Erionite in North Dakota roads may increase risk of mesothelioma

As school buses drive down the gravel roads in Dunn County, North Dakota, they stir up more than dirt. The clouds of dust left in their wake contain such high levels of the mineral erionite that those who breathe in the air every day are at an increased risk of developing mesothelioma, a type of cancer of the membranes around the lungs, new research shows. Erionite is a natural mineral fiber that shares similar physical similarities with asbestos. When it's disturbed by human activity, fibers can become airborne and lodge themselves in people's lungs. Over time, the embedded fibers can make cells of the lung grow abnormally, leading to mesothelioma, a form of lung cancer most often associated with the related mineral asbestos.

Michele Carbone, M.D., Ph.D., director of the University of Hawaii Cancer Center in Honolulu, has previously linked erionite exposure in some Turkish villages to unusually high rates of mesothelioma. Recently, he and colleagues turned their attention to potential erionite exposure in the U.S., where at least 12 states have erionite-containing rock deposits. His research team-which includes scientists from the National Institute of Environmental Health Sciences, Environmental Protection Agency, New York University, University of Chicago, University of Iowa, and University of Hacettepe-focused their efforts on Dunn County, North Dakota, when they learned that rocks containing erionite have been used to produce gravel for the past 30 years. More than 300 miles of roads are now paved with the gravel. The new study, reported in the July 25, 2011 issue of Proceedings of the National Academy of Sciences (PNAS) is the first to look at the potential hazards associated with erionite exposure in the U.S.

The scientists compared the erionite in North Dakota to erionite from the Turkish villages with high mesothelioma rates. They measured airborne concentrations of the mineral in various settings, studied its chemical composition, and analyzed its biological activity. When mice were injected with the erionite from Dunn County, their lungs showed signs of inflammation and abnormal cell growth, precursors to mesothelioma. Under the microscope, the fiber size of the erionite from North Dakota was similar to that of the Turkish erionite. Overall, the researchers found no chemical differences between the North Dakota erionite and samples of the cancer-causing mineral from Turkey. The airborne levels of erionite in North Dakota were comparable to levels found in Turkish villages with 6-8 percent mortality rates from mesothelioma, the researchers reported.

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