Differences in narrow-band ultraviolet B and broad-spectrum ultraviolet photocarcinogenesis in lightly pigmented hairless mice.

The carcinogenic effect of 4 ultraviolet (UV) sources was studied in lightly pigmented hairless mice. Two narrow-band UV sources, Philips TL01 and Philips TL12 with a Tempax filter, and two broad-spectrum UV sources, Philips TL12 and Bellarium S, were used. Exposure doses were calculated from the CIE erythema action spectrum. Four groups of mice (n = 20) were exposed to a nonerythemogenic dose (low dose), and 4 groups were exposed to an erythemogenic dose (high dose) of each of the 4 UV sources. One group (control) was not irradiated. The mice in the 4 low-dose groups were all exposed to 0.6 basic minimal erythema doses (B-MED) 5 days/week, and all the mice in the high-dose groups to 1.2 B-MED 5 days/week. After 16 weeks of acclimatization, the doses were doubled. Bellarium S and Philips TL12 were equally carcinogenic in the low-dose regimen and the high-dose regimen. Mice exposed to Philips TL12 with a Tempax filter developed tumors significantly earlier compared with Bellarium and Philips TL12. Philips TL01 was more carcinogenic than any of the other UV sources. Equally erythemogenic doses calculated from the CIE erythema action spectrum seem to be more carcinogenic when derived from narrow-band UVB sources than from broad-band UV sources.