Federal and state laws protect you from having to work in dangerous or hazardous conditions. The main federal law covering threats to workplace safety is the Occupational Safety and Health Act of 1970 (the "OSH Act" -- 29 U.S.C. § 651 and following). The OSH Act gives you a number of rights if you think that some aspect of your workplace or working conditions is unsafe. See Nolo's article Dealing With Workplace Health and Safety Issues for more information.
Most state laws track the federal law fairly closely. To find out about workplace safety laws in your state, contact your state labor department.