Mon, June 22, 2009

Ultraviolet Radiation - What You Need To Know

Ultraviolet radiation and it’s role in conditions such as premature skin aging and skin cancers.

The sun emits ultraviolet A (long-wave), ultraviolet B (shortwave), and ultraviolet C (even shorter wave) rays. Most UVC is absorbed by the ozone layer and does not reach the earth, however, both UVA and UVB penetrate the atmosphere and play an important role in conditions such as premature skin aging, eye damage (including cataracts), and skin cancers. They also suppress the immune system, reducing your ability to fight off these and other maladies.

UV Radiation and Skin Cancer
By damaging the skin's cellular DNA, excessive UV radiation produces genetic mutations that can lead to skin cancer. Both the U.S. Department of Health and Human Services and the World Health Organization have identified UV as a proven human carcinogen. UV radiation is considered the main cause of nonmelanoma skin cancers, including basal cell carcinoma (BCC) and squamous cell carcinoma (SCC). These cancers strike more than a million and more than 250,000 Americans, respectively, each year. Many experts believe that, especially for fair-skinned people, UV radiation also frequently plays a key role in melanoma, the deadliest form of skin cancer, which kills more than 8,000 Americans each year.

UVA
Most of us are exposed to large amounts of UVA throughout our lifetime. UVA rays account for up to 95 percent of the UV radiation reaching the Earth's surface. Although they are less intense than UVB, UVA rays are 30 to 50 times more prevalent. They are present with relatively equal intensity during all daylight hours throughout the year, and can penetrate clouds and glass.
UVA is the dominant tanning ray, and we now know that tanning, whether outdoors or in a salon, causes cumulative damage over time. A tan results from injury to the skin's DNA; the skin darkens in an imperfect attempt to prevent further DNA damage. These imperfections, or mutations, can lead to skin cancer.
Tanning booths primarily emit UVA. The high-pressure sunlamps used in tanning salons emit doses of UVA as much as 12 times that of the sun. Not surprisingly, people who use tanning salons are 2.5 times more likely to develop squamous cell carcinoma, and 1.5 times more likely to develop basal cell carcinoma. According to recent research, first exposure to tanning beds in youth increases melanoma risk by 75 percent.

UVB
UVB, the chief cause of skin reddening and sunburn, tends to damage the skin's more superficial epidermal layers. It plays a key role in the development of skin cancer and a contributory role in tanning and photoaging. Its intensity varies by season, location, and time of day. The most significant amount of UVB hits the U.S. between 10 AM and 4 PM from April to October. However, UVB rays can burn and damage your skin year-round, especially at high altitudes and on reflective surfaces such as snow or ice, which bounce back up to 80 percent of the rays so that they hit the skin twice. UVB rays do not significantly penetrate glass.

Protective Measures
Since both UVA and UVB are harmful, you need protection from both kinds of rays. To make sure you're getting effective UVA as well as UVB coverage, look for a sunscreen with an SPF of 15 or higher, plus some combination of the following UVA-screening ingredients: stabilized a avobenzone, ecamsule (a.k.a. Mexoryl™), oxybenzone, titanium dioxide, and zinc oxide. You may see the phrases multi spectrum, broad spectrum or UVA/UVB protection on sunscreen labels, and these all indicate that some UVA protection is provided.

Preventative Measures

Seek the shade, especially between 10 AM and 4 PM

Do not burn

Avoid tanning and UV tanning booths

Cover up with clothing, including a broad-brimmed hat and UV-blocking sunglasses

Use a sunscreen with an SPF of 15 or higher every day

Apply 1 ounce (2 tablespoons) of sunscreen to your entire body 30 minutes before going outside. Reapply every two hours, or immediately after swimming or excessive sweating

Keep newborns out of the sun. Sunscreens should be used on babies over the age of six months

Examine your skin head-to-toe every month

See your physician every year for a professional skin exam

Information provided by the Skin Cancer Foundation

Email this • Print This • Subscribe to this feed • Share on Facebook • Twit This! • Save to del.icio.us • Digg This! • Technorati Links • Permalink

Back to Archives -->