Environmental Health Perspectives • volume 117 | number 6 | June 2009
Responding to veterans’ concerns and as part
of an ongoing medical surveillance program
for U.S. military veterans exposed to depleted
uranium (DU), biological monitoring of urine
uranium (U) concentrations has been carried
out by the Department of Veterans Affairs
(VA) since the early 1990s. Since the first
Gulf War in 1991, DU has been used both in
armor-piercing projectiles and as armor itself,
because of its high density, availability, and
relative low cost [Army Environmental Policy
Institute (AEPI) 1995].
A by-product of the U enrichment process,
DU is the material remaining after the more
radioactive U234 and U235 isotopes are removed
from natural uranium (Unat) (AEPI 1995). DU
thus possesses only about 60% of the radioac-
tivity of Unat but retains the elemental, chemi-
cal characteristics of this heavy metal.
Although DU was first deployed in the
Gulf War in 1991 and was also used in the
Bosnian conflicts, it has played less of a role
in the present military campaigns in Iraq and
Afghanistan. Despite this, health concerns
persist about potential exposure risks, so sur-
veillance efforts have been expanded to offer
biomonitoring to any veteran requesting a
test for DU exposure.
Veterans access the biomonitoring pro-
gram through any VA clinic or hospital.
The U.S. Navy and Air Force also use the
VA’s DU biomonitoring program for their
active-duty service members. The assessment
includes a self-completed questionnaire and
submission of a 24-hr urine sample, which
is analyzed for total U concentration and for
the presence of DU. With accompanying
interpretation, results are returned to the vet-
eran and his or her health care provider. The
questionnaire addresses specific DU exposure
scenarios of concern to veterans. Examples
of potential exposure opportunities include
inhalation of smoke containing DU particles
(e.g., during a fire involving DU weapons at
Doha depot, Qatar), entering or salvaging
vehicles or bunkers hit by DU projectiles, and
reporting close contact with DU munitions
in tanks and other vehicles.
Results of surveillance completed between
August 1998 and December 1999 and
between January 2000 and December 2002
have been previously reported (McDiarmid
et al. 2001a, 2004a). Both studies concluded
that a veteran without a history of traumatic
injury involving DU munitions would be
unlikely to have an elevated urine U value.
In the 5 years since the last report of these
surveillance results, 1,769 additional urine
samples have been measured. In addition, we
can now accurately perform determinations of
U isotopic signatures at very low total U con-
centrations, enabling accurate identification
of DU as opposed to Unat. This capability has
significantly enhanced our ability to assess
DU exposure. We report here an update of
Materials and Methods
Program enrollment. From January 2003
through June 2008, 1,769 veterans and active-
duty service members from the U.S. Navy
and Air Force who served in the 1991 Gulf
War and/or who have served since the end of
the Gulf War (referred to as post-Gulf War
veterans) provided 24-hr urine samples for
U testing. The latter group includes veterans
of the military conflicts in Iraq, Afghanistan,
and the Balkans. The veterans’ local VA or the
service members’ medical treatment facility
contacted the DU program at the Baltimore
VA Medical Center (BVAMC) to request
a test kit and coordinated collection of the
urine sample. As previously reported, the kit
contained a demographic and exposure ques-
tionnaire, instructions for the collection and
handling of the 24-hr urine specimen, and
urine collection containers (McDiarmid et al.
2001a, 2004a). The collected specimen was
returned to the BVAMC for processing. This
protocol has been reviewed and approved
by the University of Maryland School of
Medicine Institutional Review Board and
the Research and Development Office at the
BVAMC. Personnel at the local VA hospital,
clinic, or medical treatment facility obtained
consent for medical evaluation. Informed
consent requirements for the purposes of
population surveillance were waived after
review by the University of Maryland School
of Medicine Institutional Review Board.
Urine U analytic methods. Measurements
of total volume and creatinine in the 24-hr
urine samples were made at the BVAMC
clinical labs. Before July 2003, U concen-
trations for Gulf War veterans were mea-
sured by STL Richland (formerly Quanterra,
Inc., and International Technology Analytic
Services; Richland, WA) using kinetic phos-
phorescence analysis (KPA). When urine U
concentrations were > 0.05 µg U/g creati-
nine, patients were asked to submit a second
Address correspondence to K. S. Squibb, 405 W.
Redwood St., 2nd Floor, Baltimore, MD 21201
USA. Telephone: (410) 706-7464. Fax: (410) 706-
4078. E-mail: email@example.com
We thank the Depleted Uranium Follow-up
Program administrative staff and the Baltimore
Veterans Administration Clinical Labs for their
This program is funded through the U.S.
Department of Veterans Affairs.
The authors declare they have no competing
Received 20 November 2008; accepted 25 February
Biological Monitoring for Depleted Uranium Exposure in U.S. Veterans
Carrie D. Dorsey,1,2 Susan M. Engelhardt,2 Katherine S. Squibb,2,3 and Melissa A. McDiarmid1,2
1Department of Medicine, University of Maryland School of Medicine, Baltimore, Maryland, USA; 2Veterans Affairs Medical Center,
Baltimore, Maryland, USA; 3Department of Epidemiology and Preventive Medicine, University of Maryland School of Medicine,
Baltimore, Maryland, USA
Background: As part of an ongoing medical surveillance program for U.S. veterans exposed to
depleted uranium (DU), biological monitoring of urine uranium (U) concentrations is offered to
any veteran of the Gulf War and those serving in more recent conflicts (post-Gulf War veterans).
oBjectives: Since a previous report of surveillance findings in 2004, an improved methodology
for determination of the isotopic ratio of U in urine (235U:238U) has been developed and allows for
more definitive evaluation of DU exposure. This report updates previous findings.
Methods: Veterans provide a 24-hr urine specimen and complete a DU exposure questionnaire.
Specimens are sent to the Baltimore Veterans Affairs Medical Center for processing. Uranium
concentration and isotopic ratio are measured using ICP-MS at the Armed Forces Institute of
results: Between January 2003 and June 2008, we received 1,769 urine specimens for U analysis.
The mean urine U measure was 0.009 µg U/g creatinine. Mean urine U concentrations for Gulf
War and post-Gulf War veterans were 0.008 and 0.009 µg U/g creatinine, respectively. Only 3 of
the 1,700 (0.01%) specimens for which we completed isotopic determination showed evidence of
DU. Exposure histories confirmed that these three individuals had been involved in “friendly fire”
incidents involving DU munitions or armored vehicles.
conclusions: No urine U measure with a “depleted” isotopic signature has been detected in U.S.
veterans without a history of retained DU embedded fragments from previous injury. These find-
ings suggest that future DU-related health harm is unlikely in veterans without DU fragments.
key words: bioassay, biomonitoring, depleted uranium, exposure, isotopic analysis. Environ
Health Perspect 117:953–956 (2009). doi:10.1289/ehp.0800413 available via http://dx.doi.org/
[Online 25 February 2009]