Tungsten probably is not the main cause of a Fallon leukemia cluster that has sickened 16 children and killed three since 1997, federal scientists said.
The federal Centers for Disease Control and Prevention found that the metal shows up in elevated levels all over Nevada, including areas where leukemia cases are within normal ranges.
Tungsten had been suspected of causing the Fallon outbreak because it turned up in unusually high levels in the area's population.
Tests this year also showed high levels of tungsten in residents of Yerington, Pahrump and Lovelock, but the communities have shown normal levels of leukemia cases.
"This decreases the probability that tungsten is the cause" of the Fallon outbreak, state epidemiologist Randall Todd told the Las Vegas Review-Journal.
Despite the findings, government scientists did not rule out tungsten as a contributing factor in the Fallon outbreak.
The metal might act in combination with something else present in the small Navy and farm town 60 miles east of Reno, Todd said.
Mark Witten, an Arizona toxicologist who has been studying tungsten in tree rings in communities with cancer clusters, said he still thinks the metal is a prime suspect in the Fallon cluster.
His team has found increasing tungsten levels in tree rings in four such communities: Fallon; Sierra Vista, Ariz.; Sacramento County, Calif., and Hoisington, Kan.
"Four out of four areas where there are leukemia clusters are showing increasing tungsten levels over time, and yet we're not seeing the same kind of consistent increases in trees in Lovelock or Fernley," Witten told the Reno Gazette-Journal.
Tungsten is naturally occurring in the Fallon area, and tungsten ore was smelted in an open-air kiln 10 miles north of Fallon for three decades.
While they're not yet ready to say the investigation into the Fallon cluster is over, state health officials acknowledge it's winding down - without definitive results.
"We will probably put the investigation itself into stasis now and just be in surveillance mode," Todd said.
The move to slow the investigation does not surprise Floyd Sands, whose daughter, Stephanie, died of leukemia in 2001.
"They haven't done a damn thing right from the get go," he said. "What do you expect from the CDC? ... I've always felt that if we were going to get answers, it wouldn't be from a government agency."
The CDC has investigated 108 cancer clusters across the country and not figured out a cause, Sands added.
Todd said he would reconvene an expert panel that was formed when the cluster was discovered three years ago to help determine the next step for state officials.
"My expectation is that they're going to say, `You have done all you can do,"' Todd said.
(Copyright 2003 by The Associated Press. All Rights Reserved.)