Complexity Persists in Using Sunscreens

by Food and Drug Administration (FDA)

You would think that all the questions about sunscreens have been answered by now. You slather it on before you go to the beach. It keeps you from being fried to a crisp. And, if you use enough, it helps prevent your skin from taking on that wrinkled, leathery look of photo-aged skin. Best of all, it protects you from the harmful ultraviolet rays that cause skin cancer.

If that's your perception, you're mostly right, but that view is not complete. While all the basic information remains true — sunscreens do protect skin from sunburn — a scientific debate simmers about the importance of lower-energy ultraviolet light to skin damage and whether current sunscreens provide adequate protection.

Just recently, the Food and Drug Administration delayed until December 2002 the implementation of a so-called final monograph on sunscreens- the kind of rules that FDA publishes for the more than 100,000 over-the-counter (OTC) drug products currently on the market. OTC drug monographs — which cover 80 classes or therapeutic categories of OTC drugs, including sunscreens — are a kind of "recipe book" covering acceptable ingredients, doses, formulations, and labeling. Once a final monograph is implemented, companies can make and market an OTC product without the need for FDA pre-approval. New prescription drugs, on the other hand, require pre-approval before they can go on the market.

In 1997, Congress ordered FDA to issue regulations on the prevention and treatment of sunburn. The agency completed the sunscreen monograph in May 1999 to meet the congressional mandate, and it initially gave the industry until May 2001 to implement it. The new regulation established a list of 16 active ingredients that companies can use in sunscreen products and simplified the labeling so consumers will know how to use these products properly. The monograph also applied to sunscreen-containing cosmetics.

But questions about the harmfulness of a certain type of ultraviolet light and how to best label sunscreens led FDA to delay these regulations until further studies could be conducted.

Sunburns and Suntans

Sunburn, which is caused by a type of ultraviolet (UV) light known as UVB, has served as a surrogate for more serious skin disorders, such as melanoma and basal and squamous cell carcinoma, three forms of skin cancer. Basically, the thinking was if you prevent sunburn, you'd prevent skin cancer.

In recent years, however, scientists have come to appreciate that a different form of ultraviolet light, called UVA, may be just as, or even more, important in causing some skin disorders. Although experts still believe that UVB is responsible for much of the skin damage caused by sunlight — especially sunburn — UVA may be an important factor in other types of sun damage, including photoaging and the development of skin cancers. Most sunscreens do a good job blocking UVB but fewer filter out most of the UVA.

"Both laboratory and epidemiological studies indicate that sunscreens may not block the initiation or promotion of melanoma formation," says Ronald D. Ley, Ph.D., at the University of New Mexico School of Medicine's Steve Schiff Center for Skin Cancer in Albuquerque, N.M. Studies using a fish model of melanoma induction "suggest that the action spectrum [the defined wavelength of ultraviolet light that damages skin] for erythema induction is different than the action spectrum for the induction of melanoma." Erythema means red skin, that is, sunburn.

"There are a lot of data on both sides of the question about the tanning link to melanoma," says John Lipnicki of FDA's Center for Drug Evaluation and Research (CDER).

Now, with extra time before the monograph will be implemented, FDA and the scientific community have gone back to wrestling with the thorny questions that were not resolved in the initial document. Researchers will further study active ingredients, and test methods to measure how well products block UVA's effect on the skin. The agency will also work to make the labeling clearer.

Risks and Reality

These questions transcend academic curiosity. The death rate from melanoma in the United States has been going up about 4 percent a year since 1973, according to the Centers for Disease Control and Prevention in Atlanta. Although melanoma represents only about 47,000 of the nearly 1.8 million cases of skin cancer diagnosed each year, according to the American Cancer Society, it will cause 79 percent of skin cancer deaths. While cancer treatments continue to improve, melanoma recovery rates remain disappointing. Prevention is the better solution.

As prevention, however, sunscreens alone appear to be imperfect. In the first study to test the protective effect of sunscreens on people — not just the hairless mice or other models used in laboratory studies — researchers at the Queensland Institute for Medical Research in Brisbane, Australia, reported in September 1999 that sunscreen use reduces the risk of developing squamous cell carcinoma by 40 percent. But using sunscreen did not reduce the risk of developing melanoma or basal cell carcinoma. The Australian study followed 1,383 adults for five years.

FDA believes sunscreens are an important part of a person's total sun protection strategy, but that sunscreen use alone will not prevent all of the possible harmful effects due to sun exposure, according to agency statements. Borrowing the "Slip, Slop, Slap" slogan from an Australian skin cancer prevention campaign, the American Cancer Society recommends that anyone out in the sun slip on a shirt, slop on sunscreen and slap on a hat.

The education campaign's benefits in Australia have been promising, says Robin Marks, M.B., of the University of Melbourne. "Suntans are out of fashion, especially deep tans. We can measure sunburn rates, and they have gone down." Most importantly, the epidemiological studies show the rates of skin cancer, including melanoma, are going down in the younger groups, says Marks, but not in the older groups whose skin already has been damaged by prior exposure to the sun.

As FDA ponders adjustments to the sunscreen monograph before its implementation, the agency finds itself in the familiar position of needing to make regulatory decisions about important public health issues in the face of scientific uncertainty.

About the Author

www.fda.gov
FDA is A United States government body that oversees medical devices, including contact lenses, intraocular lenses, excimer lasers and eyedrops. In the US, these products must be approved by the FDA before they can be marketed.