I. OVERVIEW^[1]

Figure 1. Abrams Tank and DU Sabot Rounds

The Gulf War was the arena for the first battlefield use of armor-piercing munitions and reinforced tank armor incorporating depleted uranium (DU). This very dense metal is a by-product of the process by which natural uranium is "enriched" with the addition of radioactive isotopes taken from other uranium. The leftover uranium, drained of 40% of its original radioactivity, is called "depleted uranium," or DU.

Figure 2. DU Round Discarding Its Sabot

Depleted uranium played a key role in the overwhelming success of US forces during the Gulf War. Machined into armor-piercing 120mm DU ‘sabot’ rounds (Figures 1 and 2), DU penetrators were called "silver bullets" by tankers, who quickly recognized the tremendous lethal advantage these rounds provided against enemy tanks. The extreme density of the metal and its self-sharpening properties make DU a formidable weapon; its projectiles slice through thicker, tougher armor at greater ranges than other high-velocity rounds. In addition, DU is pyrophoric—upon striking armor, small particles break off and combust spontaneously in air, often touching off explosions of fuel and munitions.

DU was also used to enhance the armor protection of US tanks. In one noteworthy incident, an M1A1 Abrams Main Battle Tank, its thick steel armor reinforced by a sandwiched layer of DU, rebuffed a close-in attack by three Iraqi T-72 tanks. After deflecting three hits from the Iraqi tanks, the Abrams’ crew dispatched the T-72s with a single DU round to each (an expanded version of the encounter can be found in Tab F). Similarly, Air Force A-10 "tank-busters" and Marine Corps Harrier close air support aircraft fired 30mm and 25mm DU rounds, respectively, with deadly effect against Iraqi armor (see Tab F for a description of DU use in the Gulf).

During the Gulf War, DU helped US forces fight more effectively and defend themselves more confidently. American tankers and A-10 pilots destroyed thousands of Iraqi combat vehicles without the loss of a single US tank to enemy fire. Since the Gulf War, DU’s battlefield effectiveness has encouraged its steady proliferation into the arsenals of allies and adversaries alike. There is little doubt, therefore, that DU will be used against our troops in some future conflict.

Figure 3. M1A1 in the Gulf

While DU’s combat debut showed the metal’s clear superiority for both armor penetration and armor protection, its chemical toxicity—common to all forms of uranium and similar to other heavy metals—and its low-level radiological properties gave rise to concerns about possible combat and non-combat health risks associated with DU use. The issues to be addressed in this report are: did DU pose an unacceptable health risk to American troops; were personnel trained to recognize and communicate that risk; and were troops, once exposed to DU, adequately monitored and treated?

To many veterans and members of the public, the term "exposure," especially when associated with the word "radiation," signifies that adverse health effects will follow. In fact, exposure in the present case is used to describe events and situations where soldiers came into contact with depleted uranium fragments and particles formed when DU struck armor targets or "slow cooked" in fires. "Exposure" in the current context is better understood if equated with most people’s daily "exposure" to automobile exhaust, second-hand smoke, or similar noxious or potentially toxic substances. In minute quantities, such exposures will not produce harmful effects; however, when certain thresholds are exceeded, adverse health effects might result.

This report examines a variety of exposures that occurred during and after the Gulf War. The report begins with a short, but important lesson on DU—what it is and the potential health risks of its chemical and radiological properties (see II. Depleted Uranium—A Short Course). The report then describes DU exposures that occurred during the Gulf War, and relates those exposures to possible health effects (see III. Assessment Of Potential Health Effects From DU Use In The Gulf Theater, 1990-1991). Next, the report addresses recent environmental studies of various DU munitions, environmental assessments of DU contamination on the battlefield, results of current medical studies, future monitoring efforts, and on-going and planned research (see IV. Follow-Up). After the Follow-up, the report presents some lessons learned since the Gulf War (see V. Lessons Learned), addressing pre-Gulf War training shortfalls, and recommending steps DoD can take to better prepare troops to operate in environments where they might encounter DU contamination. The Conclusion (see VI. Conclusion) summarizes the contents of the report, describes ongoing research and medical follow-up programs, and relates key findings and conclusions based on evidence analyzed to date.

