title: Effects of four commonly used UV filters on the growth, cell viability and oxidative stress responses of the Tetrahymena thermophila.
abstract: UV filters are increasingly used in sunscreens and other personal care products. Although their residues have been widely identified in aquatic environment, little is known about the influences of UV filters to protozoan. The growth inhibition effects, cell viability and oxidative stress responses of four commonly used UV filters, 2-ethylhexyl 4-methoxycinnamate (EHMC), benzophenone-3 (BP-3), 4-methyl-benzylidene camphor (4-MBC) and octocrylene (OC), to protozoan Tetrahymena thermophila were investigated in this study. The 24-h EC50 values with 95% confidence intervals for BP-3 and 4-MBC were 7.544 (6.561-8.675) mg L(-1) and 5.125 (4.874-5.388) mg L(-1), respectively. EHMC and OC did not inhibit the growth of T. thermophila after 24h exposure at the tested concentrations. The results of cell viability assays with propidium iodide (PI) staining were consistent with that of the growth inhibition tests. As for BP-3 and 4-MBC, the relatively higher concentrations, i.e. of 10.0 and 15.0 mg L(-1), could lead to the cell membranes impairment after 4h exposure. With the increase of the exposure time to 6h, their adverse effects on cell viability of T. thermophila were observed at the relatively lower concentration groups (1.0 mg L(-1) and 5.0 mg L(-1)). In addition, it is noticeable that at environmentally relevant concentration (1.0 μg L(-1)), BP-3 and 4-MBC could lead to the significant increase of catalase (CAT) activities of the T. thermophila cells. Especially for the BP-3, the oxidative injuries were further confirmed by the reduction of glutathione (GSH) content. It is imperative to further investigate the additive action of UV filters and seek other sensitive endpoint, especially at environmentally relevant concentration.
authors.affiliation: School of Environmental Science and Engineering, Shanghai Jiao Tong University, Shanghai 200240, China; School of Resource and Environment, Ningxia University, Yinchuan 750021, China.
authors.forename: Li
authors.initials: L
authors.lastname: Gao
authors.forename: Tao
authors.initials: T
authors.lastname: Yuan
authors.forename: Chuanqi
authors.initials: C
authors.lastname: Zhou
authors.forename: Peng
authors.initials: P
authors.lastname: Cheng
authors.forename: Qifeng
authors.initials: Q
authors.lastname: Bai
authors.forename: Junjie
authors.initials: J
authors.lastname: Ao
authors.forename: Wenhua
authors.initials: W
authors.lastname: Wang
authors.forename: Haimou
authors.initials: H
authors.lastname: Zhang
mesh_terms: D000179:Acrylates / Q000633:toxicity; D001577:Benzophenones / Q000633:toxicity; D002164:Camphor / Q000031:analogs & derivatives / Q000633:toxicity; D002470:Cell Survival; D002934:Cinnamates / Q000633:toxicity; D018384:Oxidative Stress; D013473:Sunscreening Agents / Q000633:toxicity*; D016808:Tetrahymena thermophila / Q000187:drug effects* / Q000502:physiology; D014466:Ultraviolet Rays; D014874:Water Pollutants, Chemical / Q000633:toxicity*
chemical_list: D000179:Acrylates; D001577:Benzophenones; D002934:Cinnamates; D013473:Sunscreening Agents; D014874:Water Pollutants, Chemical; C516303:ethylhexyl methoxycinnamate; C088673:octocrylene; C063318:4-methoxycinnamic acid; D002164:Camphor; C038939:enzacamene; C005290:oxybenzone
keywords: 4-Methyl-benzylidene camphor; Benzophenone-3; Cell viability; Environmentally relevant concentration; Growth inhibition; Oxidative stress