Magazine article Consumers' Research Magazine

A Consumer;s Guide to Sun Protection: Sunscreen Isn't Enough

Magazine article Consumers' Research Magazine

A Consumer;s Guide to Sun Protection: Sunscreen Isn't Enough

Article excerpt

The tube screams at you--all day protection, broad spectrum coverage--so you pick it up and figure you and your kids are covered for a weekend at the beach. Not so fast, say scientists studying the effects of the sun on skin.

"There is nothing you can put on or over your skin that will allow you to stay in the sun for eight hours at a time," says Frank Gasparro, Ph.D., director of the photobiology laboratory at Yale University School of Medicine. Instead of imagining that coating ourselves with sunscreen is going to save us from skin cancer and sun-damaged skin, we need to change our sun habits and use sunscreens as a supplemental defense, instead of as the primary defense, he says.

After two decades of widescale sunscreen availability and a decade of education efforts, the incidence of skin cancers continues to rise. In the first update in 15 years, estimates for future skincancer cases of all kinds recently was revised from between 600,000 and 700,000 to a million or more per year--as many as for all other cancers combined, said Dr. Howard Koh, director of cancer prevention at Boston University Medical Center, at a recent American Academy of Dermatology (AAD) press conference. At that rate, one in six Americans will have a skin cancer sometime in their lives, says Koh.

Many theories are proposed as to why cancers are increasing. Some say increased leisure time allows people to spend more time in the sun; others that as the population ages the incidence of cancer naturally increases; others that we are just more aware of cancers and that therefore they are diagnosed more often. Whatever the reason, doctors are seeing more cases of skin cancer, and scientists have linked skin cancer, at least in part, to excessive sun exposure.

Fortunately, the vast majority of skin cancers (basal cell and squamous cell cancer account for 95% of all skin cancers) are the most curable. Even the more deadly melanoma has good cure rates when caught early. But dermatologists believe that, with a dose of caution, all kinds of skin cancer are avoidable to a great extent.

Why The Sun Is Dangerous

Two types of ultraviolet (UV) radiation, which are invisible to the eye, make it through the atmosphere to the surface of the earth--UV-A and UV-B. (A third type, UV-C is completely absorbed by the ozone layer before it reaches the earth's surface.) Both UV-A and UV-B are thought to play important roles in skin cancer development and skin aging.

UV-B rays are of a shorter wavelength than UV-A rays or visible light and the intensity of UV-B rays reaching the earth varies by season, time of day, and geography. It is most concentrated during the summer, at midday, and near the equator. Because of its shorter wavelength, it is more easily diffused and does not pass through glass but is between 800-1,000 times more potent in inducing erythema (skin reddening) than its longer wavelength sibling UV-A, according to the American Medical Association's Council on Scientific Affairs. Fortunately, a substantial portion of UV-B radiation is screened out in the atmosphere before it reaches the earth's surface. (See "Is It Getting Worse Under the Sun?" at page 14.)

UV-B penetrates into the top layer of skin where it damages DNA and stimulates thickening of the epidermis (the outer layer of skin) and production of melanin, a pigment which colors the skin, as your body attempts to protect itself from the radiation. In addition to being the most efficient agent in causing sunburn and tanning, there is a consensus among scientists that cumulative UV-B exposure is a major risk factor for skin cancer, particularly basal and squamous cell carcinomas.

Scientists have considered UV-B dangerous for decades, but as little as ten to twelve years ago UV-A was considered innocuous, according to Gasparro. Now scientists have raised concerns that perhaps UV-A is in some ways almost as dangerous as UV-B. …

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