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5 Exposure Assessment H uman eï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ xposure assessment is a key component inï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ understandï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ ing whether depleted uraniumï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ can cause specific health outcomesï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ .ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ Most of this chap- ter summarizes three reportsâthe âCapstone reportâ (USACHPPM, 2004), the âSandia reportâ (Marshall, 2005), and the âRoyal Society reportâ (Royal Society, 2001). Those reports used models to estimate depleted-uranium exposures in military personnel of the Gulf War. Information about exposures to depleted uranium that probably occurred in Gulf War troops will help to put health outcomes observed in epidemiologic studies described in Chapter 7 into context. There are several methods for monitoring depleted uranium in the body, and the reminder of this chapter describes how depleted uranium is detected in humans. Estimation of Exposure to Depleted Uranium During the Gulf War Depleted-uranium penetrator strikes can produce inhalable aerosols that contain high concentrations of depleted uranium and depleted-uranium fragments that can cause shrapnel wounds (DOD, 2000). Substantial amounts of aerosol can be generated when a depleted-uranium penetrator strikes military vehicles, such as Abrams tanks and Bradley vehicles. The residual level of depleted uranium is affected by the vehiclesâ ventilation rates. Ingestion of depleted-uranium particles in contaminated vehicles is possible but probably is not an important exposure route. 93
94 updated literature review of depleted uranium Exposure to depleted-uranium aerosols can be affected by characteristics of the struck vehicle, impact conditions, and residence time of personnel in the contaminated vehicle. If the target is soft (such as a lightly armored vehicle), the depleted-uranium penetrator is likely to pass through it with little conversion of the penetrator rod into depleted-uranium oxides (Royal Society, 2001). If a pen- etrator strikes the depleted-uranium armor of a modern battle tank, much of the penetrator mass will be converted into depleted-uranium oxides. When a modern battle tank, such as an Abrams tank, is involved in a âfriendly-fireâ incident, sub- stantial amounts of depleted-uranium aerosols can be generated by the impact. During friendly-fire incidents, various exposure scenarios occurred. To cat- egorize the exposure levels, exposures to depleted uranium during the Gulf War have been classified into three categories (DOD, 2000; USACHPPM, 2000), which provide a useful framework for considering potential depleted-uranium intakes and associated risks that was used in the Capstone report (USACHPPM, 2004), the Sandia report (Marshall, 2005), and the Royal Society report (Royal Society, 2001). The three categories are defined here. â¢ Level I includes military personnel in, on, or near combat vehicles at the time of impact and perforation by depleted-uranium munitions or personnel who entered vehicles immediately after they were struck (and perforated) by depleted- uranium munitions. The personnel could have been exposed to depleted uranium by contact with fragments resulting from impact or their being embedded in the body, by inhalation of depleted-uranium aerosols, by ingestion of depleted- uranium residues, or by settling of depleted uranium particles on open wounds, burns, or other breaks in the skinâor by any combination of these possibilities. This level also includes personnel occupying a vehicle whose depleted-uranium armor is perforated by nonâdepleted-uranium munitions. â¢ Level II includes military personnel and a small number of Department of Defense (DOD) civilian employees whose job functions required them to work in and around vehicles that contained depleted-uranium fragments and particles. Those people were not in a vehicle at the time of impact and did not immediately enter it after it was struck. They performed a variety of tasks, such as battle- damage assessment, repairs, explosive-ordnance disposal, and intelligence- g Â athering. They typically entered vehicles well after the initial suspended aerosol had dissipated or settled onto interior surfaces. They may have inhaled depleted- uranium residues that were resuspended by their physical activities, ingested depleted uranium through hand-to-mouth transfer, or spread contamination on their clothing. DOD personnel who were involved in cleaning up depleted- u Â ranium residues generated during other events, such as the July 11, 1991, explosion and fires at the Camp Doha North Compound, are also included in this group. â¢ Level III is an âall othersâ group whose exposures were brief or Âincidental. This group includes personnel who entered depleted-uraniumâcontaminated Iraqi equipment, were downwind of burning Iraqi or US equipment struck by depleted-
