The dose-response relationship for tumourigenesis by UV radiation in the region 311 – 312 nm

Groups of hairless mice were irradiated daily with Philips TL01 UVB sources. This type of lamp has become available recently and was developed for UVB phototherapy of psoriasis. The TL01 emits radiation in a narrow band around 311 – 312 nm. Tumours developed on all animals. The dose-response relationship had practically the same shape as that found in a similar experiment with Westinghouse FS40 sunlamps; the tumour induction time appeared to be proportional to the daily dose to a power of −0.58. An additional experiment was performed with a TL01 from which the shorter wavelengths were filtered away. This reduced the carcinogenic effectiveness by a factor of 2.3. The potential of the filtered lamp for phototherapy of psoriasis is discussed.