412 Dendrochemistry of Urban Trees in An Environmental Exposure Analysis of a Childhood Leukemia Cluster

Friday, November 6, 2009: 11:20 AM
Santa Fe (Camino Real Hotel)
Paul R. Sheppard , Laboratory of Tree-Ring Research, University of Arizona, Tucson, AZ
Mark L. Witten , Department of Pediatrics, University of Arizona, Tucson, AZ
Dendrochemistry, the measurement of chemical elements in tree rings for the purpose of assessing chemical environments through time, was done in Fallon, Nevada, a small town that experienced a cluster of childhood leukemia from the late 1990s through 2004.  Increment-core samples were collected from trees within Fallon as well as other communities for comparison, and tree rings were measured for elemental concentrations using inductively coupled plasma mass spectroscopy.  Multiple time periods of rings were analyzed representing the cluster period (1997 to present) as well as in the past back to the late 1980s.  Among many elements that were measured, tungsten showed changes through time across the several trees that were sampled in Fallon.  Other bio-indicator evidence of environmental chemistry shows airborne tungsten to be elevated currently within Fallon.  A dendrochemistry question arises: Does this increase in tungsten through time in tree rings represent a true increase in environmental exposure to tungsten, or is it merely an internal physiological phenomenon?  Additional replication will be needed to confirm this temporal finding about tungsten, but this is an interesting start.  Medical research work has shown at least a possible connection between tungsten and leukemia or cancer generally.