EXPOSURE ASSESSMENT 95 uranium rounds, or were downwind of burning depleted-uranium ammunition (such as personnel at Camp Doha during the July 11, 1991, explosions and fire). Although these people could have inhaled airborne depleted-uranium par- ticles, they are unlikely to have received an intake high enough to cause health effects. Level III exposure is likely to be much lower than level I or II exposure. However, the number of military personnel with level III exposure may be much larger and the exposure range wider. Direct measurement of exposure to depleted uranium in the battlefield is ideal but is not practical. To estimate exposure, field tests have been conducted to measure the range of depleted-uranium concentrations in vehicles that have been struck by large-caliber depleted-uranium rounds (USACHPPM, 2004). Aerosols were collected while Abrams tank and Bradley vehicle ballistic hulls and turrets with depleted-uranium armor or conventional armor were struck by depleted- uranium rounds. When an Abrams tank with depleted-uranium armor was struck, inhalation intake of depleted-uranium oxides by surviving crew members in 5 min- utes is estimated to have been 20% greater than intake by the crew of a tank with conventional armor. When the less heavily armored Bradley vehicle was struck, inhalation intake was estimated to be 30% of the intake in the Abrams tank. Residual concentration in a struck vehicle can be affected by ventilation of the vehicle. In one field test, inhalation intake of depleted uranium was reduced by about 90% in a struck Abrams tank with an operating ventilation system com- pared with that in a tank without one (USACHPPM, 2004). However, it is not clear whether the ventilation systems were active during friendly-fire incidents in the Gulf War. Without confirmed information on ventilation, estimation of exposure should be based on the cautious assumption of no ventilation. All three reports mentioned aboveâthe Capstone report, the Sandia report, and the Royal Society reportâwere based on an estimation approach, so they are all subject to considerable uncertainties in intake estimates and due to parameters chosen for modeling. The Royal Society report used the best data then available on initial air concentrations of depleted-uranium oxides in a struck tank and pro- duced central estimates of intakes and risks for a number of exposure scenarios. Worst-case estimates were also provided by using values at the upper end of the likely range. The worst-case scenarios provide intakes and risks that are unlikely to be exceeded. The Capstone report addressed inadequacy of the available data from test firings by conducting 13 new test firings of large-caliber depleted-uranium rounds against an Abrams tank and a Bradley vehicle. The Capstone study determined the airborne depleted-uranium concentration and size distribution in the struck vehicles as functions of time after impact. It provides a substantial database of airborne depleted-uranium concentration in struck vehicles and of the composi- tion and particle size distribution. In addition, in vitro solubility of particles in the
96 updated literature review of depleted uranium aerosol allowed estimates of the likely intake of depleted uranium and health risk. A National Research Council committee reviewed and evaluated the Capstone report and concluded that the âmethods and results of the Capstone exposure assessment to be appropriate and well doneâ (NRC, 2008). The Sandia report independently analyzed the Capstone test-firing data, estimated intakes by soldiers on the battlefield, and provided predicted risks to health. The Capstone and Sandia reports provide typical intakes and maximum intakes based on the highest observed value in test firings. Direct comparison of the three reports is complicated by use of different methods, terminologies, and parameters. However, all three reports agree on the general extent of the intakes from and health risks posed by depleted uranium. Level I Exposures Each of the three reports estimated level I exposure through inhalation by modeling with data from test firings. The data from the Capstone test firings showed a range of inhalation intakes of 250-710 mg of depleted uranium by the surviving crews of an Abrams tank struck by a single large-caliber depleted- uranium penetrator. The range for first responders was 150-200 mg. The Sandia study reported a best estimate of 250 mg and a maximum of 4 g on the basis of the Capstone test-firing data, which are almost identical with those in the Royal Society report. The three reports had similar estimates of peak renal uranium concentra- tion. A comparison of the level I exposure estimates is shown in Table 5-1. The best estimates of 3 Âµg/g of kidney and up to 6.5 Âµg/g of kidney were reported in the Sandia study and the Capstone study, respectively. The central peak of 4 Âµg/g of kidney was reported in the Royal Society report. The worst-case renal concentration of 400 Âµg/g in the Royal Society study and the maximum of 53 Âµg/g in the Sandia study suggest that kidney failure is possible under extreme circumstances. It is generally accepted that the risk of developing cancer is related to the radiologic dose. Internal exposure to alpha radiation, such as from deposited depleted-uranium aerosols, may increase the risk of cancer. Each report provided an effective dose based on a period of 50 years after exposure. The predicted increase in lifetime risk of death from lung cancer from level I exposure is about 0.1% in the Royal Society and Sandia reports and 0.06-0.3% in the Capstone report. An increase risk of 0.1% implies that the chance over a personâs lifetime of dying of lung cancer from level I exposure is 0.1% greater than the background rate of cancer mortality. The worst-case estimate of lung cancer in the Royal Society report was 6.5%. The maximum estimates were 3.5% and 0.4-1.4% in the Sandia report and the Capstone report, respectively. The increase in lifetime risk of other fatal cancers, including leukemia, is much lower than the increase in risk of lung cancer.
