In this study that revisited their previous results, McDiarmid and colleagues identified 30 new members of the originally exposed group. Urinary uranium concentrations were measured, and correlation analyses were conducted to determine the relationship between excretion measures in the 1994, 1997, and 1999 surveillance groups.
An increase in urinary uranium (24-hour urinary uranium concentrations higher than 0.05 μg/g of creatinine) was observed in four of the 30 newly identified veterans. Urinary uranium showed a high correlation (R-squared [rsq] = 0.8623) between the 1994 assessment and the 1997 assessment. A strong correlation (rsq = 0.8764) was also observed between the 1994 and the 1999 assessments.
In the third surveillance, 39 Gulf War veterans were examined at the Baltimore VAMC during April-July 2001. Of the 39, eight were identified as new participants, and the remaining 31 had participated in the followup program at least once before. As in earlier studies, the authors investigated a number of clinical outcomes as related to urinary uranium concentrations 10 years after the initial exposure to uranium. In addition to the clinical measures assessed previously (McDiarmid et al., 2000, 2001), the evaluation considered immunologic measures and mutagenic effects related to depleted-uranium exposure by assessing HPRT mutation frequency. The 29 participants with no history in the Depleted Uranium Follow-up Program were also evaluated for posttraumatic stress disorder and substance abuse. The exposure groups were defined on the basis of participants’ 2001 urinary-uranium results. Thirteen participants were in the high-exposure category (with concentrations greater than 0.10 μg/g of creatinine), and 26 in the low-exposure category.
Neurocognitive test batteries were similar to those used previously (McDiarmid et al., 2001). Automated measures were selected from the Automated Neuropsychological Assessment Metrics Test Library. The authors constructed four indexes of impairment based on the traditional tests and the automated measures (response accuracy, median response time for correct response, and number of correct responses per minute or throughout). The indexes represent the proportion of scores that fell 1 standard deviation below the mean. The BDI was used to evaluate emotional status. Genotoxic tests were adjusted for potential confounders (age, smoking, exposure to genetic toxicants, and cloning efficiency).
Urinary uranium ranged from 0.001 to 78.125 μg/g of creatinine. The presence of retained depleted-uranium shrapnel appeared to be associated with higher urinary uranium concentration. In addition, most urinary-uranium results were fairly consistent throughout a given person’s history in the group.