Depleted Uranium and Health: Facts and Helpful
by Glen Lawrence
Department of Chemistry and Biochemistry, Long Island University,
Brooklyn, NY 11201
A significant development in ballistics has been the
DU (depleted uranium) kinetic energy penetrator. It is able to pierce
armor, including DU armor that can withstand conventional shelling,
and as it slices through hard materials, it heats up and ignites.
Burning at high temperatures, it often completely destroys its target,
whether an armored tank, a concrete bunker or conventional vehicle.
As the nearly pure uranium metal in the penetrator burns, it sends
up smoke containing fine particles of uranium oxide aerosol. The smoke
particles are extremely small and can be easily inhaled without realizing;
most are about 1 micron in diameter (1/1000 of a millimeter), which
is not even visible to the naked eye .
What are uranium oxides and are they dangerous?
There are 3 major uranium oxides produced by burning,
these are UO3, U3O8 and UO2,
known as uranium trioxide, triuranium octoxide and uranium dioxide,
with the latter two predominating. Although uranium is one of the
densest metals known, the oxides in the smoke and dust are not so
dense and remain suspended in the air for a long time. In fact, particles
of DU oxides were detected more than ten miles from a National Lead
DU munitions plant in Colonie, NY years ago, causing the State of
New York to shut down the plant for excessive release of radioactive
materials into the environment . Uranium, in any form, is considered
to be a chemical poison as well as a radiation hazard if taken internally,
although moderate in comparison to other chemical poisons and radiation
These oxides dissolve in water (and body fluids) at
very different rates. UO3 dissolves relatively quickly
(hours to days), whereas U3O8 dissolves more
slowly (weeks to months) and UO2 dissolves very slowly
(months or years) . The rate at which they dissolve depends very
much on the size of the particles and the properties of the solvent.
Very small particles of UO2 (<0.01 micron) seem to dissolve
relatively fast and are absorbed from lung as quickly as soluble uranium
compounds . Particles of either UO2 or U3O8
with average diameter of 0.5 microns cause much greater lung damage
in animals than particles with average diameter of 2.3 microns or
larger [5,6]. Larger particles tend to get removed from the lungs
in phlegm. There was much greater retention of the uranium in the
lungs with the smaller particles, as well as greater kidney damage,
indicating more absorption of the uranium into the blood. There have
been numerous studies of the effects of inhaled uranium oxide particles
on lab animals with their toxicity ranging from negligible to severe.
The toxicity depends on many factors, including not only size of the
particles, but how the particles were prepared, how they are administered
(dry or in a liquid) and many other factors .
The effect that DU shells have on their targets lures
the curious to see what destruction it can do. Just walking or rummaging
around a DU destroyed vehicle long after the dust has settled can
resuspend the fine particles of uranium oxide, which may be inhaled
or cling to skin and clothing. Inhaling a mixture of the uranium oxides
with a wide range of particle sizes in the smoke and dust coming from
burning DU penetrators or resuspended dust works like a time release
capsule, with the uranium oxides dissolving at different rates and
entering the bloodstream over a prolonged time.
How toxic is uranium?
There is continuing debate about how toxic uranium
really is. Uranium is not absorbed from the digestive tract very well.
Less than 2 percent of uranium oxides taken in by mouth get absorbed
and enter the blood, with the bulk of it passing through in the feces
. Uranium also doesn't exert its toxic effects immediately like
cyanide or strychnine, but instead can take several days, so it may
not be noticed for more than a day that poisoning has occurred. An
acute nonlethal dose of uranium causes kidney damage within two weeks,
which is somewhat reversible, with restoration of most kidney function
after several months .
Several studies have been done to determine whether
high levels of uranium in drinking water have any ill health effects.
People drinking well water with high levels of uranium generally don't
show any chronic illness, but urinalysis indicates that higher levels
of uranium in drinking water results in increased indicators for kidney
damage [10-12]. The correlation seems to be linear and indicates that
any increase in uranium exposure would result in an increase in the
degree of kidney damage, even if it is not sufficient to cause acute
toxic effects. It has also been found that exposure to moderate levels
of uranium for some time makes the kidney more resistant to a subsequent
toxic dose. Perhaps the kidney problems that appear to occur when
people are exposed to high levels of uranium for the first time, will
gradually return to normal once they are removed from the source of
contamination, although it is not possible to say whether recovery
would be 100 percent.
What is the most likely way to get toxic exposure
The inhalation of DU dust is the most likely route
for uranium to enter the body and do serious damage, with the smallest,
invisible DU dust particles doing the greatest damage. Consequently,
you may not realize that you are even getting inhalation exposure.
As these dust particles slowly dissolve in the lungs and the uranium
is absorbed into the blood, it gets distributed to all parts of the
body [13,14]. Most health professionals looking for uranium poisoning
will focus on the kidney because that organ is the most vulnerable
and kidney malfunction can be easily diagnosed by analyzing urine
for specific clinical parameters, such as alkaline phosphatase or
beta-microglobulin. However, when constant low doses of uranium are
being absorbed, as they would be from DU dust particles in the lungs,
it gets distributed to bone, brain, liver, lymph, spleen, testes and
other organs. Once deposited in these tissues, there are several things
that can happen.
What health effects result from exposure to uranium
Uranium dust may do permanent damage to the lungs
resulting in chronic respiratory problems [15,16]. Uranium exposure
also affects neurological function. Rats exposed to uranium had impaired
nerve cell function [17, 18] and 1991 Gulf War veterans who were excreting
high levels of uranium in their urine showed some impairment in cognitive
function . Uranium exposure can have a wide range of health effects
that may also include skin rashes, headaches, blurred vision, sensitivity
to light and sound, localized numbness and urinary symptoms, such
as kidney stones, increased urine volume and blood in the urine.
