title: Degradation of nonylphenol polyethoxylates by ultraviolet B irradiation and effects of their products on mammalian cultured cells.
abstract: Nonylphenol polyethoxylates (NPEOs) are widely used as non-ionic surfactants and their biodegradation products such as 4-n-nonylphenol are stable and have been demonstrated to be cytotoxic. In the aquatic environment, these compounds are usually exposed to sunlight, and while the correlation between the biodegradation of NPEOs and changes in cytotoxicity has been reported, the relationship between the photodegradation of NPEOs and cytotoxicity has not. In this study, we investigated the degradation of NPEO by ultraviolet (UV) irradiation, especially UVB irradiation, and the effects on mammalian cell lines. NPEO with a smaller number of ethylene oxide (EO) units showed greater cytotoxicity. Although NPEO (10) completely inhibited the proliferation of the cells, NPEO (70) showed no toxicity. UVB irradiation significantly induced a shortening of the side chain, which was due to the production of ROS. The EO side chain of NPEO (10), was gradually degradated, but that of NPEO (70) was degradated near the benzene ring. Furthermore, the degradation of the benzene ring was more effective in NPEO (70) than NPEO (10). The toxicity of NPEO (10) in cultured cells decreased following UVB irradiation, whereas that of NPEO (70) was induced after UVB irradiation at 500 J/cm2 and disappeared at 1000 J/cm2. This might be due to the production of NPEO with a short side chain and 4-n-nonylphenol by the degradation of EO and due to the degradation of the benzene ring at higher doses of UVB irradiation. This study shows the significance of UV exposure to the degradation of alkylphenol polyethoxylates in the environment.
authors.affiliation: Laboratory of Radiation Biology, Graduate School of Nutritional and Environmental Sciences, University of Shizuoka, 52-1 Yada, Shizuoka-shi 422-8526, Japan. gotor@sea.u-shizuoka-ken.ac.jp
authors.forename: Rensuke
authors.initials: R
authors.lastname: Goto
authors.forename: Toru
authors.initials: T
authors.lastname: Kubota
authors.forename: Yuko
authors.initials: Y
authors.lastname: Ibuki
authors.forename: Kazuhiko
authors.initials: K
authors.lastname: Kaji
authors.forename: Ayako
authors.initials: A
authors.lastname: Goto
mesh_terms: D000818:Animals; D002455:Cell Division / Q000187:drug effects; D004307:Dose-Response Relationship, Radiation; D005026:Ethylene Glycols / Q000528:radiation effects* / Q000633:toxicity*; D006801:Humans; D019169:Jurkat Cells / Q000187:drug effects / Q000528:radiation effects; D051379:Mice; D041681:NIH 3T3 Cells / Q000187:drug effects / Q000528:radiation effects; D010782:Photolysis; D017382:Reactive Oxygen Species / Q000378:metabolism; D014466:Ultraviolet Rays
chemical_list: D005026:Ethylene Glycols; D017382:Reactive Oxygen Species; C021754:terics