eng ara

Evaluates carcinogenic risks associated with human exposure to solar radiation and to ultraviolet radiation from medical and cosmetic devices, general illumination, and industrial sources. The main objective of the evaluation was to determine whether enough evidence is available to decide which segments of the radiation spectrum are responsible for its adverse effects. To this end, particular attention is given to data that shed light on the distinctive carcinogenic activity of ultraviolet A, B, and C radiation. More than 1,000 studies were critically assessed. The monograph has five main parts. The first provides a detailed evaluation of sources of human exposure, including an explanation of the many factors that complicate the interpretation of data. Although the sun remains the main source of exposure, the report notes the increased opportunity for both intentional and unintentional exposure created by the advent of artificial sources, including sunbeds and solaria, and numerous industrial processes. Welders are singled out as the largest occupational group exposed to artificial sources. The second and most extensive part assesses the large body of evidence implicating solar radiation and ultraviolet A, B, and C radiation in human cancer. The third part evaluates studies of cancer in animals, drawing upon data generated by a number of well-designed experiments using exposures to ultraviolet A, B, and C radiation. The fourth prt considers additional studies that shed light on the mechanisms by which human skin defends itself against the carcinogenic action of sunlight, the nature of DNA damage caused by exposure, alterations in immune function, and the question of whether exposure can activate viruses, including the human immunodeficiency virus. Concerning DNA damage, evidence supports the conclusion that ultraviolet A exposure for cosmetic purposes can result in measurable levels of damage. The results of these evaluations are presented in the final part, which concludes that solar radiation is carcinogenic to humans, causing cutaneous malignant melanoma and nonmelanocytic skin cancer. All three segments of the radiation spectrum were classified as probably carcinogenic to humans. Use of sunlamps and sunbeds entails exposures that are probably carcinogenic to humans. The carcinogenicity of exposure to fluorescent lighting could not be determined on the basis of available data. Studies of topical sunscreens are reviewed in an appendix, which concludes that, although effective in preventing sunburn, little is known about their protective value against harmful immunological changes, photo-ageing, or skin cancer.

DC.IARC

WHODOC

WHO monograph

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