[Favourable and unfavourable effects of exposure to sunlight].

The negative effects of sunlight include the more frequent or earlier development of skin cancer and degenerative changes in the skin, and the occurrence ofphotodermatoses. - However, sunlight also has a favourable effects; specifically, it may inhibit the development and progression of diseases of the bones, muscles and skin, ofvarious malignancies (carcinoma of the prostate, breast, colon and ovary, non-Hodgkin lymphoma), and may prevent certain autoimmune diseases, particularly multiple sclerosis. - This protective effect is ascribed to an increased synthesis of vitamin D, which is important for bone metabolism and is also able to regulate cell proliferation and differentiation, apoptosis, tumour invasion and angiogenesis. - The possible consequence of this new information is that public information regarding exposure to sunlight must continue to include a warning against excessive exposure to the sun, while at the same time stimulating regular although limited sunbathing.