Sunscreens: some don't block rays as well as they claim.(Evaluation)

The phrase "with sunscreen" seems as ubiquitous at the drugstore as "low fat" is at the supermarket. Sunscreen is now in moisturizers, lip balms, shampoos, hair-styling products, insect repellents, and makeup. Rit, the dye brand, has created colorless sunscreen you wash into clothes. In Europe, Procter & Gamble plans to sell sunscreen-soaked Pampers Sunnies UV Wipes, ostensibly for places on a baby where the sun does shine.

There's a good reason for this newfound stress on products to protect the skin. More than 1 million skin cancers are expected to be diagnosed in the U.S. this year--almost half of all cancers diagnosed. The vast majority will be slow-growing basal- and squamous-cell carcinomas. Those can be successfully treated or surgically removed, though they can be fatal if ignored. Some 51,400 cases will be malignant melanoma, more lethal than basal- or squamous-cell cancer. This year, an estimated 9,800 Americans will die of some form of skin cancer.

The prevalence of skin cancer is attributable in part to a history of unprotected--or underprotected--sun exposure. Sunlight is linked to all types of skin cancers, and sunscreen has been shown to prevent squamous-cell lesions. Sun exposure associated with severe sunburns increases the risk of melanoma. Although research has yet to prove that sunscreen helps prevent the disease, the evidence is compelling. Almost all dermatologists recommend using sunscreen as part of an overall skin-protection program, which focuses first on limiting direct sun and wearing protective clothing.

Yet, as a 1997 survey found, only about half of white women and a third of white men in the U.S. use sunscreen regularly when sunbathing. And research by the American Cancer Society, among others, has determined that even people who use sunscreen may use it incorrectly: They may not apply enough, may not allow enough time to let it soak in, or may not reapply it after swimming, toweling off, or sweating.

Some experts believe that people may also bake too long, lulled into a false sense of security by a high sun-protection factor (SPF). The need for proper application and for watching the clock was underlined by an American Cancer Society study of teenagers in 1998. The youngsters in that study experienced their worst sunburn of the summer when using sunscreens with an SPF of at least 15.

Sunlight does provide at least one benefit: It stimulates skin to make vitamin D, which helps maintain bone strength. Fortunately, for many people, just 5 to 10 minutes of unscreened sun exposure two or three times a week during summer lets the body store enough vitamin D for the year. Because the skin's ability to make the vitamin declines with age, people older than 50 may need more sun or a vitamin-D supplement.

RESULTS COME TO LIGHT