This investigation, and medical and scientific research to date, have not established any relationship between DU exposures and the undiagnosed illnesses presented by some Gulf War veterans. These efforts are ongoing, and this office will continue to apply lessons learned from the investigation and research efforts to safeguard the health of our troops.

Investigators from the Office of the Special Assistant have interviewed hundreds of Gulf War combatants and eyewitnesses, reconstructed numerous operations, consulted with subject matter experts, and researched the most current body of knowledge regarding DU’s medical effects and environmental impact. The investigation classifies possible DU exposures into three Levels, encompassing 13 separate activities, shown in Table 1. These Levels are based on initial estimates about the extent of the exposures. For each Level, Table 1 provides a description of the activity, a current estimate of the number of soldiers involved, the duration of the exposure, and the personal protective equipment used, if any.

Table 1. Incident Summary

The investigation includes incidents in which US tanks mistakenly fired DU armor-piercing rounds into other US combat vehicles, exposing surviving crewmen in those vehicles to wounds from DU fragments and/or inhalation and ingestion of particles formed when DU munitions penetrate armor, especially tank armor. During these "friendly fire" incidents, personnel rushing to evacuate and rescue fellow troops from stricken vehicles may have also been directly exposed to DU. These immediate and direct exposures are part of Level I exposures (see Tab G).

A second, lower level of exposures to DU occurred after combat as explosive ordnance disposal (EOD) personnel entered DU-contaminated vehicles to remove unexploded munitions. In addition to EOD personnel, battle damage assessment teams (BDAT), radiation control (RADCON) teams, and salvage crews worked in and on the damaged or destroyed vehicles as they were processed for repair or disposal. Also classified with this group would be personnel involved in cleanup and recovery operations in the North Compound of Camp Doha, Kuwait, following the motor pool fire in which DU munitions detonated and burned. These personnel, and others who may have come into direct contact with the dust-like residue of expended DU rounds, are categorized under the Level II exposure category (see Tab G).

A third category of DU exposure, Level III, also discussed in Tab G, defines personnel whose exposure to DU was short-term and generally very low. These exposures may have occurred as personnel passed through and inhaled smoke from burning DU, casually handled spent DU penetrators, or briefly entered DU-contaminated vehicles on the battlefield or in salvage yards.

These three exposure categories are not exclusive. Given the complexity of combat operations during the Gulf War and the wide variety of post-combat assignments, there are other possible DU exposure scenarios which could overlap categories. The purpose of this report is to relate the documented incidents during which exposure to DU was a distinct possibility, and to discuss what is currently known about the potential health effects resulting from those exposures.

Dose and toxicity determine health effects. The US Army Center for Health Promotion and Preventive Medicine (CHPPM) is concentrating on determining possible DU intakes by Level I soldiers, who were most exposed. Initial estimates represent an upper bound to exposure, commonly called the "worst case," based on the limited available test data for DU sabot rounds which penetrated DU armor. In this report, "worst case" refers to conditions that are thought to produce a maximum exposure to DU. These estimates indicate that the radiological risk for these events is well within current regulatory limits for industrial workers. It should be cautioned that these dose estimates are very preliminary, requiring additional testing to fill data gaps, require further refinement of dose estimates, and will be influenced by current research about DU’s medical effects.

Since 1993, the Department of Veterans Affairs has been monitoring 33 vets who were seriously injured in friendly fire incidents involving depleted uranium. These veterans are being monitored at the Baltimore VA Medical Center. While these veterans have very definite medical afflictions resulting from their wartime injuries, they are not sick from the heavy metal or radiological toxicity of DU. About half of this group still have depleted uranium metal fragments in their bodies. Those with higher than normal levels of uranium in their urine since monitoring began in 1993 have embedded DU fragments. These veterans are being followed very carefully and a number of different medical tests are being done to determine if the depleted uranium fragments are causing any health problems. The veterans being followed who were in friendly fire incidents but who do not have retained depleted uranium fragments, generally speaking, have not shown higher than normal levels of uranium in their urine. For the 33 veterans in the program, tests for kidney function have all been normal. In addition, the reproductive health of this group appears to be normal in that all babies fathered by these veterans between 1991 and 1997 had no observable birth defects.

