Squibb Katherine S, Leggett Richard W, McDiarmid Melissa A
Department of Epidemiology and Preventive Medicine, University of Maryland School of Medicine, Baltimore, MD 21201, USA.
Health Phys. 2005 Sep;89(3):267-73. doi: 10.1097/01.hp.0000165451.80061.7e.
Mobilization of uranium (U) from embedded depleted uranium (DU) metal fragments in Gulf War veterans presents a unique exposure scenario for this radioactive and nephrotoxic metal. In a cohort of exposed veterans, urine U concentrations measured every two years since 1993 persistently range from 10 to over 500 times normal levels, indicating that embedded DU fragments give rise to chronic, systemic exposure to U. Health effects of this exposure are not fully known, but clinical surveillance of these soldiers continues in light of animal studies showing that U released from implanted DU pellets results in tissue accumulation of U. The biokinetic model for uranium recommended by the International Commission on Radiological Protection was used to predict kidney U concentrations and tissue radiation doses in veterans with DU shrapnel based on their urine U excretion. Results suggest that kidney U concentrations in some individuals reached their peak within six years after the war, while in others, concentrations continue to increase and are approaching 1 ppm after 10 y. These results are consistent with urine biomarker tests of renal proximal tubular cell function and cytotoxicity which have shown elevated mean urinary protein excretion indicative of functional effects in veterans with high urine U concentrations (> or =0.10 microg g(-1) creatinine). Predicted lifetime effective radiation dose from DU released to the blood for the highest exposed individual in this cohort was substantially less than the National Council on Radiation Protection (NCRP) limit for occupational exposure. These results provide further support for current health protection guidelines for DU, which are based on the metal's chemical rather than its radiological toxicity. In light of the potential for continued accumulation of U in the kidney to concentrations approaching the traditional guidance level of 3 ppm U, these results indicate the need for continued surveillance of this population for evidence of developing renal dysfunction.
海湾战争退伍军人体内嵌入的贫铀（DU）金属碎片中铀（U）的动员，为这种具有放射性和肾毒性的金属带来了独特的暴露情况。在一组暴露的退伍军人中，自1993年以来每两年测量一次的尿铀浓度持续比正常水平高10至500倍以上，这表明嵌入的贫铀碎片导致了对铀的慢性、全身性暴露。这种暴露对健康的影响尚不完全清楚，但鉴于动物研究表明植入的贫铀弹丸释放的铀会导致组织中铀的积累，对这些士兵的临床监测仍在继续。国际放射防护委员会推荐的铀生物动力学模型，被用于根据退伍军人的尿铀排泄情况预测有贫铀弹片的退伍军人肾脏中的铀浓度和组织辐射剂量。结果表明，一些人的肾脏铀浓度在战后六年内达到峰值，而另一些人的浓度则持续上升，10年后接近1 ppm。这些结果与肾近端小管细胞功能和细胞毒性的尿生物标志物测试结果一致，这些测试表明，尿铀浓度高（≥0.10 μg g⁻¹肌酐）的退伍军人平均尿蛋白排泄量升高，表明存在功能影响。该队列中暴露最高的个体因贫铀释放到血液中预测的终生有效辐射剂量，大大低于美国国家辐射防护委员会（NCRP）的职业暴露限值。这些结果为当前基于贫铀金属化学毒性而非放射毒性的健康防护指南提供了进一步支持。鉴于肾脏中铀可能继续积累至接近3 ppm铀的传统指导水平，这些结果表明需要继续监测这一人群，以寻找肾功能恶化的证据。
