Tracing the environmental effects of metals

Most people are aware that high concentrations of "heavy" metals in soil and water can be harmful to land and marine animals and plants, upsetting delicate ecological balances and contaminating food sources.

But, how much is too much? What level of zinc or mercury will affect the reproductive rates of fish or, even worse, cause the death of an entire colony of marine organisms? How much cadmium, chromium or copper does it take to induce illness in people who eat affected species?

A new research center led by the University is aimed at developing an understanding of the processes affecting the fate of metals in aquatic and terrestrial ecosystems and the biological effects of metals in these systems–an understanding that, researchers say, will help to answer these questions and dozens more. Herbert Allen, professor of ?civil and environmental engineering, has been selected as the first director of the Center for Metals in the Environment, a consortium of researchers from eight U.S. and Canadian educational institutions. In addition to UD, the consortium members are the Colorado School of Mines, Manhattan College, McMaster and Oklahoma State universities and the universities of Alaska, Missouri at Rolla and Wyoming.

"These universities were selected for their complementary research capabilities," Allen said. "Each of them has several researchers working on the chemical, toxicological and ecological aspects of metals in the environment. Both government and industry respect the scientific research they conduct, and their scientific expertise is sought to provide insight to understanding of metals-related issues."

Allen points out that the past few years have witnessed increased attention focused on issues related to trace metals in the environment, but decisions about how to mitigate the effects of these potential pollutants need to be based on sound scientific principles.

"Appropriate criteria are needed if we're going to protect the desired resources," he said. "If the criteria are set at values that are too high, then they don't do enough to protect. On the other hand, if they're set too low, then the cost of compliance is excessive– sometimes resulting in the regulations becoming unenforceable and resulting in no protection at all. This dilemma is usually the result of a lack of understanding of the mechanisms and routes of exposure."

One problem is that much of the existing methodology for hazard identification and risk assessment is based on experience with organic pollutants, such as DDT and PCBs. However, the significant differences between organic compounds and metals are not accounted for in these methods.

"For example," Allen said, "metals don't degrade the way organic materials do. While the risk posed by organic chemicals is evaluated by examining their degradation rates, a model is needed for the behavior of metals and metal compounds that can be used as a tool in assessing the hazard they pose." Another difference is that the toxicity of metals depends on the environmental chemistry of the actual environment to a far greater extent than the toxicity of organic chemicals does–a factor that must be incorporated into risk assessment.

The Center for Metals in the Environment was formed as an outgrowth of a consortium funded through a cooperative agreement with the Environmental Protection Agency's Office of Water from 1994 until the end of the 2000 fiscal year. UD is currently seeking EPA funding for general support of the center, which was established in 2000 by congressional order. Once the funding is in place, three integrated research projects will be initiated. Each project will involve investigators from multiple institutions and will address specific topics within the three broad areas of aquatic toxicity, terrestrial toxicity and risk assessment.

The center's activities will comprise education, outreach and technology transfer, as well as research. "The consortium was able to play an important role in the development of new tools for risk assessment of metals in the environment," Allen said. "These tools were readily incorporated into EPA programs because of the close liaison that we maintained with their program offices. If the center is to be a national and international resource for regulators, industry, researchers and the public, our 'technology transfer' efforts will have to go beyond publication of our research in peer-reviewed journals, so that we can eliminate–or at least reduce–the long time delay that usually exists between conducting and publishing research and its incorporation into regulatory and management programs."

Eventually, if funding permits, an Office of Trace Metal Information will be formed within the center to work with center researchers and staff.