UltraViolet Radiation (Sunlight), Sunburns, Sun Exposure and Your Health
Health Effects of Overexposure to the Sun
Most people love the sun, and spend increasing amounts of time outside - working, playing, exercising - often in clothing that exposes a lot of skin to the sun. Most people are now aware that too much sun has been linked to skin cancer, but few know the degree of risk posed by overexposure, and fewer are aware that the risks go beyond skin cancer. Recent medical research has shown that overexposure to the sun's ultraviolet (UV)
radiation can contribute to serious health problems.
This page provides a quick overview of the major problems linked to UV exposure: skin cancer (melanoma and non-melanoma), other skin problems, cataracts, and immune system suppression. Understanding these risks and taking a few sensible precautions (described in other UV Index fact sheets) will help you to enjoy the sun while lowering your chances of sun-related health problems later in life.
FACTS AND FIGURES
- There has been an 1,800 percent rise in malignant melanoma since 1930.
- One American dies of skin cancer every hour.
- One in five Americans develops skin cancer.
- People get 80 percent of their lifetime sun exposure by the age of 18.
|UVA vs. UVB|
|There are two types of UV radiation, UVA and UVB. UVB is usually associated with sunburn while UVA is recognized as a deeper penetrating radiation.|
The most obvious result of too much sun is sunburn, which involves skin redness and sometimes tenderness, swelling, blistering, fever, and nausea. Although some skin types prevent individuals from burning, everyone is at risk for other UV-related health effects.
Some people may develop bumps, hives, blisters, or red blotchy areas as an allergic reaction to sun exposure. Certain drugs, perfumes, and cosmetics also can make some people sensitive to the sun.
In the long run, too much exposure to the sun can change your skin's texture, giving it a tough, leathery appearance. The sun also can cause discolorations in skin tone including red, yellow, gray, or brown spots.
Over time, exposure to the sun and severe sunburns can lead to skin cancer. The most common places for skin cancer to develop are on those body parts exposed to the sun such as the face, neck, ears, forearms, and hands.
The three main types of skin cancer are basal cell carcinoma, squamous cell carcinoma, and malignant melanoma.
- Basal cell carcinomas are tumors that usually appear as small, fleshy bumps or nodules.
- Squamous cell carcinomas appear as nodules or as red, scaly patches.
- Malignant melanomas may appear without warning as a dark mole or other dark spot in the skin.
All three types can be curable if you detect them in their early stages. To help recognize potential problems, conduct periodic self-examinations and watch for growths that meet one of the 'ABCDs' of melanoma.
Melanoma, the most serious form of skin cancer, is also one of the fastest growing types of cancer in the U.S. Many dermatologists believe there may be a link between childhood sunburns and malignant melanoma later in life. Melanoma cases in the U.S. have almost doubled in the past two decades, with at least 32,000 new cases and 6,900 deaths estimated for 1994 alone. The rise in melanoma cases and deaths in America is expected to continue.
- Cure Rate
- Melanoma can spread to other parts of the body quickly, but when detected in its earliest stages it is almost always curable. If not caught early, melanoma is often fatal.
- What to Watch For
- Melanoma begins as an uncontrolled growth of pigment-producing cells in the skin. This growth leads to the formation of dark-pigmented malignant moles or tumors, called melanomas. Melanomas may suddenly appear without warning, but may also develop from or near a mole. For that reason, it is important to know the location and appearance of moles on the body so any change will be noticed. Melanomas are found most frequently on the upper backs of men and women, and the legs of women, but can occur anywhere on the body.
Be aware of any unusual skin condition, especially a change in the size or color of a mole or other darkly or irregularly pigmented growth or spot; scaliness, oozing, bleeding, or change in the appearance of a bump or nodule; spread of pigment from the border into surrounding skin; and change in sensation including itchiness, tenderness, or pain.
Unlike melanoma, non-melanoma skin cancers are rarely fatal. Nevertheless, they should not be taken lightly. Untreated, they can spread, causing more serious health problems. An estimated 900,000 Americans developed non-melanoma skin cancers in 1994, while 1,200 died from the disease.
