HR: 17:30h
AN: B12F-07    [PDF]
TI: Dendrochemistry of Urban Trees in an Environmental Exposure Analysis of Childhood Leukemia Cluster Areas
AU: * Sheppard, P R
EM: sheppard@ltrr.arizona.edu
AF: Laboratory of Tree-Ring Research, 105 West Stadium University of Arizona, Tucson, AZ 85721 United States
AU: Witten, M L
EM: mwitten@peds.arizona.edu
AF: Department of Pediatrics, Arizona Health Sciences Center University of Arizona, Tucson, AZ 85721 United States
AB: Currently in the US, there are at least two ongoing clusters of childhood leukemia, where the incidence rate over the last several years has far and away exceeded the national norm. In Fallon, Nevada, a town of 10,000 people, 16 children have been diagnosed with leukemia since 1995, three of whom have died. In Sierra Vista, Arizona, a town of 38,000 people, 11 children have been diagnosed since 1998, one of whom has died. A possible third cluster of childhood leukemia and other cancers is being monitored in Elk Grove, California, a suburb of Sacramento. For the purpose of providing a suite of many elements from which to search for temporal changes in environmental chemical availability that might have possibly contributed to these clusters, increment-core samples were collected from trees within these three communities and measured for elemental concentrations using inductively coupled plasma mass spectroscopy. Two time periods of rings were analyzed, one representing the cluster period (1997 to present) and one representing some period in the past, usually dating into the early 1980s. Among many elements that were measured, only tungsten showed a reasonably consistent change through time across the several trees that were sampled initially. In many cases, tungsten increased in the rings by as much as a doubling from past to present. The obvious dendrochemistry question applies: 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? To date, other trees sampled away from the cluster areas have shown variable changes in their tungsten concentrations, with some increasing and others decreasing through time. A CDC study of human tissue samples from Fallon showed high tungsten levels in people of Fallon, and a USGS study of drinking water in Fallon also showed high tungsten there. Filtered samples of inhalable air in Sierra Vista have more tungsten than other nearby areas of southern Arizona. Some medical research work has shown at least a possible connection between tungsten and leukemia or cancer generally.
DE: 4221 Dendrochronology
SC: Biogeosciences [B]
MN: 2003 Fall Meeting