Since 1987, the Environmental Protection Agency has required all manufacturing companies that emit pollutants to submit annual reports totaling the amount and type of emissions. In 1997, the types of industries required to report were expanded to include mining companies and power plants.

Mining companies like Kennecott are screaming foul because the materials being listed as toxic are usually nothing more than natural rocks being pulled out of the mountainside and left behind because they did not contain enough ore to be processed.

"The TRI is the most misleading inventory I know of," said Kennecott spokesman Louis Cononelos. "You move one rock and it becomes toxic. It makes no sense." Theoretically, the Toxic Release Inventory allows citizens to know the types of toxic substances released by companies in their neighborhoods.

In reality, "Knowing the pounds of exotic chemicals is not going to help people (assess the risks)," said Neil Taylor, an environmental scientist with the Utah Department of Environmental Quality. "There are a lot of questions about what the numbers really mean."

A more important question, he said, is how the companies manage the toxic chemicals and whether they are allowed to escape the confines of the business properties and contaminate neighborhoods. That question is not addressed in the TRI, nor is information provided about the dangers of particular chemicals.

"Gross poundage doesn't mean anything in terms of managing risk," Taylor said.

Still, for all its flaws, the TRI is the only tool whereby the public can readily determine what kinds of toxins are produced by industry in their neighborhoods. But it's fairly complex and esoteric, and without advanced degrees in chemistry and epidemiology, the report probably doesn't mean much to an individual trying to assess environmental risks.

More than anything, the TRI has become a tool for state environmental regulators and health officials who can now compare and contrast pollution data with health dangers. For example, epidemiologists looking at clusters of cancers or rare diseases now have a "one-stop shop" for pollution data from nearby businesses.

Taylor said environmental regulators often knew that chemicals were being released, but until the TRI they didn't know exactly how much, nor specific types. In some cases, regulators did not have an inkling of certain releases until the TRI.

"More than anything, the TRI has changed company policy," Taylor said. "They are uncomfortable reporting the chemicals, they don't want to be on the list."

Still, Taylor cautions against putting too much stock in the TRI. For starters, there are smokestack-sized loopholes in the TRI reporting requirements.