From: Robina Suwol
Date: 19 Dec 2005
Time: 19:04:19
Remote Name: 69.149.40.254
The air in Fallon, Nev. has significantly higher levels of tungsten and cobalt
than does the air in neighboring towns, according to a new research report. The
research suggests that the metals in the air come from a point source within
Fallon, a community of about 8,000 located in Churchill County about 60 miles
east of Reno, Nev.
The finding that Fallon's air differs from nearby towns might have medical
implications. Since 1997, 16 cases of childhood leukemia have been diagnosed in
children who lived in the Fallon area for some time prior to diagnosis. In a
2003 U.S. Health and Human Services report investigating possible causes for the
leukemia cases in Fallon, tungsten was mentioned as "a contaminant of concern
because it was elevated in urine samples" collected from Fallon-area residents
as part of the investigation.
The metal, a component of tungsten steel and tungsten carbide, is used in tools
exposed to high temperatures, such as drill bits and the filaments of
incandescent light bulbs. 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.
"There are more metals in the air in Fallon than in other towns around Fallon.
These metals are tungsten and cobalt," said lead researcher Paul R. Sheppard, an
assistant professor of dendrochronology at The University of Arizona in Tucson.
"The biomedical ramifications of tungsten are not really all that well known."
He added that occupational exposure to cobalt has been
implicated in lung and other cancers.
The February 2004 final report of an expert panel concluded that "the cause(s)
of childhood leukemia, including those from Churchill County, Nevada, remain
unknown," and recommended further research. The National Toxicology Program is
planning studies to examine the effects of exposure to tungsten (http://www.cdc.gov/nceh/clusters/fallon/ntp_update.htm).
Sheppard and his coauthors Dr. Gary Ridenour of Fallon, Robert J. Speakman of
the University of Missouri-Columbia and Mark L. Witten, a UA research professor
of pediatrics, will publish their article, "Elevated tungsten and cobalt in
airborne particulates in Fallon, Nevada: Possible implications for the childhood
leukemia cluster," in the journal Applied Geochemistry. The Gerber Foundation
and the Cancer Research and Prevention Foundation funded the team's research.
Sheppard and Witten will give a scientific presentation about the team's
findings at 3 p.m. on Friday, Nov. 18, in room 218 of the Henry Koffler building
on the UA campus.
Because heavy metals had been suggested as one possible environmental cause of
cancers, the multidisciplinary research team tested for metals in the air of
Fallon and the four nearby Nevada towns of Reno, Fernley, Yerington and Lovelock
in the spring and fall of 2004.
The researchers placed portable air samplers at various sites in the towns. The
samplers took in a known volume of air. Dust from the air was captured on
filters and analyzed at the University of Missouri-Columbia for 19 different
metals using a technique called acid-dissolution, inductively coupled plasma
mass spectrometry. The team also analyzed wind speed and direction data from a
weather station in Fallon, because wind speed and direction can affect the
amount of dust in the air.
The team found that compared with the other towns, Fallon's air had
significantly more tungsten, and sometimes also cobalt. All five towns were
similar for the amounts of other metals in the air.
The finding suggests the source is not a natural source outside of Fallon, write
the researchers, because all the towns would likely have been similarly affected
by a natural source. Moreover, "the temporal similarity of airborne tungsten and
cobalt suggests a single source for these two metals," the researchers wrote in
their article. "However, cobalt is not abundant naturally in west-central
Nevada, and no specific deposits of both tungsten and cobalt are known near
Fallon."
Moreover, the researchers wrote, if the tungsten came from a natural source
outside Fallon, high winds would kick up tungsten-laden dust, increasing the
amount of tungsten found in the air. "However," states their research report,
"results in Fallon were exactly the opposite this: high winds resulted in lower
tungsten loading in Fallon dust, suggesting that the source is within Fallon."
Sheppard said, "In Fallon, we got high amounts of tungsten with no wind and low
amounts with high wind." He added, "There's no variability in the other towns.
These data indicate that Fallon is environmentally distinctive."
Because the air samplers were placed at various sites throughout Fallon, the
researchers could see if wind affected where tungsten was found in Fallon's air.
The research team found that the amount of tungsten and cobalt in the air was
highest near north-central Fallon and tapered off further away. According to a
February 2003 U.S. Health and Human Services report, Fallon has a facility that
"houses offices, a laboratory, and a tungsten carbide processing operation."
Sheppard said, "Our research found elevated levels of tungsten within a
three-kilometer radius of the hard-metal facility."
Witten said, "There needs to be more research done to examine the relationship
between these metals and the development of leukemia. We're doing that in my
lab. It's another step to try and identify a possible environmental cause of
leukemia."
Sheppard said, "We also need to learn more information about the biomedical
consequences of airborne tungsten."
Sheppard is now looking at tree-ring cores from the area to see if the trees can
reveal anything about the history of tungsten and cobalt in the air in Fallon.
He said, "Trees incorporate metals from the environment and those metals show up
in the tree rings. By analyzing the chemicals in tree rings, we can look back in
time years, and even decades, to learn about metals in Fallon's environment."
http://uanews.org/
Posted 18th November 2005