Researchers at the Armed Forces Radiobiology Research
Institute (AFRRI) in Bethesda, MD and others have found that uranium
causes mutations in DNA [20, 21] and uranium exposure can result in
increased chromosomal aberrations [22-26]. It is a widely accepted
principle in molecular biology that agents that cause mutations or
damage DNA can cause cancer. Mutations in the DNA of germ cells (in
the testes and ovaries) may lead to birth defects or miscarriage.
It is plausible that uranium exposure in a man could lead to increased
risk of birth defects in his children conceived after the exposure
Does exposure to uranium cause people to get cancer?
Studies at the Armed Forces Radiobiology Research
Institute showed that human cells grown in culture dishes could be
transformed into cancerous cells when exposed to uranium . Researchers
in Albuquerque, NM implanted DU metal into the muscle of rats (a model
for shrapnel wounds), causing 18% to develop sarcomas (cancerous tumors
around the implant site) . Epidemiologic studies found modest
increases in certain types of cancers in uranium workers, including
cancers of the lung, lymph nodes, kidney and brain [30-33].
The uranium processing and milling industries had
stringent safeguards built in when they were developing because uranium
was known to be toxic. Workers were closely monitored with radiation
badges and frequent urine tests, and if exposed to too much radiation,
were removed from the high exposure risk areas until their exposure
level dropped below the acceptable limits for a given time period.
Consequently, the increased risk of cancers in this industry is not
large, but is significant. The latency period, or time between exposure
to a carcinogen and development of cancer can be many years (often
5 to 20 or more years for heavy metal carcinogens).
What are practical protective measures for exposed
During the Manhattan Project to develop the atomic
bomb in the early 1940s, many scientists investigated the toxic properties
of uranium. They found that uranium oxides stick very well to cotton
cloth, but did not wash out with soap or laundry detergent . The
uranium would wash out with a 2% solution of sodium bicarbonate (baking
soda). Clothing can become contaminated with DU dust and normal laundering
will not remove it. Those at risk of DU dust exposure should have
their clothing washed with baking soda (about 6 ounces of baking soda
in 2 gallons of water).
Other studies done in the 1940s found that some uranium
compounds could be absorbed through the skin (of lab animals) .
More recent studies done in the late 1980s and 1990s found that even
relatively insoluble uranium oxide could damage skin cells when applied
daily for a month, resulting in the skin becoming thinner and more
permeable . If the uranium oxides dissolve, they are more easily
absorbed [36, 37], and certain oils and lotions may cause the uranium
to be absorbed through the skin more quickly. Some uranium oxides
can dissolve in sweat, making it easier for them to be absorbed. If
clothing is highly contaminated with DU dust, and if it remains in
contact with sweaty skin for long periods of time, there could be
significant amounts dissolved and absorbed through the skin. Therefore,
it is important to get the clothing clean and free of uranium contamination.
Is there any antidote if uranium exposure is suspected?
It was found that giving animals sodium citrate protected
them from an otherwise lethal toxic dose of uranium [38-40]. Sodium
citrate is a neutralized form of citric acid. The sodium citrate caused
the animals to excrete uranium faster, resulting in less uranium being
deposited in the body. Would this help to protect people who have
had toxic exposure to uranium? It was not tested in humans, but it
would probably offer some protection. Citric acid is a natural component
of citrus fruits and juices. The food industry adds citric acid and
sodium citrate to many different foods, especially beverages, although
citrus fruits and juices provide the greatest amount of citric acid
or citrate. Carbonated sodas have very little citric acid. If one
suspects or anticipates DU exposure, it may be wise to consume fruits
and drinks that contain citrates or citric acid, which also lowers
the risk of developing kidney stones.
Other substances, known as chelating agents, that
could be used for chelation therapy in case of uranium poisoning,
haven't been studied extensively and clinical trials have not been
performed to see if they are suitable for human use. Some of these
chelating agents can be toxic themselves and would have to be administered
under a doctor's supervision. It would seem that consuming citric
acid and citrates, which are already found in fruits and beverages
would be the safest and simplest approach if uranium poisoning is
suspected. Most commercial beverages have less citric acid than citrus
juices and large amounts of added sugar, which may make them less
desirable because of the calories from sugar.
What fruits or beverages have the most citric acid?
Citrus fruits have the greatest amounts of citric
acid. Lemon, lime and grapefruit (and their juices) are the richest
sources of citric acid, with oranges, orange juice and similar fruits
providing relatively large amounts . Squeezing a lemon or lime
into water or other drinks will also provide a good amount. Although
commercial soft drinks add citric acid or sodium citrate, the amounts
are generally less than in the natural juices. Commercial lemonade,
orange juice from concentrate and cranberry juice are also reasonably
It is best to avoid exposure to DU dust by staying
away from vehicles or buildings destroyed by DU. If you are in an
area where there may be DU dust, avoid breathing the dust. Breathing
through several layers of clean (uncontaminated) cotton cloth may
help, if a protective mask is not available. Clean any clothing that
may have been contaminated by washing with baking soda. Absorption
of uranium oxides through the skin may be slow, but it would be wise
to not have uranium oxides on clothing and in constant contact with
the skin over long periods of time. Try to eat citrus fruits and drink
citrus juices or beverages with citric acid or citrates in them to
help minimize the toxic effect of this heavy metal poison. Citric
acid has the added benefit of helping to prevent kidney stone formation.
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