Effects of Sun Exposure
What are the Health Effects of Overexposure to the Sun?
UV Radiation has both positive and negative effects. Positive
effects of UV radiation include warmth, light, photosynthesis
in plants, and vitamin D synthesis in the body. UV radiation
also increases moods in people and kills pathogens (see
diagram). But overexposure to UV radiation has adverse health
effects. Overexposure to UV radiation is the primary environmental
risk factor in the development of UV-related adverse health
effects, which include diseases of the eye, immune suppression,
and skin cancers.
Children are most at risk for overexposure to UV radiation. With one in five Americans developing skin cancer, childhood education about sun protection is a vital step toward reducing risk and improving public health. Many studies have concluded that sun exposure, especially sunburn, during childhood appears to increase the risk of melanoma, the most serious form of skin cancer. Just one or two blistering sunburns in childhood can double a person's risk of developing melanoma later in life.
Children are of particular concern because they spend a lot of time outdoors. Perhaps most importantly, skin cancer and other UV-related adverse health effects are largely preventable if sun protection practices are followed early and consistently. Educating school staff and students about sun safety can prevent many health problems related to overexposure to the sun.
· Skin Cancer - According to the American Cancer Society (1999), skin cancer is the most common of all cancers. The incidence of skin cancer is greater than the incidence of breast, lung, prostate, colorectal, and kidney cancers combined. In the United States, about one million cases of skin cancer are diagnosed each year. One American dies every hour from skin cancer.
· Basal Cell and Squamous Cell Cancers - Basal cell carcinoma is the most commonly diagnosed skin cancer. Approximately 75 percent of skin cancers are basal cell carcinoma (American Cancer Society, 1997). Basal cell carcinoma usually appears on overexposed skin on the face, ears, lips, and particularly the nose. Rarely does basal cell carcinoma result in death, but it can spread and cause more serious health problems.
· Melanoma - Malignant melanoma is the most deadly of the three major skin cancers, causing approximately 75 percent of skin cancer deaths. Melanomas are usually dark brown or black mole-like patches with irregular edges (AAD, 1994). Melanoma is the most aggressive of the skin cancers. If not caught early, melanoma can spread to other parts of the body and can be fatal. However, when detected early, it is curable.
· Eye Damage - Sunlight is the primary source of UV radiation that can damage tissues of the eye. Results from dozens of studies suggest that spending long hours in the sun without eye protection increases the chances of developing eye diseases, including cataracts. The 1998 Journal of the American Medical Association reported that even low amounts of sunlight can increase the risk of developing eye disorders. The American Academy of Ophthalmology has cautioned that excess exposure to UV radiation may increase the incidence of cataracts.
· Photoaging/Wrinkling - A
very high percentage of age-associated cosmetic skin problems
can be attributed to sun (Levine, 1997). Chronic overexposure
to the sun changes the texture and weakens the elastic properties
of the skin. The epidermis, which is the outer layer of
the skin, thickens, becomes leathery, and wrinkles as a
result of sun exposure. The difference between skin tone,
wrinkles, or pigmentation on the underside of a person's
arm and the top side of the same arm illustrate the effects
of sun exposure on skin. In most cases, the top side of
the arm has had more exposure to the sun and shows greater
sun damage. Sun-induced skin damage causes wrinkles and
furrows, easy bruising, brown or "liver spots",
precancerous lesions (actinic keratoses), and potentially
skin cancer (Skin Cancer Foundation, 1992). Because photoaging
of the skin is cumulative, it is never too late for a person
to start a sun protection program.
· Immune System Suppression—Scientists believe sunburns can alter the distribution and function of disease-fighting white blood cells in humans for up to 24 hours after exposure to the sun. Repeated overexposure to UV radiation can cause more damage to the body's immune system. Mild sunburns can directly suppress the immune functions of human skin where the sunburn occurred, even in people with dark skin.