- U.S. veterans who were exposed to depleted uranium during
the 1991 Gulf War have continued to excrete the potentially harmful chemical
in their urine for years after their exposure, according to a new study
published in the journal Health Physics.
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- The study indicates that soldiers may absorb depleted
uranium particles through inhalation, ingestion, or wound contamination,
said Roberto Gwiazda, an environmental toxicologist at UC Santa Cruz and
lead author of the study.
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- Fine particles of depleted uranium are created when munitions
made with the material strike a target. The new study did not address the
health effects of exposure to depleted uranium, a subject of ongoing debate,
but focused on a technique for detecting past exposure.
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- Low concentrations of uranium in the urine are normal
due to ingestion of naturally occuring uranium in food and water. Depleted
uranium is a by- product of the enrichment process used to make nuclear
fuel, in which one isotope of uranium (235U) is extracted, leaving behind
material depleted in that isotope. Depleted uranium is still weakly radioactive
and, like other heavy metals, can be toxic in high doses. Because of its
high density and other properties, it has been used in armor-piercing ammunition
and in armor for fighting vehicles.
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- Gwiazda and Donald Smith, professor of environmental
toxicology, developed a sensitive analytical technique to detect depleted
uranium in urine samples. By measuring the relative abundances of different
isotopes of uranium in the urine samples, the researchers were able to
distinguish between natural and depleted uranium.
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- "This is the only unambiguous way to determine past
exposure and uptake of depleted uranium," Gwiazda said.
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- The analysis of samples from Gulf War veterans was performed
in collaboration with the Baltimore Veterans Affairs Depleted Uranium Follow-up
Program, which is assessing, treating, and monitoring veterans who may
have been exposed to depleted uranium during the war.
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- The researchers applied their technique to three different
groups of Gulf War veterans. The first group of soldiers had shrapnel in
their bodies as a result of "friendly fire" incidents in which
their tanks or armored vehicles were hit by munitions containing depleted
uranium. The second group consisted of soldiers who did not have shrapnel
in them but were involved in the friendly fire incidents to different degrees,
either because they were in the vehicles that were hit or because they
participated in recovery operations. The third group was a reference group
and consisted of soldiers who participated in the war but not in combat
operations.
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- As expected, the soldiers with embedded shrapnel had
high concentrations of uranium in their urine, and the isotope analysis
showed that it was depleted uranium, presumably being released into their
bodies from the shrapnel.
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- A more striking finding was the presence of depleted
uranium in the urine of a significant number of soldiers in the second
group, without embedded shrapnel but with potential exposure through inhalation,
ingestion, or wound contamination. The uranium concentrations detected
in this group were, on average, six times higher than in the reference
group, but were still within the normal range for the U.S. population.
Nevertheless, Gwiazda said, it was remarkable that the signature of depleted
uranium could still be detected so many years after the exposure.
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- "These samples were taken six to eight years later,"
he said. The Veterans Affairs (VA) monitoring program has not reported
any findings of clinically significant health effects related to exposure
to depleted uranium, even in the highly exposed soldiers with embedded
shrapnel.
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- Any health effects of exposure to depleted uranium may
not be detectable without studying a large number of exposed individuals.
The technique developed at UCSC could be used to screen a large number
of people to identify those with past exposure to depleted uranium.
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- In addition to possible health effects in soldiers exposed
during combat, concerns about depleted uranium include environmental contamination
of battlefield sites. Civilian populations may be exposed through contact
with depleted uranium fragments and dust left in the soil or with contaminated
military equipment left behind after a conflict.
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- "We don't know if that kind of exposure will have
any health effects. But now we have a technique that enables us to detect
past exposure to depleted uranium," Gwiazda said.
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- The paper was published in the January issue of Health
Physics. The authors include Katherine Squibb and Melissa McDiarmid of
the University of Maryland School of Medicine, in addition to Gwiazda and
Smith.
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- http://www.sciencedaily.com/releases/2004/01/040122090433.htm
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