Long-term health risk to the skin of ultraviolet radiation.

The major well-proven long-term health risks of excessive exposure to ultraviolet (UV) radiation relate to the skin. Premalignant skin lesions are seen very much earlier in white skinned populations exposed to excessive sunlight, and over time these same individuals develop larger numbers of all of the three major skin cancers than individuals who do not experience excessive UV exposure. These three skin cancers are squamous cell carcinoma (SCC), basal cell carcinoma (BCC), and malignant melanoma. In the case of SCC the major aetiological pattern is chronic long-term exposure, but for BCCs the pattern appears to be slightly different with short-term burning episodes being more important. In the case of melanomas, there is evidence that for the 4 main types of melanomas, the pattern of excess UV exposure which is most injurious varies.