Apr. 20--NASHVILLE -- Politics, pollution, science and a lawsuit are all entangled in a complex and increasingly heated legislative debate over how much of a naturally occurring mineral can be freed to flow into Tennessee streams.

Proponents such as the sponsor, House Conservation and Environment Committee Chairman Joe McCord, say the bill simply applies the latest in scientific research to state water quality standards.

Critics such as Rep. Mike McDonald, who has been mentioned as a potential appointee to the TVA Board of Directors, say the move is an unprecedented attempt to let the coal industry, through the Legislature, dictate to the Department of Environment and Conservation professionals how much pollution it can produce.

The mineral, selenium, is essential to human health in small amounts. Chuck Laine, lobbyist for the Tennessee Mining Association, says he takes it as a supplement and that "it makes me feel better."

But it is toxic to humans in high amounts and can kill aquatic life in smaller amounts that would be harmless to people.

The bill -- SB1331 -- is pushed by the coal industry and staunchly opposed by environmentalists. It would relax state standards for release of selenium -- typically through coal-mining operations -- into Tennessee waters.

Selenium also is found in the coal ash released into the Emory River at TVA's Kingston Fossil Plant in December, though those involved in the legislative debate say the bill would have no direct impact on that situation.

The Sierra Club, Save Our Cumberland Mountains and the Tennessee Clean Water Network filed a U.S. District Court lawsuit last October against Knoxville-based National Coal Corp. contending the company has been releasing selenium into streams around its Zeb Mountain operations in Campbell and Scott counties in amounts that exceed the current state standard.

Mary Mastin, Sierra Club attorney, said passage of the bill would "muddy the waters" in the lawsuit, though not directly impact the legal action because it is based on releases that have already occurred. Laine said the bill is "irrelevant" to the lawsuit.

The bill would adopt as Tennessee's selenium standard the levels proposed by the Environmental Protection Agency in 2004.

The current state standard dates to 1987, a time when Laine says states were not even measuring selenium when checking for pollution.

"We hadn't been measuring selenium for 20 years in Tennessee, and now we are," said Laine.