Depleted Uranium (header image)

Image of Davy Crockett Weapon System


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This website is sponsored by the U.S. Army Garrison-Hawaii as a means of making information that the Army knows about Depleted Uranium on our training ranges in Hawaii readily available to the public. We hope the information contained herein will help address the public's questions and concerns about DU. The information provided is a compilation of data from the Department of Defense Health Affairs, Center for Disease Control, Agency for Toxic Substances and Disease Registry, Office of Public Health and Environmental Hazards, and Department of Veterans Affairs.



Hawaii has played a vital role in our national defense since 1913.  During World War II, the military conducted extensive training to prepare our Nation's forces for combat and to protect Hawaii from outside attacks.  This role continues today.  Key to meeting this national defense role has been the military's conduct of live-fire training and testing with military munitions.  Between 1960 and 1968, the military used the M101 spotting round in training.  The M101 was a small (about 8 inches in length and 1-inch diameter) low speed projectile weighing about one pound and containing about 6.7 ounces of depleted uranium (DU) alloy.  Unlike modern DU kinetic penetrators that are designed to defeat armor and may generate a cloud of DU dust upon impact, the M101 spotting round was used to identify the flight path of the Davy Crockett warhead.  Use of the M101 would have deposited DU in large fragments.

In August 2005, while conducting range clearance activities to modernize ranges at Schofield Barracks, an Army contractor discovered 15 tail assemblies from the M101 spotting round, a component of the Davy Crockett weapon system.

By early 2006, a scoping survey confirmed the presence of DU fragments from the M101 on a portion of Schofield Barracks’ impact area.  After confirming the presence of DU, the Army disclosed that information to the public. 

The Davy Crockett was the name given to the M28 and M29 series of recoilless guns.  This weapon system was produced from 1960 until 1968 and was used in training until 1968.  Although the Davy Crockett could use several types of munitions, the munition of interest is the M101 spotting round that contained depleted uranium (DU).  Unlike modern munitions that use DU penetrators to defeat enemy armor, the DU in the M101 was used to provide weight sufficient for the spotting round to mimic the trajectory of the Davy Crockett’s nuclear warhead.  The M101 was a small (about 8 inches in length and 1-inch diameter), low- speed projectile that contained 6.7 ounces of a DU-alloy.

When the Davy Crockett was used, it was a classified weapon system and information concerning its deployment to Schofield and associated training activities was closely guarded.  

Some speculate that DU used in penetrators is linked to Gulf War illnesses; however, medical screening and tests do not support this speculation.  Studies concerning the health effects of DU can be found the Information Resources page. 

The Army is committed to transparency on environmental issues and will provide information it discovers about the presence of DU on its ranges in Hawaii to the State of Hawaii, Department of Health, federal regulators and the public as it becomes available.


Depleted Uranium

DU is a processed form of uranium.  Uranium is a weakly radioactive heavy metal that occurs naturally in the environment.  Rocks, soil, surface, water, air, plants, and animals all contain varying amounts of uranium.  Because it is found everywhere on earth, we eat, drink and breathe a small amount every day.  People have been mining uranium and using it in various applications for over 60 years, so there is a great deal of information available on uranium.

DU is the uranium left over from the process that enriches uranium for commercial and military uses.  Enrichment is a process where a portion of the most radioactive forms of uranium are removed from naturally occurring uranium.  DU is nearly twice as dense as lead, with 40% less radioactivity than natural uranium.

Under certain circumstances and at very high temperatures, DU can aerosolize.  Research by military and non-military agencies confirm that this does not occur during brush fires.  Re-suspension is primarily due to particle size rather than particle density or chemical form. We believe that the primary reason for immobilization is due to the large    particle size of the uranium and the fact that the     uranium primarily exists as large metal fragments.  Among other factors, the soil types on Hawaii’s ranges also serve to limit DU migration from the impact area.  Although it is highly unlikely that DU will move off the impact area due to military live-fire training, air monitoring and sampling will be conducted to ensure that migration is not occurring.


What is DU Used For?

DU is currently used in commercial and military applications that require the use of a very dense material.  Commercial applications include:    ballast and counterweights in airplanes and ships, radiation shielding and collimation in medicine, radiation therapy and industry. 

DU is currently used by the armed forces as armor to protect Army tanks, and as penetrators in military munitions to destroy enemy armored vehicles.

