Evaluation of skin-protective means against acute and chronic effects of ultraviolet radiation from sunlight.

Apart from erythema, sunlight triggers many biological processes such as photoaging, immune suppression and mutation of skin cells. Numerous epidemiological investigations have shown that sunlight is carcinogenic to humans, and the IARC classifies sunlight within group 1, which includes human carcinogens. Hereby, the UVB component of the solar spectrum presents the greatest degree of risk to the development of cutaneous neoplasms, but a certain carcinogenic potential of UVA has also been discussed. Practical steps to achieve optimal sun protection include avoidance of the sun during the peak hours of radiation, avoidance of photosensitizing drugs, use of photoprotective clothes and diligent application of broad-spectrum sunscreens. Of all recommended protective measures, sunscreens are often the most feasible to use, particularly during outdoor leisure, sport of aquatic activities. Therefore, the following chapter focuses mainly on the biological activity and efficacy of short- and long-term use of sunscreen products, but other recommended strategies of UV protection (such as intake of beta-carotene or application of liposomes) are critically evaluated as well. Although the short-term efficacy of sunscreens in the prevention of sunburn is undisputed, there is also some evidence that long-term use of sunscreens prevents the appearance of certain forms of skin cancer.