As skin cancer rates rise (a recent study found the incidence of basal cell and squamous cell cancer has tripled in women under age 40), chemists are scrambling to find new ways to help subdue this disease. Some of this cutting-edge research - from better understanding of the skin pigments to lotions that offer the hope of repairing skin damage after a long day in the sun - will be discussed during a two-day symposium, "Frontiers in Photobiology," Aug. 28-29, at the 230th national meeting of the American Chemical Society, the world's largest scientific society. The symposium begins at 8:20 a.m. Sunday at the Washington Convention Center, Room 143C. Selected highlights include:

Hair color and the risk of skin cancer - Although anyone can get skin cancer, the risk is greatest for people who have fair skin that freckles easily - often those with red or blond hair and blue or light-colored eyes. In the first study of its type, John Simon and others at Duke University in Durham, N.C., have found that red pigment - found in people who have blond or red hair - is more apt than black pigment to produce damaging compounds when exposed to the sun. These compounds, called free radicals, can initiate a chain reaction in skin cells that lead to the development of cancer. (PHYS 19, Sunday, Aug. 28, 9:40 a.m.)

What's a possum got that you don't? - Life in the sun is a lot more fun for algae and possums because they have built-in gene repair kits, which protect them from cancer. An enzyme, called photolyase, repairs DNA damage caused by ultraviolet light in many organisms, but not in humans. Olaf Wiest and other researchers at the University of Notre Dame studied how the natural enzyme works and have made a molecule that apparently also repairs DNA in laboratory experiments. This basic research finding could be a step towards developing a new way to prevent skin cancer in people. (PHYS 46, Sunday, Aug. 28, 2:00 p.m.)

Morning-after skin cell repair - Even the best sun screens can't prevent all skin damage. But a new topical lotion, developed by scientists at AGI Dermatics in Freeport, N.Y., is poised to become the first skin-repair drug. The lotion contains a natural protein called T4 endonuclease, which in laboratory test tubes has been shown to increase repair of human cells. Oil sacs in the lotion allow the protein to penetrate into skin cells. Once inside a cell's nucleus, the protein removes damaged areas of DNA and starts a repair process that the body completes. The lotion and the protein enter cells within an hour of application and produce measurable results within six hours, says principal investigator Daniel Yarosh, Ph.D. Currently in clinical trials, the drug has been shown to protect against UV-induced immune suppression in the skin and reduce the incidence of skin cancer in people who used it daily for one year, Dr. Yarosh says. These people, who had a rare genetic disease called xeroderma pigmentosum, which makes them highly susceptible to skin cancer, had, on average, 30 percent fewer basal cell carcinomas and 68 percent fewer precancerous lesions than those who used a placebo. Dr. Yarosh will present new results on the importance of DNA repair in protecting the human immune system so it can fight off skin cancer. Because the drug appears to initiate skin repair even when applied after too much sun, some refer to it as "morning after" sun protection. (PHYS 108, Monday, Aug. 29, 1:30 p.m.)

The American Chemical Society is a nonprofit organization, chartered by the U.S.

Congress, with a multidisciplinary membership of more than 158,000 chemists and chemical engineers. It publishes numerous scientific journals and databases, convenes major research conferences and provides educational, science policy and career programs in chemistry. Its main offices are in Washington, D.C., and Columbus, Ohio.