A revised proposal looks to protect existing frac sand mines in Wisconsin from new regulations.
The measure would prevent local governments from imposing any new air or water ordinances on those operations.
A joint committee held a hearing on the bill Monday.
Democrats argue it would prohibit local governments from doing anything if studies show a particular mine is causing health problems.
Republicans say there is no proof that sand mines cause lung disease.
"This bill freezes in place the public health safety and welfare protections for a community as they relate to existing sand mines," said State Senator Kathleen Vinehout, a democrat from Alma.
"We have our DNR, we have our EPA, if there's new information that comes out, those agencies are going to take care of those things," said Republican State Senator Joan Ballweg from Markesan.
The bill was introduced three days ago and appears to be on the fast track for a full vote.