EXPOSURE ASSESSMENT 97 TABLE 5-1â Comparison of Level I Exposure Estimates and Risk Capstone Sandia Royal Society (Maximum) (Maximum) (Worst Case) Estimated inhalation 160-710 mg (1 g) 250 mg (4 g) 250 mg (5 g) intake of depleted uranium Peak renal uranium 0.7-6.5 (16) Î¼g/g 3 (53) Î¼g/g of kidney 4 (400) Î¼g/g of of kidney kidney Effective dose 0.9-6.0 rems 15 mSv (250) by 22 mSv (1,100) or 9-60 mSv inhalation only Inhalation and 19 mSv (265) by ingestion inhalation and fragment Excess lifetime risk 0.06-0.3% (0.4%)c 0.085% (1.4%) 0.12% (6.5%) of lung cancera Excess lifetime risk NA 0.0004% (0.007%) 0.0005% (0.005%) of leukemiab NOTE: NA = not available. aLifetime risk of lung cancer: 7.91% in US men, 6.18% in US women (ACS, 2008). bLifetime risk of leukemia: 1.50% in US men, 1.06% in US women (ACS, 2008). cSpratt, 2007. In addition to inhalation intake, depleted-uranium shrapnel wounds consti- tute a potential exposure route for those involved in level I exposure scenarios. In the Gulf War, 6 Abrams tanks and 15 Bradley vehicles were involved in friendly- fire incidents. The total number of soldiers surviving those incidents was 104. The Baltimore Department of Veterans Affairs health-surveillance program recruited and followed this depleted-uraniumâexposed cohort. A total of 74 soldiers have participated in at least one visit since 1993. Of the 74, 19 have evidence of retained shrapnel as indicated by skeletal X-ray analysis. Whole-body radiation counting was conducted in 29 depleted-uraniumâ exposed soldiers, including those with shrapnel (McDiarmid et al., 2000). Only nine have detectable scores above the background provided by the counting chamber, and all nine had shrapnel. The lack of sensitivity may be due to the low radioactivity of uranium and the tissue absorption of depleted-uranium radiation. Another way to estimate uranium exposure is on the basis of urinary uranium excretion. Urinary uranium concentration can be a biomarker of total cumulative dose. An occupational-exposure decision level of 0.8 Âµg/L is used by the Depart- ment of Energy Fernald Environmental Management Project (FEMP, 1997). The
98 updated literature review of depleted uranium soldiers with shrapnel continue to excrete high levels of uranium. The mean concentration in depleted-uraniumâexposed soldiers is well above an upper-limit value that occurs in a normal population owing to intake of natural uranium in drinking water (0.365 Âµg/L) (ICRP, 1974) and above the occupational-exposure decision level of 0.8 Âµg/L as a trigger for investigating work areas for unsuspected high exposure to uranium. Radiation dose to the depleted-uraniumâexposed cohort was estimated by using urinary uranium-excretion data for a 10-year period after the Gulf War (Squibb et al., 2005). The upper bound of estimated lifetime (50-year) radia- tion dose of the depleted-uraniumâexposed soldier who had the highest urinary concentration was 60 mSv, which is close to the National Council on Radiation Protection and Measurements allowable radiation dose for the public of 50 mSv (NCRP, 1993) and the US Nuclear Regulatory Commissionâs regulations for occupational dose to individual adults of 50 mSv/year (10 CFR 20.1201). Level II Exposures Level II exposures depend on the amount of time spent working in