There are two primary types of non-melanoma skin cancers:
- Basal Cell Carcinomas are tumors of the skin which usually appear as small, fleshy bumps or nodules on the head and neck, but can occur on other skin areas as well. It is the most common skin cancer found among fair-skinned people. Basal cell carcinoma does not grow quickly, and rarely spreads to other parts of the body. However, it can penetrate below the skin to the bone and cause considerable local damage.
- Squamous Cell Carcinomas are tumors which may appear as nodules or as red, scaly patches. The second most common skin cancer found in fair-skinned people, squamous cell carcinoma is rarely found in darker-skinned people. This cancer can develop into large masses, and unlike basal cell carcinoma, it can spread to other parts of the body.
- Cure Rate
- These two non-melanoma skin cancers have high cure rates - as high as 95 percent if detected and treated early. The key is to watch for signs and to detect the cancer in its early stages.
- What to Watch For
- Basal cell carcinoma tumors usually appear as slowly growing, raised, translucent, pearly nodules which, if untreated, discharge pus, and sometimes bleed. Squamous cell carcinomas usually are raised, red or pink scaly nodules or wart-like growths that form pus in the center. They typically develop on the edge of the ears, the face, lips, mouth, hands, and other exposed areas of the body.
|Asymmetry: One half of the growth doesn't match the other half. |
|Border irregularity: The edges of the growth are ragged, notched, or blurred. |
|Color: The pigmentation of the growth is not uniform. Shades of tan, brown, and black are present. Dashes of red, white, and blue also may appear. |
|Diameter: Any growth greater than 6 millimeters (about the size of a pencil eraser) is cause for concern. |
If you notice any changes in the appearance of moles or freckles, contact a dermatologist.
These sun-induced skin growths occur on body areas exposed to the sun. The face, hands, forearms, and the "V" of the neck are especially susceptible to this type of blemish. They are pre-malignant, but if left untreated, actinic keratoses can become malignant. Look for raised, reddish, rough-textured growths. See a dermatologist promptly if you notice these growths.
Cataracts are a form of eye damage, a loss of transparency in the lens which clouds vision. Left untreated, cataracts can rob people of vision. Research has shown that UV radiation increases the likelihood of certain cataracts. Although curable with modern eye surgery, cataracts diminish the eyesight of millions of Americans, and necessitate millions of dollars of eye surgery each year. Other kinds of eye damage include: pterygium (tissue growth on the white of the eye that can block vision), skin cancer around the eyes, and degeneration of the macula (the part of the retina near the center, where visual perception is most acute). All of these problems could be lessened with proper eye protection from UV radiation.
The American Academy of Ophthalmology has cautioned that excess exposure to UV radiation can cause a painful burn of the cornea. Chronic eye exposure to UV radiation may increase the incidence of the development of spots that could result in blindness.
No matter what your skin type or susceptibility to burns, sun exposure can damage your immune system and make your body more vulnerable to infections and cancers. Diseases, such as herpes simplex (cold sores), chicken pox, and lupus, can become worse with sun exposure.
Scientists have found that sunburn 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 exposure to UV radiation may cause more long-lasting 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.
The UV Index, developed by the National Weather Service and the Environmental Protection Agency
, provides a forecast of the expected risk of overexposure to the sun and indicates the degree of caution you should take when working, playing, or exercising outdoors. The UV Index predicts exposure levels on a 0-10+ scale, where 0 indicates a low risk of overexposure, and 10+ means a very high risk of overexposure. Calculated on a next-day basis for dozens of cities across the U.S. by the National Weather Service, the UV Index takes into account clouds and other local conditions that affect the amount of UV radiation reaching the ground in different parts of the country.
Looking for more detail?
The UV index page
How the UV index is calculated
To learn more about the UV Index and how to protect yourself from overexposure to the sun's UV rays, call EPA's Stratospheric Ozone Hotline at (800) 296-1996. Hotline staff can supply you with other fact sheets in this series, as well as other useful information.