UNDATED (KDAL) - A long study of Iron Range mine workers will be released by the University of Minnesota in April. The study began because of much higher rate of a rare form of lung cancer showing up in mine workers than in the general population. At least 82 taconite workers have died from mesothelioma in recent years. The cancer often doesn't appear for 30 to 40 years after the first exposure to asbestos fibers. The UM research focused on 50 thousand people born since 1920 who worked in the production of taconite.