Messenger - Vol. 3, No. 3, Page 10 Spring 1994 On Research Researcher tracks metals on the move Buried deep beneath the Earth's surface, metals pose no threat to human health or the environment. A common caveat holds that when such metals are set free, however, they can wreak havoc in water and soil. That's not necessarily true, says Herbert E. Allen, professor of civil engineering. Allen and his colleagues study the "speciation," or transformation, of metals, as they move through soil, water and sediment. To prevent environmental damage, regulatory authorities set maximum limits for lead, silver, copper and other metals in the environment. For example, silver used in photography, printing, dentistry and radiology is thought to be harmful to aquatic organisms-even at levels of less than 1 microgram per liter of water. Trace amounts of copper can also cause problems, and lead poisoning from paints, water pipes and gasolines has been well-documented in humans. Yet, according to Allen, restrictions on metals in water are often based on "erroneous data." Current water-quality criteria set by federal and state officials reflect toxicity tests performed on aquatic organisms in a laboratory setting, he explains. Yet, metals may be far less toxic in natural waters, where they can be imprisoned by particles that help prevent biological damage. "While it is absolutely essential to protect our environment," Allen says, under the existing regulatory system, taxpayers shell out millions of dollars to protect aquatic life that isn't in any danger. "With limited funds available to clean up so many environmental problems, it's also important to spend money wisely," Allen says. In his view, more cost-effective regulations would be based on an understanding of the chemical processes that transform metals as they move from place to place. "The total amount of metal in water isn't all that important," says Allen. "We should be more concerned about the specific chemical forms of metals present in water-the amount of bioavailable metals in water-and the chemical changes those metals undergo." -Ginger Pinholster