Health Impacts of Exposure to Ultraviolet (UV) Radiation
Exposure to ultraviolet radiation (UV), from any source, damages body tissues through prolonged or intense exposure. Tanning is the body's protective response against injury to the skin from UV exposure.
When exposed to UV radiation, skin cells in the top layer of skin work to repair the damage and protect the skin. The body produces and releases more melanin, a skin pigment, to absorb the UV. This causes the skin to darken.
The Two Types of UV Radiation that Cause Tanning: UVA and UVB
UVA causes immediate, short-term tanning – a slight darkening of the melanin that is already in the skin. The amount of tanning increases according to the skin's natural darkness and previous amount of tanning. Repeated UVA exposure leads to premature skin aging. This includes wrinkling, sagging, blemishes and age spots, as well as precancerous skin changes (e.g., red, rough, scaling spots called “actinic keratoses”).
UVB causes delayed, but long-term, tanning by stimulating the production of more melanin. In recent years, tanning bed lamps have been produced that emit higher levels of UVB to mimic the solar spectrum and enhance the tanning process.
Both UVA and UVB can cause sunburn, an often painful inflammation caused by an increase in blood flow beneath the skin. Also, the sun's UV rays increase a person's risk of cataracts and other eye problems.
Skin cancer is the most common type of cancer in North America. According to the Canadian Dermatology Association, one Canadian dies of skin cancer about every seven hours.
The good news is that skin cancer is one of the most preventable cancers, by avoiding exposure to ultraviolet radiation. There are three main types of UV-related skin cancer (carcinoma). The first two, basal cell carcinoma and squamous cell carcinoma are usually are very treatable, with high survival rates. The third type, malignant melanoma, is less common, but the most dangerous.
The amount of UV exposure a person gets over time and the number of sunburns is linked to developing skin cancer later in life. Children and adolescents who spend a lot of time in the sun are especially vulnerable.
Basal cell carcinoma (80% of all skin cancers) is the most common, but the least serious kind of skin cancer, growing slowly and rarely spreading.
Squamous cell carcinoma (15% of all skin cancers) is more serious than basal cell carcinoma because it does spread to vital organs, although slowly.
Malignant melanoma (5%) can spread quickly from the outer layer of the skin through the lymph nodes or blood to internal organs. Unlike many cancers, the incidence of melanoma is increasing. The Canadian Cancer Society states on its Melanoma website that “based on 2010 estimates:
- About 1 in 57 Canadian men is expected to develop melanoma during his lifetime and 1 in 227 will die from it
- About 1 in 74 Canadian women is expected to develop melanoma during her lifetime and 1 in 456 will die from it.”
Because lifetime exposure to UV increases one's risk of skin cancer, the World Health Organization recommends that no one under the age of 18 should use a tanning bed. It has found that ultraviolet (UV) radiation from indoor tanning equipment is a proven carcinogen (cancer-causing agent), and the risk of melanoma increases by 75% when tanning bed use starts before 35 years of age.