Modification of 5-methoxypsoralen phototumorigenesis by UVB sunscreens: a statistical and histologic study in the hairless albino mouse.
Sunscreen preparations containing 5-methoxypsoralen at 25 micrograms/ml and 50 micrograms/ml, and the appropriate vehicle only, sunscreen only, and 5-methoxypsoralen only controls, were assessed for tumorigenic potential in hairless albino mice exposed to solar simulated radiation for a period of 44-46 weeks. Some animals were observed for a 15 week post-irradiation period. A wide range of statistical analyses has shown that, during the course of irradiation, the inclusion of sunscreens eliminates the enhancement of phototumorigenesis and malignancy that is normally observed with 5-methoxypsoralen. There was, however, some indication of increased risk at the end of the postirradiation follow-up period. Possible reasons for the protective effect of the sunscreens and the relevance of these data to the assessment of human risk are discussed.
Young
A R
AR
Department of Photobiology, United Medical School of Guy's, London.
Gibbs
N K
NK
Magnus
I A
IA
D000078223:5-Methoxypsoralen; D000818:Animals; D005260:Female; D008730:Methoxsalen / Q000633:toxicity*; D051379:Mice; D008812:Mice, Hairless; D009381:Neoplasms, Radiation-Induced / Q000209:etiology / Q000473:pathology / Q000517:prevention & control*; D014677:Pharmaceutical Vehicles / Q000494:pharmacology; D012306:Risk; D012737:Sex Factors; D012878:Skin Neoplasms / Q000139:chemically induced* / Q000209:etiology / Q000517:prevention & control; D013473:Sunscreening Agents / Q000494:pharmacology / Q000633:toxicity*; D013997:Time Factors; D014466:Ultraviolet Rays / Q000009:adverse effects
D014677:Pharmaceutical Vehicles; D013473:Sunscreening Agents; D000078223:5-Methoxypsoralen; D008730:Methoxsalen