DU’s ability to protect our Soldiers is unsurpassed.  First, DU provides protection for the Abrams tank and its crew against enemy anti-tank munitions.  DU armor is designed to cause rounds to function prematurely or bounce off the exterior of a tank.  Second, when used in armor-piercing projectiles, DU provides unmatched capability to engage and penetrate enemy armor at distances out of the range of the enemy’s weapons systems.


Should I Be Concerned?

No.  There is no imminent or immediate threat to human health from the DU present on Hawaii’s ranges, and the Army is working in concert with state and federal agencies to thoroughly assess the risk and determine the actions required to address the DU present on Hawaii’s ranges.

The Army takes very seriously all issues and public concerns arising from DU.  The community’s health and safety, on post and off, is the top priority.  As such, the Army is taking appropriate, proactive measures to assess the overall situation and to develop a comprehensive, transparent, full-disclosure strategy.  This principled approach relies on federal and international scientific methods and protocols in consultation with state and federal officials who are responsible for ensuring public health and safety.

Based on data gathered and careful analysis of the current situation, there is no immediate or imminent health risk to people who work at Schofield Barracks or Pohakuloa Training Area (PTA) or live in communities adjacent to these military facilities from the DU present in the impact areas.  A comprehensive risk assessment will be completed in 2008.

Any DU residue present is limited to impact areas well within the perimeter of operational ranges.  These areas are not publicly accessible.  Very few range and safety personnel access the impact areas of our operational ranges.  Those people that work in these areas are trained to recognize potential hazards associated with military munitions.

The migration of DU off the military installation is highly unlikely.  Studies have shown that DU transport is limited and that it is unlikely to move from the range under most conditions.  Studies also have shown that the DU fragment size and the environmental conditions at the ranges in Hawaii serve to minimize the potential for migration, including by air.  The Army will, however, monitor these ranges to determine whether migration occurs.  The results of the monitoring efforts will be provided to the state and federal agency partners for review.

Studies conducted by numerous non-military agencies, including the World Health Organization and the Department of Health and Human Services, have not found credible evidence linking DU to radiation-induced illnesses.  These studies can be found on the Information Resources page.

The Army has been working closely with the Nuclear Regulatory Commission (NRC) to address the presence of DU on Hawaii's ranges.  The NRC is also involved in review and oversight of the survey process.  If appropriate, the NRC will license  ranges for long-term environmental monitoring or clean up.

The State of Hawaii Department of Health and Department of Defense are collaborating on this process.  Additionally, the Army is in constant communication and coordination with a wide array of DOD and non-DOD federal agencies.  Together we will plan the “way-ahead” to address the DU present on Schofield Barracks and PTA.  The organizations and some of the individuals involved in this effort are identified on the Partners page. 

The Army's two-month survey at Schofield Barracks and PTA covered more than 425 acres. More than 1,400 air, vegetation, and soil samples were collected and sent to independent labs on the mainland for testing and analysis. The results of the Schofield Barracks Human Health Risk Assessment are available here. The results of the PTA Human Health Risk Assessment are available here.


Current Response Initiatives

M101 tail assemblies that were found at Schofield Barracks were removed and properly disposed of following Department of Transportation and NRC requirements.  The Army, in coordination with the state and federal agencies, has completed a comprehensive survey of Schofield Barracks' range and defined the areas where DU is present.  It has also, based on a preliminary survey and an archival research, defines all the areas at PTA where the M101 is believed to have been used.  The Army is working with the NRC in close coordination with the state of Hawaii’s Department of Health to obtain the NRC license required given the presence of DU on its ranges.

The Army conducted air and water sampling at Schofield Barracks to determine if DU is migrating off the range.  The sampling to date does not indicate the presence of DU in air or water samples.  The Army will continue this sampling for the foreseeable future. 

At the direction of Mr. Tad Davis, Deputy Assistant Secretary of the Army for Environment, Safety, and Occupational Health, the Army initiated the following four-point plan to assure transparency:

  • All information obtained will be provided in a timely manner to the Hawaii State Department of Health.

  • The state will be a partner in the planning and execution of a survey and monitoring efforts to address Schofield Barracks, Makua Military Reservation, and PTA.

  • The state will be a partner in the planning and execution of mutually agreed upon response actions.

  • The Army will provide any necessary training to state participants.

The Army is committed to providing information on the Hawaii DU efforts to the public.  This website is an important step in providing the public a readily accessible source for information.


For more information contact:


- U.S. Army Garrison-Hawaii Public Affairs, (808)656-3154

Hawaii Island
- U.S. Army Garrison-Pohakuloa Public Affairs, (808)969-2411



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