title: Photo-induced toxicity of titanium dioxide nanoparticles to Daphnia magna under natural sunlight.
abstract: Titanium dioxide nanoparticles (TiO2 NP) are one of the most abundantly utilized nanoparticles in the world. Studies have demonstrated the ability of the anatase crystal of TiO2 NP to produce reactive oxygen species (ROS) in the presence of ultraviolet radiation (UVR), a co-exposure likely to occur in aquatic ecosystems. The goal of this study was to examine the photo-induced toxicity of anatase TiO2 NP under natural sunlight to Daphnia magna. D. magna were exposed to a range of UVR intensities and anatase TiO2 concentrations in an outdoor exposure system using the sun as the source of UVR. Different UVR intensities were achieved using UVR opaque and transparent plastics. AnataseTiO2-NP demonstrated the reciprocal relationship seen in other phototoxic compounds such as polycyclic aromatic hydrocarbons (PAHs) at higher UVR treatments. The calculated 8h LC50 of anatase TiO2 NP was 139 ppb under full intensity ambient natural sunlight, 778 ppb under 50% natural sunlight, and >500 ppm under 10% natural sunlight. Mortality was also compared between animals allowed to accumulate a body burden of anatase TiO2 for 1h and organisms whose first exposure to anatase TiO2 aqueous suspensions occurred under UVR. A significantly greater toxic effect was observed in aqueous, low body burden suspensions than that of TiO2 1h body burdens, which is dissimilar from the model presented in PAHs. Anatase TiO2 presents a unique photo-induced toxic model that is different than that of established phototoxic compounds.
authors: Department of Biological Sciences, University of North Texas, 1511 W. Sycamore, Life Sciences Complex, Denton, TX 76203, United States.
authors: C M
authors: CM
authors: Mansfield
authors: Department of Biological Sciences, University of North Texas, 1511 W. Sycamore, Life Sciences Complex, Denton, TX 76203, United States.
authors: M M
authors: MM
authors: Alloy
authors: Department of Chemistry, University of North Texas, Department of Chemistry, 1417 W. Hickory St., Denton, TX 76203, United States.
authors: J
authors: J
authors: Hamilton
authors: Department of Chemistry, University of North Texas, Department of Chemistry, 1417 W. Hickory St., Denton, TX 76203, United States.
authors: G F
authors: GF
authors: Verbeck
authors: Department of Biological Sciences, Clemson University Institute of Environmental Toxicology, 509 Westinghouse Road, P.O. Box 709, Pendleton, SC 29670, United States.
authors: K
authors: K
authors: Newton
authors: Department of Biological Sciences, Clemson University Institute of Environmental Toxicology, 509 Westinghouse Road, P.O. Box 709, Pendleton, SC 29670, United States.
authors: S J
authors: SJ
authors: Klaine
authors: Department of Biological Sciences, University of North Texas, 1511 W. Sycamore, Life Sciences Complex, Denton, TX 76203, United States. Electronic address: aproberts@unt.edu.
authors: A P
authors: AP
authors: Roberts
mesh_terms: D000818:Animals; D003621:Daphnia / Q000187:drug effects*; D053768:Metal Nanoparticles / Q000633:toxicity*; D013472:Sunlight; D014025:Titanium / Q000633:toxicity*; D014874:Water Pollutants, Chemical / Q000633:toxicity*
chemical_list: D014874:Water Pollutants, Chemical; C009495:titanium dioxide; D014025:Titanium
keywords: Nanoparticles; Photo-induced toxicity; Titanium dioxide; Ultraviolet radiation