The state attorneys general in Minnesota and Wisconsin are joining environmental groups to stop Northshore Mining Co. efforts in federal court to lower the standard for fibers in the air near the company's Silver Bay taconite plant. The states and environmental groups vehemently oppose the company's motion to drop the standard, set in 1974, for asbestos-like fibers in the air near the taconite plant along the shore of Lake Superior. Fibers found in taconite dust in the eastern parts of the Iron Range, may cause health problems, particularly lung ailments like mesothelioma. The current, court-ordered standard requires Northshore to keep fibers in the air near Silver Bay at or below the average level of fibers in St. Paul air. The company claims that the comparison between Silver Bay and St. Paul air is outdated, and that the fibers pose no human health risk and dropping the standard won't result in increased fibers in Silver Bay, but would end an unfair comparison to fluctuating St. Paul fiber levels. Wisconsin Attorney General J.B. Van Hollen noted that recent reports from the Minnesota Department of Health show unusually high levels of mesothelioma in the region. The disease is caused only by exposure to asbestos fibers.