FALLON, Nev. - At the height of her daughter's
illness, Carinsa Rivers often drove around the outskirts of this
small desert town looking for a culprit.
As unlikely as she knew it was that her naked eye would identify
the cause of the childhood leukemia that struck Sareynah Rivers
and 15 other Fallon children since 1997, her desperation demanded
that she wander by local factories and the massive Naval Air
Station Fallon and helplessly ask herself, "What made these
kids sick?"
Three have died; Sareynah, who was 4 when she became ill in
2000, and the others have endured punishing chemotherapy courses
to emerge on the mend. But while science has found ways to cure
most childhood leukemia patients, it hasn't been able to determine
with any precision why high numbers of cancer cases are sometimes
clustered within small geographic areas.
Indeed, two years into the most intensive and elaborate cancer-cluster
investigation in US history, answers remain elusive, and this
community of 26,000 people about 60 miles southeast of Reno
remains alternately anxious, angered, and exhausted by the saga.
The Centers for Disease Control, in its first such probe in
more than 20 years, tested the water, the air, and the soil
in and around homes in Fallon, and took urine and blood samples
from residents. The most compelling finding is also a perplexing
one: Fallon residents have about 13 times the national average
level of tungsten in their urine.
Tungsten is a heavy metal used to strengthen steel for warhead
tips and jet-blade rotors. But research has never linked the
element to this form of cancer and it isn't regulated by the
Environmental Protection Agency. Scientists are at odds over
the significance of the tungsten finding to the leukemia cluster.
There are dozens of inactive tungsten mines across northern
Nevada, and Fallon is home to a factory, Kennametal Inc., that
smelts tungsten ore to make tungsten carbide, a steel additive.
But it's unclear why either of the long-existing sites would
be creating a tungsten problem now.
"Tungsten has never been mentioned as a health hazard before,"
said Jan Johnson, a senior researcher at MFG Corp, an environmental
consulting firm based in Boulder, Colo., that was hired by the
City of Fallon. "There has been a lot of thought over the years
given to what materials are harmful to humans in any way, and
tungsten has never made that list."
Nonetheless, the CDC, with little else to go on, last month
directed the National Institutes of Health to research tungsten
for possible carcinogenic properties. In addition, the next
phase of the CDC's Fallon probe will involve examining the tungsten
level in the urine of people who live in two other Nevada towns,
Pahrump and Lovelock, to see whether Fallon's tungsten levels
are found in similar communities in the state without high rates
of leukemia. CDC researchers also will conduct genetic testing
to see whether some Fallon residents were made susceptible to
cancer by heredity.
"The question we ask in this type of investigation is, 'How
is this community different than other communities?' " said
Nevada state epidemiologist Randall Todd, who asked the CDC
to come after two Democratic senators, Harry Reid, of Nevada
and Hillary Rodham Clinton, of New York, held a field hearing
on the Fallon cluster in 2001 for the Committee on Environment
and Public Works. "One of the ways it is different is the tungsten
levels."
Such an approach rankles critics of cancer-cluster investigations,
who view them as wastes of money spent to satisfy upset parents.
Cluster investigations are usually fruitless, such critics assert,
because they desperately seek causes after cancers occur instead
of the more objective approach of studying various chemicals
as a matter of course just to see whether they cause diseases.
"To say that studying excess cancer in one community is going
to tell us anything about the etiology of cancer, that's very
hard to defend," said Alan Bender, section chief of chronic
disease and environmental epidemiology in the Minnesota Department
of Public Health.
Bender's view is countered by Richard Klapp, the Boston University
epidemiologist who in the 1980s found that the contaminant trichloroethylene
in the water in Woburn probably sparked a cancer cluster there.
That case inspired the film "A Civil Action."
"Some people will say you haven't proved these kids actually
ingested this water during this time period, and until you can
show us that, we won't believe it," Klapp said. "What constitutes
a smoking gun? Whatever the statistical unlikelihood is, you
have to investigate. When there is a plausible exposure, that
requires follow-up."
In fact, the CDC's interest in tungsten is backed up by independent
work by University of Arizona toxicology researcher Mark Witten,
who found that tungsten levels in Fallon's tree rings were up
45 percent between 1997 and 2001 compared with the levels from
1980 to 1984. That implies a change over time that has specialists
puzzled.
"There is an explanation," said Carol Rubin, head of the CDC's
investigation."We just haven't figured it out yet and we don't
know if it's relevant to the cluster."
Another cancer-stricken community, Sierra Vista, Ariz., is
anxious to see the outcome of the Fallon probe and the tungsten
inquiries. Ten leukemia cases have been diagnosed in Sierra
Vista since 1995, about three times the norm for a community
of 39,000.Witten also found a 75 percent increase in the tungsten
levels in trees in Sierra Vista in 1997 to 2001 as compared
with 1980 to 1984. Fallon's rate was at least five times the
norm.
Sierra Vista has other striking similarities to Fallon: It's
also a rural, high-desert town in a valley with nearby inactive
tungsten mines, and it's home to a military base with an airport
- the Fort Huachuca Army Base. Both Huachuca and Naval Air Station
Fallon use munitions that contain tungsten.
"My research right now tells me tungsten is the prime suspect,"
Witten said.
"I want to see if all these leukemia clusters have environmental
components. Maybe it's tungsten when it combines with something
else. Really, very little is known."
Witten's bluntness has earned him critics in the scientific
community and ardent supporters among parents who say the CDC
is too cautious.
"The only person doing a legitimate investigation of this
is Mark Witten," said Floyd Sands, whose 19-year-old daughter,
Stephanie, was the first to die in the Fallon cluster, in September
2001. "I don't think that tungsten itself causes cancer, but
those elevated levels may point to something else."
Rivers, 26, doesn't know what to think anymore. She had never
heard of tungsten until about a year ago, and she tries to pay
less attention to the issue now that Sareynah is in remission.
She says she hasn't considered moving away, even though she
has a 2-year-old son as well.
"I'm hoping they find something, but I'm not getting my hopes
up," Rivers said."But they can't ever stop looking."
