Previous research by Sheppard and his colleagues found elevated levels of tungsten and cobalt in airborne and surface dust and in lichens in Fallon.

The researchers also analyzed airborne tungsten particles from Fallon to determine their source. The analysis found that the particles "were anthropogenic in origin, not natural." The particles were relatively uniform in size, ranging from about 1.0 to 5.9 micrometers in diameter.

Particles less than 10 micrometers in diameter are small enough to be inhaled and have potential to cause health problems, according to the U.S. Environmental Protection Agency. (http://www.epa.gov/air/particlepollution/)

The research team's study on the characteristics of the tungsten particles has been accepted for publication by the journal Microscopy and Microanalysis.

Fallon is a community of about 8,000 located in Churchill County about 60 miles east of Reno, Nev. Tungsten is naturally present in soils and rocks in Churchill County and other parts of Nevada.

The metal was mined in the region around Fallon at various sites, including Churchill Butte. Tungsten, tungsten steels and tungsten carbide are used in hardened tools and tools exposed to high temperatures, such as drill bits and the filaments of incandescent light bulbs.

The increase in Fallon's childhood leukemia began around 1997. Heavy metals had been suggested as one possible environmental cause of cancers, so Ridenour and Witten began investigating how to conduct research on Fallon's environment.

Witten approac
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Contact: Mari N. Jensen
mnjensen@email.arizona.edu
520-626-9635
University of Arizona
30-Apr-2007