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 l ightly pigmented hairless mice. Two narrow-band UV sources, Philips TL 01 and Philips TL12 with a Tempax filter, and two broad-spectrum UV so urces, Philips TL12 and Bellarium S, were used. Exposure doses were ca lculated from the CIE erythema action spectrum. Four groups of mice (n = 20) were exposed to a nonerythemogenic dose (low dose), and 4 group s were exposed to an erythemogenic dose (high dose) of each of the 4 U V sources. One group (control) was not irradiated. The mice in the 4 l ow-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-M ED 5 days/week. After 16 weeks of acclimatization, the doses were doub led. 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 w ith Bellarium and Philips TL12. Philips TL01 was more carcinogenic tha n any of the other UV sources. Equally erythemogenic doses calculated from the CIE erythema action spectrum seem to be more carcinogenic whe n derived from narrow-band UVB sources than from broad-band UV sources .