Depleted uranium exposure and health effects in Gulf War veterans

Abstract

Health effects stemming from depleted uranium (DU) exposure in a cohort of Gulf War veterans who were in or on US Army vehicles hit by friendly fire involving DU munitions are being carefully monitored through the Baltimore Veterans Affairs (VA) DU Follow-Up Program initiated in 1993. DU exposure in this cohort has been directly measured using inductively coupled plasma-mass spectrometer (ICP-MS) isotopic analysis for DU in urine specimens. Soldiers with embedded DU fragments continue to excrete elevated concentrations of U in their urine, documenting ongoing systemic exposure to U released from their fragments. Biennial surveillance visits provide a detailed health assessment that includes basic clinical measures and surveillance for early changes in kidney function, an expected target organ for U. Tests also include measurements of genotoxicity and neuroendocrine, neurocognitive and reproductive function. With the exception of the elevated urine U excretion, no clinically significant expected U-related health effects have been identified to date. Subtle changes in renal function and genotoxicity markers in veterans with urine U concentrations greater than 0.1 microg(-1) creatinine, however, indicate the need for continued surveillance of these DU-exposed veterans.

Figure 1

Whole body radiation counting results for ‘DU-exposed’ and ‘Non-DU-exposed’ Gulf War veterans participating in the Baltimore VA DU Follow-Up Program. Participants are ranked from low to high along the x-axis based on their whole body ranking scores (WBCS; McDiarmid et al. 2000). Measurements from only nine of the 27 veterans in the ‘DU-exposed’ cohort were above the limit of detection.

Figure 2

Uranium concentrations in 24 h urine specimens distributed from low to high for Gulf War veterans participating in the DU Follow-Up Program surveillance visit in 2005. The top two lines (65.1and 9.1 μg l⁻¹) represent the mean total urine uranium found in a sub-cohort of uranium fabrication workers in 1975 and 1980, as reported in a study by Thun et al. (1985). The alternating dot/dash line (0.8 μg l⁻¹) depicts an occupational exposure decision level used at the Department of Energy's Fernald Environmental Management Project (Fernald Environmental Management Project 1997; McDiarmid et al. 2000) as a trigger for investigating work areas for sources of elevated uranium exposure. The dotted line (0.365 μg l⁻¹) is an upper limit for the dietary contribution of uranium in urine for the general population from drinking water (ICRP 1974; McDiarmid et al. 2000). This value was calculated by dividing the upper limit for 24 h uranium excretion for ‘reference man’ by 1.4 l 24h⁻¹. Studies have shown that corrections per gram creatinine and per litre urine are generally equal for ‘reference man’ and for this group of veterans with normal renal function (Ting 1999; NHANES 2003). The bold solid line (0.01 μg g⁻¹ creatinine) indicates the cut point established by the DU Follow-Up Program to identify low versus high urine uranium concentrations (McDiarmid et al. 2000). Designation of natural versus depleted uranium is based on isotopic ratio results.

Figure 3

Mean, maximum and minimum urine uranium concentrations for 27 Gulf War veterans with at least four urine samples submitted between 1993 and 2005. Results for individual veterans are distributed from low to high based on their mean urine U concentration. Urine uranium excretion has remained elevated over the 14 years since the Gulf War for most veterans with above normal urine uranium concentrations (greater than 0.10 μg g⁻¹ creatinine).