A51U-05
Naturally Occurring Asbestos in the Southern Nevada Region: Potential for Human Exposure
Friday, 18 December 2015: 09:00
3012 (Moscone West)
Brenda J Buck1, Rodney V Metcalf1, David Berry2, Brett McLaurin3, Douglas Kent4, Jed Januch5 and Dirk Goossens6, (1)University of Nevada Las Vegas, Las Vegas, NV, United States, (2)Environmental Protection Agency, Region 8, 1595 Wynkoop Street, Denver, CO, United States, (3)Bloomsburg University, Department of Environmental, Geographical and Geological Sciences, Bloomsburg, PA, United States, (4)TechLaw, ESAT Region 8, Golden, CO, United States, (5)EPA Region 10, Laboratory 7411 Beach Drive East, Port Orchard, WA, United States, (6)Division of Geography, KU Leuven, Department of Earth and Environmental Sciences, Geo-Institute,, Leuven, Belgium
Abstract:
Naturally occurring fibrous actinolite, winchite, magnesioriebeckite, richterite, magnesiohornblende, and erionite have been found in rock, soil, and dust in southern Nevada and northwestern Arizona. The areas containing naturally occurring asbestos (NOA) include urban areas (e.g. Boulder City) and rural areas where people routinely enjoy outdoor activities including horseback riding, running, hiking, bicycling, and off-road-vehicle (ORV) recreation. A recent study showing mesothelioma in young people and women suggests some form of environmental exposure. Rock, soil, dust and clothing were analyzed using scanning electron microscope (SEM) and energy dispersive spectroscopy (EDS); additional rock samples were analyzed using wavelength dispersive electron probe microanalysis (EPMA); additional soil samples were analyzed using PLM (polarizing light microscopy) and TEM (transmission electron microscopy) using the Fluidized Bed Asbestos Segregator preparation method. Winds have transported and mixed the Ca-amphiboles, which are primarily from Nevada, with the Na-amphiboles that are primarily from northwestern Arizona. Erionite, which has not previously been reported in this area, was a common soil component found in 5 of 6 samples. The erionite source has not yet been determined. Winds have transported the amphibole and erionite particles into the Nellis Dunes Recreation Area – an ORV 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 these particles through wind transport. Because the most likely human exposure pathway is through inhalation of dust, the Las Vegas metropolitan area, with over 1.9 million people, may be subject to exposure.