contami- nated vehicles. The exposure estimates are based on a single acute intake and assume that personal protective equipment is not used and that decontamination has not taken place before the personâs entry into the vehicle. Central or best esti- mates are based on 10 hours of work in contaminated vehicles. Estimated inhala- tion intakes in the Capstone, Sandia, and Royal Society reports were 5-40 mg, as shown in Table 5-2. Peak renal uranium concentrations were 0.03-0.5 Âµg/g of kidney. The Capstone study reported effective dose in rems per hour; this requires that the total time in the vicinity of the depleted-uraniumâperforated vehicle and the fraction of time in the vehicle be known. The Sandia and Royal Society stud- ies estimated effective doses from depleted-uranium exposure scenarios based on a 50-year postexposure duration. Lung-cancer risks are at least fivefold less than the corresponding level I estimate. Maximum and worst-case level II estimates are based on 100 hours of work in a contaminated vehicle. Excess lifetime lung- cancer risks are 0.2-0.4% in the Capstone and Sandia reports and 2.4% in the Royal Society report. Level III Exposures Level III exposures can result from briefly entering a contaminated vehicle, from exposure to plumes downwind of penetrator impacts, and from exposure to resuspended soil. The health risks associated with level III exposure are pre- dicted to be very low. Estimated inhalation intakes in the Capstone, Sandia, and Royal Society reports were 0.5-6 mg, as shown in Table 5-3. Most soldiers on the battlefield may have level III exposure or less. Peak renal uranium concentration in a worst-case scenario could lead to some renal dysfunction. The excess risks
EXPOSURE ASSESSMENT 99 TABLE 5-2â Comparison of Level II Exposure Estimates and Risk Capstone Sandia Royal Society (Maximum) (Maximum) (Worst Case) Estimated inhalation 5 mg (1.45 g) 40 mg (0.6 g) 10 mg (2 g) intake of depleted uranium Peak renal uranium 0.03 (14) Âµg/g of kidney 0.5 (8) Âµg/g of 0.05 (96) Âµg/g concentration kidney of kidney Effective dose 0.00197 rem/hour (0.078) 2.5 mSv (38) 0.52 mSv (440) Additional 0.000707 rem/hour by ingestion Excess lifetime risk 0.001% (0.4%) 0.014% (0.21%) 0.0025% of lung cancera (2.4%) Excess lifetime risk NA 0.0001% (0.001%) <0.00001% of leukemiab (0.001%) NOTE: NA = not available. aLifetime risk of lung cancer: 7.91% in US men, 6.18% in US women (ACS, 2008). bLifetime risk of leukemia: 1.50% in US men, 1.06% in US women (ACS, 2008). TABLE 5-3â Comparison of Level III Exposure Estimates and Risk Capstone Sandia Royal Society (Maximum) (Maximum) (Worst Case) Estimated inhalation 0.5 mg (145 mg) 6 mg (60 mg) 1 mg (200 mg) intake of depleted uranium Peak renal uranium 0.003 (1.4) Âµg/g of Negligible (0.08) Âµg/g 0.005 (10) Âµg/g of kidney of kidney kidney Effective dose 0.00197 rem/hour 10-5 mSv (0.05) 0.09 mSv (66) (0.078) Additional 0.00012 From all pathways rem/hour by ingestion Excess lifetime risk 0.0001% (0.04%) <0.0001% (0.002%) <0.0001% (0.02%) of lung cancera Excess lifetime risk NA <0.00001% (0.00001%) <0.00001% (0.00001%) of leukemiab NOTE: NA = not available. aLifetime risk of lung cancer: 7.91% in US men, 6.18% in US women (ACS, 2008). bLifetime risk of leukemia: 1.50% in US men, 1.06% in US women (ACS, 2008).
