After more than two years of debate over how to best clean up toxic asbestos in and around Libby, Mont., the U.S. EPA formally agreed yesterday to designate the area as a Superfund site. The U.S. EPA has been working to clean the area since late 1999, but Montana Gov. Judy Martz (R) initially opposed Superfund listing for the site. After months of pressure and 90 percent public support for the listing, the governor changed her mind — and even went so far as to opt to use the state’s one and only so-called “silver bullet,” an option to fast-track the cleanup. The fast-tracking places the site among the nation’s 100 most important cleanups, thereby securing greater spending and more prompt attention. Libby and surrounding areas were contaminated by asbestos from a vermiculate mine owned by the multinational company W.R. Grace. The mine, which closed in 1990, has been linked to scores of illnesses and almost 200 deaths.