The DoD and Department of Veterans Affairs recently instituted a new medical follow-up program to evaluate all individuals who were in or on vehicles that were struck by friendly fire, as well as those who worked around DU-contaminated vehicles. These individuals were less exposed than the 33 in the original program, but potentially more exposed than the general military population. While their DU exposures are unlikely to have exceeded the threshold levels at which health effects might be observed, prudence dictates that they be evaluated to establish any residual body burden of DU. Veterans whose known exposures caused them to be classified as Level I or Level II exposure participants who worked on DU-contaminated vehicles(described further in Tab G) will be notified of their exposures and offered a medical evaluation. They will also receive the letter and DU information shown in Tab K, DU Notification and Medical Follow-up.

To illustrate specific examples of DU exposures that occurred during the war, this report draws upon several incidents during which US military personnel were exposed or potentially exposed to DU through inhalation, ingestion, wound or bare skin contact. Where the essential facts have been established, those incidents have been investigated and are reported here. Where the reports of DU exposure are incomplete or remain unsubstantiated, the investigation continues.

Based on data developed to date, the Office of the Special Assistant believes that while DU can pose a chemical toxicity and radiological hazard under specific conditions, the available evidence does not support claims that DU caused or is causing the undiagnosed illnesses some Gulf War veterans are experiencing.

Methodology

The Office of the Special Assistant’s investigation of DU as a potential cause of Gulf War illnesses adopted a health risk assessment methodology patterned on that used by the US Environmental Protection Agency. This process, outlined in Tab D, estimates the health risk from contaminant concentrations, site exposure, and contaminant toxicity characteristics. It consists of four steps: Hazard Identification, Toxicity Assessment, Dose Assessment, and Risk Characterization, defined below:

• Hazard Identification - who was exposed, and how? Which incidents warrant a full investigation?
• Toxicity Assessment - what are the known medical effects of human exposure to DU? At what levels of exposure do these effects occur? How can the effects be mitigated?
• Dose Assessment - how much DU were the troops exposed to? What chemical or radiological doses do these intakes represent?
• Risk Characterization - using validated toxicity and dose information, what medical effects can be anticipated? How serious are those effects? How can the effects be communicated to those affected?

Performing this assessment for DU involves the cooperative efforts of several organizations, specifically;

• The Office of the Special Assistant for Gulf War Illnesses - Hazard Identification and Risk Characterization.
• RAND Corporation - Toxicity Assessment.
• US Army Center for Health Promotion and Preventive Medicine (CHPPM) - Dose Assessment (Exposure and Risk Assessment).
• VA DU medical surveillance program – communication with those affected.

As described above, the Office of the Special Assistant for Gulf War Illnesses has focused its investigation on determining what happened, what exposures may have occurred, and who may have been exposed. Exposures have been subdivided into levels and scenarios so they can be related to toxicity and dose information.

With a view toward developing a toxicity assessment, the RAND Corporation is conducting an independent review of available medical and scientific literature on DU’s known medical and health effects. RAND’s review focuses on the health effects of internalized depleted uranium and discusses the levels of external exposure.

CHPPM is performing the exposure and risk assessment by estimating the amount of DU which may have been taken into the body for each of the 13 exposure groups. Since direct measurements of the radiation and chemical doses were not taken at the time the incidents occurred, CHPPM is using the best available data, combined with scientific and engineering principles, to develop its exposure and risk assessments. Specific CHPPM activities include:

• Reviewing test data on the behavior of DU during fires and impacts with armor;
• Evaluating the usefulness and appropriateness of that data in modeling the amount of DU a soldier might take in through inhalation, ingestion, or wound contamination;
• Identifying data gaps; and
• Performing estimates of the radiological and chemical doses for each of the 13 activities involving possible DU exposure.

Finally, the Office of the Special Assistant will combine the results of CHPPM’s dose assessments and RAND’s medical review to characterize the risks to health, and to develop clear, concise discussions of those risks for each of the 13 exposure scenarios and events. That work is currently in progress.

The final, comprehensive report on DU’s potential role in Gulf War illnesses, combining all these studies and the screening results from the DoD-VA expanded medical follow-up, is expected in approximately one year.

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