100 updated literature review of depleted uranium of lung cancer and leukemia from level III exposure were less than 0.0001% and less than 0.00001%, respectively. In addition to battlefield exposure, there are concerns about long-term expo- sure of residents in areas where depleted-uranium munitions were deployed. Depleted-uranium penetrators might miss their intended targets and end up embedded several feet in the ground, so they could lead to increased uranium concentrations in soil and water supplies. Some depleted-uranium oxides can be resuspended and cause inhalation exposure. Such environmental exposure can cause long-term exposure in the local population. Estimation of such exposure requires understanding of different exposure pathways and information about environmental contamination. The Royal Society and Sandia reports estimate intakes and risks in the gen- eral population where depleted-uranium munitions were deployed. Cancer risks to the local population from long-term inhalation are estimated to be extremely low in both reports, even in the worst-case scenario. A worst-case estimate of uranium at 0.1-0.2 Âµg/g of kidney was reported by the Royal Society. High con- centrations of depleted uranium around sites of penetrator impacts may present some risks to children playing in these areas for long periods. The Sandia report estimates an excess lifetime risk of fatal lung cancer of 0.035% in children who play for 300 hours in and 700 hours outside a depleted-uraniumâcontaminated vehicle. Exposure-Monitoring Methods Occupational exposure and environmental exposure to depleted uranium as used in the military are the primary subjects of this report. Military personnel may be at risk of inhaling airborne depleted-uranium particles, ingesting depleted- uranium particles from contaminated vehicles, and having wounds become contaminated with depleted-uranium particles. As summarized in Chapter 3, toxicologic studies have demonstrated that some health effects can occur in uranium-exposed animal models. Therefore, the committeeâs primary interest in uranium exposure is based on its action as an internal toxicant. Characterization of exposure to depleted uranium should include both radio- logic and chemical exposures, since the radiologic and chemical properties of depleted uranium could act synergistically to cause adverse health outcomes. External radiation exposure can be measured by a personal film badge, which can record exposure due to gamma rays, X-rays, and beta particles. Thermolumines- cent dosimeters are also used to record the cumulative exposure of workers over a predetermined period. External chemical exposure to uranium can be measured on the basis of airborne concentration. Such measurements can use stationary monitoring in workplaces or personal exposure monitoring. However, because the chemical toxicity of a uranium compound can be affected by its solubility, airborne uranium concentration is not commonly used in epidemiologic studies.
EXPOSURE ASSESSMENT 101 The internal dose resulting from exposure to uranium can be measured with biologic monitoring. Several methods are available for measuring uranium in biologic specimens (fluids, such as urine, and tissues, such as blood, hair, and nails). The methods include thermal ionization mass spectrometry (TIMS), instrumental neutron-activation analysis, delayed neutron counting, inductively coupled plasma-mass spectrometry (ICP-MS), inductively coupled plasma atomic-Âemission spectroscopy, a-spectroscopy, spectrophotometry, fluorometry, and kinetic phosphorescence analysis. Todorov et al. (2007) reviewed and com- pared those methods. Because of its accuracy, precision, high sample throughput, and ease of use, ICP-MS has become the preferred method for measuring ura- nium and depleted uranium in biologic samples (for example, Berard et al., 2003; Roth et al., 2003; Westphal et al., 2004; Ejnik et al., 2005; Parrish et al., 2006; Todorov et al., 2007). However, Horan et al. (2002) reported that TIMS has the âlowest detection limits of all current methodsâ and âis in the category of the best analytical method for uranium isotope determination in biological specimens.â Assessment of internal dose of uranium compounds is usually based on urinalysis (Ejnik et al., 2005), but hair and nail analysis can also be used (Karpas, 2001; Karpas et al., 2005). Whole-body radioactivity counting can detect small amounts of radioac- tive material (McDiarmid et al., 2000). However, it was not sensitive enough to detect depleted-uranium body burden in some depleted-uraniumâexposed soldiers (Toohey, 2003). Only 9 of 29 depleted-uraniumâexposed soldiers had detectable scores above the background level. The insensitivity of the method is due to the low radioactivity of depleted uranium and the tissue absorption of depleted-uranium radiation that was measured with a tissue-equivalent phantom containing known amounts of depleted uranium at different