Using high-precision multicollector mass spectrometry for the first time in such a study, Robert Haley, M.D., director of the division of epidemiology at UTSW, and Randall Parrish, Ph.D., professor of isotope geology at the University of Portsmouth in England, collaborated to examine a representative sampling of veterans' urine maintained by UT Southwestern's Gulf War Illness Research program. Their report found no differences in secretion of uranium isotopic ratios from those meeting the standard-case definitions of GWI and control veterans without GWI.