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An Evaluation of the Potential Phototoxicity of CeO2 Nanoparticles in Retinal Pigment Epithelial Cells in-vitro
Pantlin, L., J. Ortenzio, V. Holub, L. Degn, R. Zucker, AND W. Boyes. An Evaluation of the Potential Phototoxicity of CeO2 Nanoparticles in Retinal Pigment Epithelial Cells in-vitro. Presented at Society of Toxicology Meeting, Phoenix, AZ, March 23 - 27, 2014.
Cerium dioxide (CeO2) engineered nanoparticles (NP) are used as fuel-borne catalysts in off-road diesel engines, which can lead to exhaust emissions of respirable CeO2 NP. Other metal oxides may act as photo-catalysts which induce the generation of free radicals upon exposure to UV radiation or visible light. The current study tested the hypothesis that CeO2 NP would cause a dose-dependent phototoxic reaction in human-derived retinal pigment epithelial cells (ARPE-19) after UV exposure. Two samples of CeO2 NP (Alfa Aesar, 36-99 nm; NanoAmor, 6-60 nm) were suspended in cell culture media with 10% fetal bovine serum (FBS) at concentrations: 0, 3, 10, 20, 30, 55, 100ug/ml or 20ug/m1 TiO2 NP (Degussa P25; positive control) and administered to ARPE-19 cells grown in 24-well plates. Plates were either exposed to UV radiation (t=90min) or kept in the dark. After 24hrs, cell viability was determined with a calcein-AM/propidium iodide stain. Exposure to higher concentrations of CeO2 NP reduced cell viability in dark conditions. Exposure to UV light (290-400nm) reduced cell viability in Ce02 NP compared to dark plates. When a 2.5% CuSO4 solution filter restricted exposure to the UVA (320-400nm) range; there was no difference in viability between UVA exposed cells and dark controls. The results showed significant effects of irradiation (F(2,165) = 3.87,p = 0.02) and between the cerium samples (F(2,165) = 1.91, p < .0001) such that CeO2 NP NanoAmor participated in phototoxic reactions with UVB, but not UVA wavelengths. Both samples of CeO2 NP were less potent phototoxicants than TiO2 NP. Dark-field microscopy confirmed CeO2 NP uptake into ARPE-19 cells. At concentrations higher than 3ug/m1 CeO2NP formed visible intracellular agglomerates, which were spatially arranged around the nucleus and associated with the endoplasmic reticulum and mitochondria. Thus, CeO2 NP were taken up into ARPE-19 cells in culture, and showed slight phototoxicity in response to UV irradiation between 290-320 nm. This does not reflect EPA policy.
This abstract will be presented at the Society of Toxicology meeting March 23-27, 2014, Phoenix, AZ
Record Details:Record Type: DOCUMENT (PRESENTATION/ABSTRACT)
Organization:U.S. ENVIRONMENTAL PROTECTION AGENCY
OFFICE OF RESEARCH AND DEVELOPMENT
NATIONAL HEALTH AND ENVIRONMENTAL EFFECTS RESEARCH LAB
TOXICOLOGY ASSESSMENT DIVISION