Lights, chemicals, action at new lab for phototoxicology.

In the delta of southeastern Arkansas, at the National Center for Toxicological Research in Jefferson, two large laboratory rooms are bright with sunlight-not the kind that streams in through windows, but simulated solar energy from tiny lamps using an electromagnetic radiation source that closely mimics the spectrum of sunlight. There, in the heart of the new Phototoxicology Research and Testing Laboratory, hairless mice are coated with creams similar to ones used daily by millions of people in search of a more "youth-ful" appearance. The question that scientists want to answer is whether the natural acids now found in almost every skin care cream on the market may actually promote skin cancer. Researchers are concerned that these acids, known as alpha-and beta-hydroxy acids, might peel away layers of the skin to the point where sunlight can damage DNA in cells at the skin's deepest od corneum) and epider-mal tissues. According W i U to the FDA, two consequences of using creams containing these acids are increased proliferation ___ ~ of epidermal epithelial cells and deeper penetration of electromagnetic radiation into the skin, both of which raise the possibility of an increased risk of skin can cer with continued use. Says Paul C. Howard, director of the phototoxicology laboratory, "Vanity may have a price." "It became apparent after surveying the literature and consulting with colleagues that in order to understand the carcinogenic potential of the alpha-and beta-hydroxy acids, studies would have to be designed to determine the effects of these acids on ultraviolet (UV) light-indLuced skin cancer in mice," says Howard. The FDA and the NIEHS joined together to fund a facility that would allow the simultaneous exposure of the large numbers of mice required for such studies, as wx ll as future studies on compounds that mayr affect skin cancer rates. The key features of the new facilitv are two miniature suns-six-inch xenon arc lamps that operate at 6,500 watts. The. vlisible and _m UV radiation emitted from each lamp, when filtered through glass designed to simulate the earth's atmosphere, closely mimics the spectrum of solar light. Researchers at the laboratory canl expose about 5,000 mice a day to the simulated solar light. Although, says Hoxxvard, SUI1-light can be simulated on a small scale (dozens of mice per day) with cqulipmllellt found in universits laboratories, car-cino-genicity studies can be laige and are verv difficult to do. "Thie numLibers of animllals rcquircd …