Reply to comment on "Elevated tungsten and cobalt in airborne particulates in Fallon, Nevada: Possible implications for the childhood leukemia cluster", by Blasland, Bouck & Lee, Inc.

Several criticisms of Sheppard et al. (2006a) are raised in this comment. One, airborne W and Co loadings are expressed as mass of element per volume of air rather than mass of element per mass of dust and therefore cannot be reasonably interpreted. Two, inter-seasonal patterns of airborne W and Co in Fallon seem inconsistent. Three, the role of wind direction on airborne W and Co in Fallon is not clear. Four, elevated levels of airborne W and Co in Fallon do not approach threshold limits of exposure established for workplaces. Five, children of Fallon do not necessarily live near the hard-metal facility in Fallon and therefore are not exposed to elevated airborne W and Co. Six, research on total suspended particulates of Fallon was not warranted because airborne W in Fallon had been studied already. The authors respond to these criticisms as well as to additional points made in this comment.