The Effects of Common Substances on Sun-Exposed Skin

by Food and Drug Administration (FDA)

A beauty-conscious public clamors for cosmetics formulated to give a more youthful look. Yet some ignore the warnings of premature aging and worse to pursue a love affair with the sun. Others prefer the needle-and-ink approach when it comes to skin enhancement. The once-taboo practice of tattooing in its various forms has moved out of seedy parlors frequented by bikers and sailors and onto the backs, shoulders, ankles, and arms of mainstream America.

These obsessions with appearance have one thing in common: skin — the largest organ of the human body.

Sensitive enough to feel a gentle breeze, yet tough enough to resist all kinds of environmental assaults, skin creates the first line of defense against possible invasion by bacteria and other germs. Skin also secretes lubricating fluids that serve as a barrier to toxic substances.

Skin can be a virtual open book to a person's state of health. Very red skin, for example, may mean high blood pressure, while sagging, leathery skin is the hallmark of a long-time smoker or sun-worshipper.

Experts already know that exposure to ultraviolet radiation (UVR), either from sunlight or by artificial sources, contributes to the risk of developing skin cancer. Now, because of the public's increasing exposure to UVR through outdoor activities and more frequent use of artificial sources, the Food and Drug Administration's National Center for Toxicological Research (NCTR) in Jefferson, Ark., is studying whether the combination of sun and the ingredients found in cosmetics or the chemicals used in tattoo inks can be linked to toxic effects or cancer.

The Skin You're In

Sunlight reduces the skin's elasticity, leading to premature aging in the form of early wrinkles. Since sun damage may not be immediately visible, many people don't realize the dangers of tanning. In fact, any tan is a sign of adaptation of the skin to potentially damaging UVR. Tanning occurs when the skin produces additional coloring (pigment) to protect itself against sunburn. The most serious consequence of overexposure to the sun is skin cancer, a delayed effect that usually doesn't show up for many years.

Health and Human Services Secretary Tommy G. Thompson strongly warns young people to take simple preventive steps now to help avoid skin cancer later. "Even a few serious sunburns," he says, "can increase a person's risk for skin cancer."

Sunburn is associated with the shorter wavelengths of UVR, known as ultraviolet B (UVB). The longer wavelengths, known as ultraviolet A (UVA), however, can penetrate the skin and damage connective tissue at deeper levels, even if the skin's surface feels cool. It is important to limit exposure to both UVA and UVB.

Sunlamps used for tanning produce UVR. FDA policies require sunlamp product manufacturers to develop an exposure schedule and establish a maximum recommended exposure time based on the UVR emission characteristics of their products. The agency also warns that, while some tanning operators may claim that UVA sunlamps are safer than both the sun and UVB lamps, this has not been definitely shown. In fact, exposure to UVR from sunlamps adds to the total amount of UVR people get from the sun during their lifetimes, potentially increasing their risk of cancer.

Physicians and scientists are especially concerned that cases of skin cancer — the most common type of cancer in the United States, according to the National Cancer Institute — will continue to increase as people now in their teens and twenties reach middle age. The incidence of skin cancer is increasing each year, and melanoma, the most serious form, is increasing by 3 percent annually. In fact, statistics indicate that 1 out of 7 people in the United States will develop some form of skin cancer during their lifetimes.

Many dermatologists believe that there may be a link between childhood sunburns and melanoma later in life. Linda L. Lutz, M.D., assistant professor of dermatology at the University of Maryland in Baltimore, says, "Most of the sun damage we receive is before age 20. It's the cumulative effect of sun exposure that causes problems."

While the link between sun exposure and skin cancer has been established, FDA scientists are looking into the effects of the thousands of chemicals that go into commonly used cosmetics and what effects, if any, the chemicals may have on the skin when combined with sunlight.

Testing the Safety of Chemicals

Today, more than 80,000 chemicals are registered for use in the United States in everyday items such as foods, drugs, and personal care products, according to the Department of Health and Human Services' National Toxicology Program (NTP). An estimated 2,000 new ones are introduced each year. The effects of many of these chemicals on health are unknown. For scientists in general and regulatory agencies in particular, the tasks of researching and regulating these chemicals are daunting. Since the FDA is responsible for protecting the public health in regard to chemicals included in foods, drugs, and cosmetics, research at NCTR contributes to the FDA's ability to regulate and ensure the safe use of products containing these ingredients. NCTR studies investigate the toxicity of these chemicals, contributing to a database used by the FDA to make regulatory decisions.

The NTP is based at the National Institute of Environmental Health Sciences (NIEHS), one of the National Institutes of Health. It was established in 1978 to set priorities and coordinate the testing of chemicals that the public may be exposed to. Advised by several government agencies, the NTP manages information on potentially hazardous chemicals added to a variety of industrial and consumer products, as well as those occurring in food naturally or as unintentional contaminants.

The FDA and the NIEHS established an interagency agreement in 1992 to cooperate on toxicological studies. The agencies recognized the need for toxicological testing on chemicals in the presence of sunlight (phototoxicology). The result, in 1998, was the construction of a new laboratory, designated as the NTP's Center for Phototoxicology (NCP).

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.