Last year, the Bay states agreed to substantial reductions in the amount of toxic chemicals entering the environment from manufacturers and federal facilities. Whether those reductions ever become a reality, though, now hinges on something the states have no direct control over: Congress and the courts.

The reason is that almost all the quantifiable toxics reductions called for in the "Basinwide Toxics Reduction and Prevention Strategy" are tied to the EPA's Toxics Release Inventory. Certain industries are required to make annual reports of chemicals on the TRI list under the 1986 Emergency Planning and Community Right-to-Know Act.

Regulatory reform legislation in the Senate would require the EPA to remove all chemicals from the list for which there is insufficient evidence to show acute toxicity beyond the facility boundaries.

Opponents of the bill say that would ignore potential environmental impacts posed by the chemicals, or the long-term chronic effects of continued exposure to low levels of chemicals.

The bill would also require the EPA to prove that a chemical on the TRI list could cause harm before requiring companies to report releases. Because the TRI list is used for information gathering, not regulatory actions, the agency does not currently have to prove the health impacts of listed chemicals.

In addition, the Chemical Manufacturers Association has filed a suit against the EPA seeking to force the agency to halt collecting data on the 286 chemicals it added to the list beginning this year. The House approved a "rider" to the EPA's 1996 appropriation that would also prevent the agency from gather ing TRI data on those additional chemicals.

Critics charge that TRI stigmatizes all chemicals on the list regardless of their toxicity, some can be harmful in small doses while others may require huge exposures before posing a significant threat to health or the environment.

John Shanahan, environmental policy analyst with The Heritage Foundation, a conservative think-tank, claimed in a USA Today opinion piece this year that TRI reporting costs industry $1 billion a year for such things as compliance costs and taxes levied in 13 states on TRI chemicals. And, he said, chemicals on the list lose market share compared with non-listed chemicals, regardless of toxicity.

But TRI proponents have labeled efforts to roll back TRI reporting as "right-to-know-less" legislation. They said the data has provided the public with knowledge of pollution sources in their neighborhoods and, in many cases, has prompted companies to find ways to reduce emissions that save money. Dow Chemical, for example, has estimated saving between $10 million and $20 million in each of the past two years because of TRI-inspired efficiencies.

This summer, President Clinton also weighed into the debate. In an Aug. 8 speech that used Baltimore Harbor as a backdrop, he threatened to veto efforts to weaken TRI and announced an executive order requiring companies doing business with the federal government to comply with pollution disclosure rules. He also ordered the EPA to speed up expansion of the TRI to include currently exempt industries and more data on the chemicals industry uses.