Race May Not Predict
UV-Related Skin Damage

WASHINGTON (Reuters Health) - People with darker skin may be less susceptible to the sun's damaging rays, but researchers are discovering that race may not be the main predictor of who will most likely be permanently damaged by ultraviolet radiation.

In two studies presented here Friday at the Food and Drug Administration's annual Science Forum, FDA and National Cancer Institute (NCI) researchers showed that skin type may be a better determinant of cancer risk. Dermatologists classify skin type on a six-point system, according to how easily someone burns and how much they tan. A person classified as ``I'' burns easily and never tans, a ``III'' burns slightly and tans light brown, and a ``VI'' never burns and tans to a dark color.

The two government studies are examining the same group of 110 patients, using different lab methods, and seeking slightly different answers. Results so far show that whites, Asians, Native Americans and Pacific Islanders tend to have all the skin types--from I to VI--no matter the base skin color. Lighter skinned races showed a wide variety of sensitivity to UV radiation, from totally sensitive to ``resistant,'' researchers reported.

African Americans tended to have similar dark skin types, and to be more resistant to UV's damaging properties.

Even so, researchers found that dark skin does not guarantee protection. After exposing 52 trial participants to measured doses of UV radiation, the damage to each person's DNA was significant, no matter what race or skin type.

Damage was greatest immediately after exposure, and they found that production of melanin--the pigment in skin--was suppressed. When exposed to the sun, it was thought that the skin tends to produce more melanin, which helps protect deeper skin levels from damage.

African Americans and darker-skinned races have more melanin at baseline, which is why they have been presumed to have greater protection.

But the researchers found that melanin production stopped after UV exposure, and that the result was the same in all the races after exposure. Some individuals had greater suppression, leading to longer DNA repair times.

In most cases, no matter skin type or color, DNA eventually repaired itself, usually within a week. It has already been known that DNA is damaged from UV exposure, and that cumulative insults likely lead to cancer.

When the study is complete, the researchers hope to show who is most at risk. They hope to show that the amount of melanin content and production in different skin types is related to how fast--and how well--DNA is repaired. This information will help physicians predict which skin types or races are most vulnerable to skin cancers, the researchers said.

The study results will also be used by the FDA to set UV exposure standards.

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