Cytotoxicity and genotoxicity of UVA irradiation in Chinese hamster ovary cells measured by specific locus mutations, sister chromatid exchanges and chromosome aberrations

— The increasing use of artificial UVA (320-400 nm) suntanning devices has brought attention to possible hazardous effects of UVA. In contrast with earlier studies, several groups recently have described that UVA possibly is mutagenic. In this paper we evaluate the genotoxic properties of broad band UVA using CHO cells and three different assays: specific locus (HGPRT) mutations, chromosome aberrations, and sister chromatid exchanges (SCEs). The UVA-source was an UVASUN 2000 S (Mutzhas), emitting UVA above 340 nm. The survival curve of the cells exhibited a shoulder up to 200 kJ/m2, that was followed by exponential killing at higher fluences. Mutations were induced linearly in the fluence range from 0-200 kJ/m2 (P < 0.001) to a level seven fold higher than the spontaneous, followed by a decrease at fluences above 300 kJ/m2. Over the total range of tested fluences (0-300 kJ/m2) a linear dose-response relationship was observed for UVA-induced SCEs (P < 0.001). A significantly higher percentage of the cells showed chromosomes with aberrations at the higher levels of exposure (200, 300 and 400 kJ/m2), but no dose response was demonstrated. Our results confirm recent findings showing that UVA is mutagenic in mammalian cells and suggest that UVA exposure may contribute to the total burden of genetic damage caused by exposure to ultraviolet light.