The present study aimed to fill these data gaps by examining various growth endpoints (weight gain, instantaneous growth rate, and total protein content) for up to a 21 d sediment exposure of TiO2 nanoparticles (nano-TiO2) to a representative benthic species, Hyalella azteca. An uncoated standard, P25, and an Al(OH)3 coated nano-TiO2 used in commercial products were added to sediment at 20 mg/L or 100 mg/L Under test conditions, UV exposure alone was shown to be a greater cause of toxicity than even these high levels of nano-TiO2 exposure, indicating that different hazards need to be addressed in toxicity testing scenarios. In addition, this study showed the effectiveness of a surface coating on the decreased photoactivity of the material, as the addition of an Al(OH)3 coating showed a dramatic decrease in reactive oxygen species (ROS) production. However, this reduced photoactivity was found to be partially restored when the coating had been degraded, leading to the need for future toxicity tests which examine the implications of weathering events on particle surface coatings.
authors.affiliation: Office of Research and Development, Mid-Continent Ecology Division, National Health and Environmental Effects Research Laboratory, U.S. Environmental Protection Agency, Duluth, MN, 55804, USA.
authors.forename: Lindsay K
authors.initials: LK
authors.lastname: Wallis
authors.affiliation: Nanosafe Inc., Blacksburg, VA, 24060, USA.
authors.forename: Stephen A
authors.initials: SA
authors.lastname: Diamond
authors.affiliation: University of Wisconsin-Milwaukee, Zilber School of Public Health, Milwaukee, WI, 53211, USA.
authors.forename: Hongbo
authors.initials: H
authors.lastname: Ma
authors.affiliation: Office of Research and Development, Mid-Continent Ecology Division, National Health and Environmental Effects Research Laboratory, U.S. Environmental Protection Agency, Duluth, MN, 55804, USA.
authors.forename: Dale J
authors.initials: DJ
authors.lastname: Hoff
authors.affiliation: National Risk Management Research Laboratory, U.S. Environmental Protection Agency, Cincinnati, OH 45268, USA.
authors.forename: Souhail R
authors.initials: SR
authors.lastname: Al-Abed
authors.affiliation: Office of Research and Development, Mid-Continent Ecology Division, National Health and Environmental Effects Research Laboratory, U.S. Environmental Protection Agency, Duluth, MN, 55804, USA. Electronic address: lishibinepa@gmail.com.
authors.forename: Shibin
authors.initials: S
authors.lastname: Li
mesh_terms: D033304:Amphipoda; D000818:Animals; D053758:Nanoparticles / Q000737:chemistry / Q000633:toxicity*; D055668:Photochemical Processes; D013499:Surface Properties; D014025:Titanium / Q000737:chemistry / Q000633:toxicity*; D036401:Toxicity Tests, Chronic; D014466:Ultraviolet Rays; D014874:Water Pollutants, Chemical / Q000737:chemistry / Q000633:toxicity*
chemical_list: D014874:Water Pollutants, Chemical; C009495:titanium dioxide; D014025:Titanium
keywords: Chronic toxicity; Growth; Hyalella azteca; Nano-TiO(2); Phototoxicity