depths. Uranium is widely present in the natural environment. The general popula- tion can be exposed to a natural background level of uranium. The third National Report on Human Exposure to Environmental Chemicals (CDC, 2005) reported a geometric mean urinary uranium excretion of 9 ng/L in a sample of about 5,000 people across the United States; 95% of the population had concentrations below 46 ng/L. Studies of nonoccupationally exposed persons have shown uranium con- centrations in the general population of 11-22 ng/L (Dang et al., 1992; Medley et al., 1994; Ting et al., 1999). Urinary uranium concentrations of 1-41,800 ng/g of creatinine have been measured in soldiers and veterans where depleted uranium has been used (McDiarmid et al., 2006). A concentration of 1 ng/g of creatinine is equal to 1 ng/L of urine (Melissa McDiarmid, personal communication, June 28, 2007). Internal dose can be reconstructed from bioassay data by using a biokinetic model that predicts the time-dependent distribution and excretion of radionuclides deposited in the human body. A generic respiratory tract model can describe the deposition and retention of inhaled material in the respiratory tract and its clear- ance to blood or to the gastrointestinal tract. The Human Respiratory Tract Model
102 updated literature review of depleted uranium developed by the International Commission on Radiological Protection can pre- dict the behavior of inhaled radionuclides in the respiratory tract (ICRP, 2002). In the case of uranium, one of three generic absorption types can be applied for the chemical and physical form of the inhaled element. That approach may be unreliable because the assumption of different absorption rates can cause errors in the estimation of internal dose. The upper-bound estimated lifetime (50-year) radiation dose to the depleted-uraniumâexposed soldier with the highest urinary uranium concentration was 0.06 Sv (Squibb et al., 2005). References ACS (American Cancer Society). 2008. Cancer facts and figures. Atlanta, GA: American Cancer Society. Berard, P., A. Montegue, F. Briot, and J. C. Harduin. 2003. Procoradâs international intercomparisons highlight the evolution of techniques used to determine uranium in urine. Radiation Protection Dosimetry 105(1-4):447-450. CDC (Centers for Disease Control and Prevention). 2005. Third national report on human exposure to environmental chemicals. Atlanta, GA: Department of Health and Human Services, Centers for Disease Control and Prevention. Dang, H. S., V. R. Pullat, and K. C. Pillai. 1992. Determining the normal concentration of uranium in urine and application of the data to its biokinetics. Health Physics 62(6):562-566. DOD (Department of Defense). 2000. Environmental exposure report: Depleted uranium in the Gulf (II). Washington, DC: Department of Defense. Ejnik, J. W., T. I. Todorov, F. G. Mullick, K. Squibb, M. A. McDiarmid, and J. A. Centeno. 2005. Ura- nium analysis in urine by inductively coupled plasma dynamic reaction cell mass spectrometry. Analytical and Bioanalytical Chemistry 382(1):73-79. FEMP (Federal Environmental Management Project). 1997. Technical basis for internal dosimetry at the Federal Environmental Management Project. Fernald, OH: FEMP Publication. Horan, P., L. Dietz, and A. Durakovic. 2002. The quantitative analysis of depleted uranium isotopes in British, Canadian, and U.S. Gulf War veterans. Military Medicine 167(8):620-627. ICRP (International Commission on Radiological Protection). 1974. Report of the task groups on reference man. Elmsford, NY: Pergamon Press. âââ. 2002. Supporting guidance 3. Guide for the practical application of the ICRP human respira- tory tract model. Oxford, UK: Pergamon Press. Karpas, Z. 2001. Uranium bioassayâbeyond urinalysis. Health Physics 81(4):460-463. Karpas, Z., A. Lorber, H. Sela, O. Paz-Tal, Y. Hagag, P. Kurttio, and L. Salonen. 2005. Measurement of the 234U/238U ratio by MC-ICPMS in drinking water, hair, nails, and urine as an indicator of uranium exposure source. Health Physics 89(4):315-321. Marshall, A. C. 2005. Analysis of uranium dispersal and health effects using a Gulf war case study. Government Reports Announcements and Index (23):212. McDiarmid, M. A., J. P. Keogh, F. J. Hooper, K. McPhaul, K. Squibb, R. Kane, R. DiPino, M. Kabat, B. Kaup, L. Anderson, D. Hoover, L. Brown, M. Hamilton, D. Jacobson-Kram, B. Burrows, and M. Walsh. 2000. Health effects of depleted uranium on exposed Gulf War veterans. Envi- ronmental Research 82(2):168-180. McDiarmid, M. A., S. M. Engelhardt, M. Oliver, P. Gucer, P. D. Wilson, R. Kane, M. Kabat, B. Kaup, L. Anderson, D. Hoover, L. Brown, R. J. Albertini, R. Gudi, D. Jacobson-Kram, C. D. Thorne, and K. S. Squibb. 2006. Biological monitoring and surveillance results of Gulf War I veterans exposed to depleted uranium. International Archives of Occupational and Environmental Health 79(1):11-21.
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