The majority of flint disease cases occur among workers in various manufacturing industries that create stone dust. According to a study conducted between 1993 and 1997, such workers accounted for 67.4 percent of cases. Manufacturing as an industry saw 85.8 percent of cases. The study, which examined cases from Michigan, New Jersey, and Ohio, found 576 cases in those three states. From 1990 to 1997, the mortality rate for flint disease was 1.21 per million for the entire United States. Vermont, Pennsylvania, West Virginia, Colorado, New Mexico, and Utah saw higher mortality rates (greater than 3.0 per million).