Professor Herb Allen Testifies Before Subcommittee on Energy and Mineral Resources
September 25, 2003

by Diane Kukich

Dr. Herbert E. Allen, Professor in the Department of Civil and Environmental Engineering at the University of Delaware, was invited to testify before the House Resources Committee Subcommittee on Energy and Mineral Resources on September 25, 2003. Allen is Director of UD's Center for the Study of Metals in the Environment and a recognized expert in the fate and effects of metals in water, sediment and soils. Allen's goal in presenting his testimony was to demonstrate that bioavailability--rather than the total volume of a discharged material--is the critical criterion in predicting toxic effects.

Allen explains that, following the 1984 gas leak in Bhopal, India, which killed thousands, legislation was passed requiring companies to inform the public about releases of potential pollutants and toxic substances into the environment. "This legislation, commonly referred to as 'Right to Know,' has served as a wonderful pollution prevention tool," says Allen, "because companies want to avoid any publicity associated with being a major discharger of pollutants. The only problem with it is that volume has been the criterion used to identify major polluters, and we need to look at better ways to predict the actual effects of metals and other pollutants in the environment."

The recent addition of two major categories--mining and power plants--to the types of operations covered by EPA legislation prompted the invitation to Allen to testify. "With mining," he explains, "the quantities of waste rock are enormous, but the effect of the metals in the rock can be minimal. If you extracted the cadmium from a rock the size of a desk and discharged it directly into the environment, it would be highly toxic. But embedded in the rock, it may not be available to harm human, animal, or plant life. The biggest danger to a fish from a huge mining rock wouldn't be from the heavy metals in it but from the impact of it hitting the fish and crushing it."

In making this point in his testimony, Allen said to the subcommittee members, "Mining waste materials often contain metals, such as copper and lead, and metalloids, such as arsenic, that are commonly regarded as having the potential to be toxic to humans and to organisms in the environment. Whether toxicity occurs depends critically on the physical and chemical composition of the waste material and on the chemical conditions in the environment receiving the waste material."

"The total concentration of a contaminant is not predictive of the toxicity observed for either humans or for other animal or plant species," he continued. "Only the bioavailable fraction causes a toxic response. Both the chemical form of a substance and interactions of the contaminant and the organism with other substances affect the bioavailability of the contaminant. In addition there must be exposure of the organism to the contaminant before any toxic response can occur."

He concluded by saying, "Currently EPA is developing a Framework for Assessing Hazards and Risks of Metals and Metal Compounds.... The Agency should be encouraged to apply the best science available as they complete the Framework. This would emphasize the key roles of incorporating exposure and bioavailability in the assessment of risk of metals."