Ultraviolet (UV) radiation, or ultraviolet light, is an invisible form of light and energy given off primarily by the sun. Tanning booths and tanning beds are other sources of UV radiation. Frequent and intense exposure to UV radiation is the major environmental risk factor for melanoma, as well as for other forms of skin cancer. UV overexposure also causes sunburn, premature aging of the skin, and cataracts.

Intermittent exposure to intense sunlight is more strongly associated with the development of melanoma than continuous, daily sun exposure. This suggests that people who go on sunny vacations or participate in outdoor recreational activities should be especially careful in the sun.

Individuals who are more susceptible to the damaging effects of UV radiation are also at greater risk for developing melanoma. They include people with the following characteristics or conditions:

• Fair skin, red or blond hair, and blue eyes
• Poor tanning ability or an inability to tan; freckles easily
• A history of one or more severe, blistering sunburns before the age of 18
• Xeroderma pigmentosum, a rare, inherited condition associated with an inability to repair DNA damage caused by UV radiation. Individuals with this condition are at high risk for developing melanoma and must completely avoid any UV exposure.
• Numerous actinic keratoses, flat, pink, scaly spots that grow on sun-damaged skin of older, fair-skinned people. Actinic keratoses are precursors to skin cancers (especially squamous cell carcinomas of the skin) and are a result of heavy sun damage.
• Lentigines, flat, brown, sometimes large spots found most often on the face, arms, chest, back, and backs of the hands, and associated with aging or sun-damaged skin

People who use tanning beds, tanning booths, or sunlamps for cosmetic purposes increase their exposure to intense ultraviolet radiation and their risk for developing melanoma. Individuals who undergo psoralen and UVA (PUVA) therapy for psoriasis, particularly if they receive 250 treatments or more, are also at greater risk.¹

See Prevention for more information about ultraviolet radiation and how you can limit its damaging effects.