title: Carcinogenic and melanogenic effects of a filtered metal halide UVA source and a tubular fluorescent UVA tanning source with or without additional solar-simulated UV radiation in hairless mice.
abstract: The carcinogenic and melanogenic effects of a filtered metal halide source (UVASUN) that emits UV radiation in a range from 340 to 400 nm and a bank of Philips TL 09R tubes (TL 09) emitting in a range from 310 to 400 nm were studied in lightly pigmented hairless hr/hr C3H/Tif mice. Both the carcinogenic effect of the two UVA radiation sources alone and in combination with a UV source, consisting of one Philips TL 12 and five Bellarium-S SA-1-12 tubes emitting radiation somewhat similar to the UV part of the solar spectrum (SOLAR UV), were investigated. Finally, the melanogenic effect of exposure to the two UVA sources were studied. The mice were exposed to the UVA sources 30 min/day 5 days/week, in equal erythemogenic doses, calculated by using the Commission Internationale de l'Eclairage human erythema action spectrum. Equal erythemogenic doses of TL 09 and UVASUN induced the same degree of skin pigmentation, but skin tumor development was enhanced in mice exposed to TL 09 compared with UVASUN (P < 0.0005). For all but one tumor, endpoint pretreatment with TL 09 or UVASUN for 91 days did not influence tumor development during subsequent exposure to SOLAR UV radiation 10 min/day, 4 days/week. Exposure to the two UVA radiation sources after 91 days of SOLAR UV exposure significantly enhanced skin tumor development. Overall, the data on the interaction between exposure to the UVA sources and SOLAR UV indicated that the risk of SOLAR UV-induced carcinogenesis was independent of the type of prior-UVA exposure and post-UVA exposure.
mesh_terms: D000818:Animals; D004307:Dose-Response Relationship, Radiation; D004890:Erythema / Q000209:etiology / Q000503:physiopathology; D006801:Humans; D008543:Melanins / Q000096:biosynthesis*; D051379:Mice; D008812:Mice, Hairless; D009381:Neoplasms, Radiation-Induced / Q000209:etiology / Q000473:pathology*; D012867:Skin / Q000378:metabolism / Q000528:radiation effects*; D012878:Skin Neoplasms / Q000209:etiology / Q000473:pathology*; D012880:Skin Pigmentation / Q000528:radiation effects*; D013472:Sunlight; D014466:Ultraviolet Rays
chemical_list: D008543:Melanins