FALLON -- A federal study of a childhood leukemia cluster in this farming and military town found high amounts of tungsten and arsenic in most residents -- but nothing to indicate that either caused the cancer.
Scientists said Thursday that elevated levels of tungsten and arsenic in tap water and biological samples are "very important findings" that will form the basis for more research. Neither has been linked to leukemia.
"We've learned a lot. But we haven't found the cause of this leukemia cluster," said Dr. Carol Rubin, head of the research team from the Centers for Disease Control and Prevention in Atlanta.
Based on Fallon results, the CDC has asked the National Institutes of Health to begin researching possible links between tungsten and cancer. The NIH is now reviewing past research and would study the heavy metal for toxic and cancerous effects, Rubin said.
Rubin released study results Thursday at a community meeting attended by about 300 people, including state legislators and families of sick children. It was the most extensive use of biological and environmental samples ever in a federal cancer cluster investigation, she said.
Since 1997, the childhood leukemia in this small town -- home of the "Top Gun" Navy fighter pilot training base -- has sickened 13 children and killed three others.
No children have been diagnosed since December 2001.
Nationally, there are an average of three cases per 100,000 people. Churchill County, where Fallon is located, has about 27,000 residents.
Fallon residents who were tested also had slightly higher amounts of six pesticides and DDE -- a byproduct of the outlawed pesticide DDT -- than the average American. But there was no difference between sickened children and others in Fallon.
The leukemia-stricken children had older fathers than other Fallon children surveyed, researchers learned.
An audience eager to hear more detailed scientific analysis asked scientists Thursday evening about other potential sources of the cancer, including everything from military radars to industrial pollution. Men and women wearing work boots and jeans sat alongside local and state politicians in suits.
They applauded once, when Capt. Brad Goetsch, commander of Fallon Naval Air Station, scolded local media and nervous residents for jumping to conclusions without first reviewing scientific data.
Arsenic occurs naturally in the Fallon area, about 60 miles southeast of Reno. The city is building a treatment center to correct the problem. Rubin advised residents to buy bottled water because of arsenic's health effects. It has been linked to skin, stomach and bladder cancer but not leukemia.
Tungsten, used to strengthen steel, was mined for years here, although the mines are shut down now. There's also a tungsten carbide plant in Fallon. Tungsten is an element used in electrical applications and as a hardening alloy.
The CDC announced in August that the metal was found in unexpectedly high levels in the urine of eight out of 10 Fallon residents tested. Nationally, one in 10 Americans has comparatively high levels. Scientists said one Fallon resident had a tungsten level more than 150 times the amount determined as high.
A University of Arizona scientist searching for links between Fallon and a smaller leukemia cluster in Sierra Vista, Ariz., said this week that his preliminary research indicates that tungsten alters the cell growth of acute lymphocytic leukemia or ALL, the disease type found in Fallon.
ALL -- the most common form of childhood cancer -- weakens blood and bone marrow, spongy tissue inside large bones. It initially causes children to tire and may make them bruise or bleed easily. It can be fatal, but most children who are diagnosed survive.
Pediatric research professor Dr. Mark Witten of the University of Arizona at Tucson initially suspected jet fuel caused the leukemia clusters in Fallon and Arizona, but shifted his research to tungsten based on preliminary federal findings.
The CDC and Nevada state epidemiologist Randall Todd cautioned that Witten's research must be duplicated and other studies conducted.
Two new federal studies will be launched within months comparing contaminant levels in Fallon with two other Nevada towns -- Lovelock and Pahrump -- and comparing DNA from sickened families to other Fallon residents.
Families say they're willing to wait.
"Of course it's frustrating. But I know they're working at it," Carinsa Rivers said before the community meeting. Her daughter Sareynah was diagnosed in March 2000 and has completed her chemotherapy to combat the life-threatening blood disease.
"I wish I'd brought my diary," said Sareynah, who was planning to celebrate her 6th birthday Friday. Pale but with sparkling eyes, she said she was to eat brownies at school and go ice skating in the evening.
She smiled and wandered away from her mother, who called out, "Don't drink the water."
Parents searching for answers have assembled an ever-shifting lineup of possible suspects. Leakage from a gas pipeline nearby ruining the water supply. Jet fuel from the fighters that train overhead. Agricultural chemicals. Some parents suspect the disease was passed as a virus from cats or cows to children.
"They're trying so hard to prove that it's not this and that, that they're not looking at other things," said Tammi Beardsley, whose 7-year-old son Zac is still undergoing treatment.
"Along the way, what if the real guy got away?"
Federal scientists acknowledge that they might have arrived too late to determine the cause.
"It's frustrating to the scientists," Rubin said. "There's nothing we wanted more than to be able to come back to the people of Fallon and show them the source."
Over the past 1Y years, the CDC tested air, dust, dirt, water, and 250 people in the Fallon area, identifying more than 300 pesticides, organic compounds and infectious diseases.
Most contaminants, including those produced by jet and auto fuel, were at levels near or below national averages.
Results from another study by the Agency for Toxic Substances and Disease Registry will be released next week. It is designed to track "pathways" of past contaminants that might no longer remain in Fallon.
"It goes in baby steps," Barbara deBraga said in describing the research. The director of Infusion Center at Churchill County Community Hospital has treated most of the sickened Fallon children.
"Slow-motion baby steps," added deBraga.
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On the Net:
Centers for Disease Control and Prevention Fallon Report: www.cdc.gov/nceh/clusters/Fallon/
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