BILLINGS, Mont. (AP) — Federal officials anticipate finishing by late 2014 a risk study to guide the cleanup of an asbestos-contaminated Montana mining town, after a panel of scientists backed draft results that say even a minuscule amount of the substance can lead to lung problems.

The long-awaited document will determine when work can end on the cleanup of asbestos dust from a W.R. Grace & Co. vermiculite mine outside Libby, Mont. Hundreds of people in and around Libby have died from exposure, and many more have been sickened.