GSA Annual Meeting in Denver, Colorado, USA - 2016

Paper No. 217-6
Presentation Time: 3:05 PM


BUCK, Brenda J., Geoscience, Univ of Nevada, Las Vegas, Box 4010 Lilly Fong Hall, 4505 Maryland Parkway, Las Vegas, NV 89154, METCALF, Rodney V., Dept. of Geoscience, Univ of Nevada - Las Vegas, Las Vegas, NV 89154-4010, BERRY, David, Environmental Protection Agency, Region 8, 1595 Wynkoop Street, Denver, CO 80202, MCLAURIN, Brett T., Department of Environmental, Geographical and Geological Sciences, Bloomsburg University of Pennsylvania, 400 E. 2nd St., Bloomsburg, PA 17815, KENT, Douglas, TechLaw, ESAT Region 8, 16194 W 45th Drive, Golden, CO 80403, GOOSSENS, Dirk, Division of Geography, KU Leuven Department of Earth and Environmental Sciences, Geo-Institute, Celestijnenlaan 200E, Leuven, 3001, Belgium and JANUCH, Jed, Environmental Protection Agency, Region 10, Laboratory 7411 Beach Drive East, Port Orchard, WA 98366,

Naturally occurring amphibole asbestos has been found in rock, soil, and dust in both urban and rural areas of southern Nevada and northwestern Arizona. In southern Nevada, although rates of malignant mesothelioma are similar to the mean USA rate, there are unusually high percentages of malignant mesothelioma cases in young individuals and women, compared to the USA as a whole. These data are strongly suggestive for environmentally-caused asbestos-related disease. The primary exposure route is through inhalation. The asbestos occurs in areas frequently disturbed by activities such as off-road driving, hiking, horseback riding, and construction, which create dust and cause fibers to become airborne. Rock, soil, dust and clothing were analyzed using scanning electron microscope and energy dispersive spectroscopy; additional rock samples were analyzed using wavelength dispersive electron probe microanalysis; additional soil samples were analyzed using polarizing light microscopy and transmission electron microscopy using the Fluidized Bed Asbestos Segregator preparation method. The asbestos is sourced from plutonic rocks with fibrous Ca-amphiboles occurring primarily in Nevada (actinolite, magnesiohornblende), and Na-amphiboles occurring primarily in northwestern Arizona (winchite, magnesioriebeckite, richterite). Wind erosion, transport, and deposition have resulted in soils containing mixed Ca- and Na-amphiboles. Erionite/offretite, which has not previously been reported in this area, was a common soil component found in 5 of 6 soil samples. The source of the erionite/offretite is currently unknown. Additionally, winds have transported the amphibole and erionite/offretite particles into the Nellis Dunes Recreation Area, located 35 km north of Boulder City that otherwise would not be geologically predicted to contain fibrous amphiboles. In Boulder City, wind directions are primarily bimodal N-NE and S-SW with the strongest winds in the spring coming from the S-SW. The arid climate in this part of the Mojave Desert greatly increases the potential for wind erosion and human exposures. These results suggest that the entire Las Vegas Basin has, at times, received mineral fibers through wind transport. The Las Vegas metropolitan area currently has a population of over 2 million people.