Tungsten began increasing in trees in Fallon, Nev. several years before the town's rise in childhood leukemia cases, according to a new research report.
The amount of tungsten in tree rings from Fallon quadrupled between 1990 and 2002, whereas the amount in tree rings from nearby towns remained the same, according to a research team led by Paul R. Sheppard of The University of Arizona's Laboratory of Tree-Ring Research.
This is the first study that has examined changes in levels of heavy metals in Fallon over time.
"Trees take up metals from the environment and those metals show up in the tree rings. By analyzing chemicals in tree rings, we can look back in time years, and even decades," said Sheppard, a UA assistant professor of dendrochronology.
"Tree ring values for the early 1990s for tungsten are roughly equivalent to nearby towns, but go up in Fallon in the mid-1990s while staying the same in other towns," he said.
Tungsten levels in Fallon trees began increasing in 1994, while levels in neighboring towns remained the same. Since 1997, 17 cases of childhood leukemia have been diagnosed in children who lived in the Fallon area for some time prior to diagnosis. Fallon's high incidence of leukemia has been acknowledged as a leukemia cluster by the Nevada State Health Division. (http://health.nv.gov/index.php?option=com_content&task=view&id=356&Itemid=595 )
The tree-ring study by Sheppard and his co-authors Robert J. Speakman of the Smithsonian Institution in Suitland, Md., Dr. Gary Ridenour of Fallon and Mark L. Witten, a UA research professor of pediatrics, is in the May 2007 issue of Environmental Health Perspectives.
A list of funding sources and the complete citation for the article is at the bottom of this release.