Scientists studying childhood leukemia cases in Arizona and Nevada say their research shows a possible link between tungsten and the disease.

University of Arizona researchers Mark Witten and Paul Sheppard said a small group of laboratory mice developed leukemia-like blood symptoms after they were exposed to the heavy metal and then a common respiratory virus.

The two have been investigating childhood leukemia clusters in Sierra Vista, Ariz., and Fallon, a rural community 60 miles east of Reno, since 2002.

Since 1997, 17 children in Fallon were sickened with leukemia. Three died. The last case in the cluster was diagnosed in 2004.