1.1 What is uranium? |
1.2 What happens to uranium when it enters
the environment? |
1.3 How might I be exposed to uranium? |
1.4 How can uranium enter and leave my
body? |
1.5 How can uranium affect my health? |
1.6 How can uranium affect children? |
1.7 How can families reduce the risk of
exposure to uranium? |
1.8 Is there a medical test to determine
whether I have been exposed
to uranium? |
1.9 What recommendations has the federal
government made to protect human health? |
1.10 Where can I get more information? |
References |
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September 1999 |
Public Health Statement |
for |
Uranium |
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This Public Health Statement is the
summary chapter from the Toxicological
Profile for uranium. It is one in a series of Public Health
Statements about hazardous substances and their health effects.
A shorter version, the ToxFAQs™,
is also available. This information is important because this
substance may harm you. The effects of exposure to any hazardous
substance depend on the dose, the duration, how you are exposed,
personal traits and habits, and whether other chemicals are
present. For more information, call the ATSDR Information
Center at 1-888-422-8737.
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This public health statement tells you
about uranium and the effects of exposure. The Environmental
Protection Agency (EPA) identifies the most serious hazardous
waste sites in the nation. These sitesmake up the National
Priorities List (NPL) and are the sites targeted for long-term
federal cleanup activities. Elevated uranium levels have been
found in at least 54 of the 1,517 current or former NPL sites.
However, the total number of NPL sites evaluated for this
substance is not known. As more sites are evaluated, the sites
at which uranium is found may increase. This information is
important because exposure to this substance may harm you
and because these sites may be sources of exposure.
When a substance is released from a large
area, such as an industrial plant, or from a container, such
as a drum or bottle, it enters the environment. This release
does not always lead to exposure. You are normally exposed
to a substance only when you come in contact with it. You
may been exposed by breathing, eating, or drinking the substance
or by skin contact. However, since uranium is radioactive,
you can also be exposed to its radiation if you are near it.
If you are exposed to uranium, many factors
determine whether you'll be harmed. These factors include
the dose (how much), the duration (how long), and how you
come in contact with it. You must also consider the other
chemicals you're exposed to and your age, sex, diet, family
traits, lifestyle, and state of health.
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1.1
What is uranium? |
Uranium is a natural and commonly occurring
radioactive element. It is found in very small amounts in
nature in the form of minerals, but may be processed into
a silver-colored metal. Rocks, soil, surface and underground
water, air, and plants and animals all contain varying amounts
of uranium. Typical concentrations in most materials are a
few parts per million (ppm). This corresponds to around 4
tons of uranium in 1 square mile of soil 1 foot deep, or about
half a teaspoon of uranium in a typical 8-cubic yard dump
truck load of soil. Some rocks and soils may also contain
greater amounts of uranium. If the amount is great enough,
the uranium may be present in commercial quantities and can
be mined. After the uranium is extracted, it is converted
into uranium dioxide or other chemical forms by a series of
chemical processes known as milling. The residue remaining
after the uranium has been extracted is called mill tailings.
Mill tailings contain a small amount of uranium, as well as
other naturally radioactive waste products such as radium
and thorium.
Natural uranium is a mixture of three
types (or isotopes) of uranium, written as 234U,
235U, and 238U, or as U-234, U-235,
and U-238, and read as uranium two thirty-four, etc. All three
isotopes behave the same chemically, so any combination of
the three would have the same chemical effect on your body.
But they are different radioactive materials with different
radioactive properties. That is why we must look at the actual
percentages of the three isotopes in a sample of uranium to
determine how radioactive the uranium is. For uranium that
has been locked inside the earth for millions of years, we
know the percentage of each isotope by weight and by radioactivity.
By weight, natural uranium is about 0.01% 234U,
0.72% 235U, and 99.27% 238U. About 48.9%
of the radioactivity is associated with 234U, 2.2%
is associated with 235U, and 48.9% is associated
with 238U.
The weight and radioactivity percentages
are different because each isotope has a different physical
half-life. Radioactive isotopes are constantly changing into
different isotopes by giving off radiation. The half-life
is the time it takes for half of that uranium isotope to give
off its radiation and change into a different element. The
half-lives of uranium isotopes are very long (244 thousand
years for 234U, 710 million years for 235U,
and 4½ billion years for 238U). The shorter
half-life makes 234U the most radioactive, and
the longer half-life makes 238U the least radioactive.
If you have one gram of each isotope side by side, the 234U
will be about 20 thousand times more radioactive and the 235U
will be 6 times more radioactive than the 238U.
Uranium is measured in units of mass
(grams) or radioactivity (curies or becquerels), depending
on the type of equipment available or the level that needs
to be measured. The becquerel (Bq) is a new internationalunit,
and the curie (Ci) is a traditional unit; both are currently
used. A Bq is the amount of radioactive material in which
1 atom transforms every second, and a Ci is the amount of
radioactive material in which 37 billion atoms transform every
second. The mass and activity ratios given in the previous
paragraph are those found in rocks inside the earth's crust,
where 1.5 gram of uranium is equivalent to 1 millionth of
a Ci (µCi). Although this ratio can vary in air, soil,
and water, the conversions made in this profile use the 1.5-to-1
ratio unless the actual isotope ratios are known. When both
mass and radioactivity units are shown, the first is normally
the one reported in the literature. Some of the values may
be rounded to make the text easier to read.
The uranium isotopes in the earth were
present when the earth was formed. Both 235U and
238U have such long half-lives that part of the
uranium originally on earth is still here, waiting to give
off its radiation. The original 234U would have
decayed away by now, but new 234U is constantly
being made from the decay of 238U. When 238U
gives off its radiation, it changes or decays through a series
of different radioactive materials, including 234U.
This series, or decay chain, ends when a stable, non-radioactive
substance is made. This element is lead.
For uranium that has been in contact
with water, the natural weight and radioactivity percentages
can vary slightly from the percentages mentioned in the previous
paragraphs. We don't fully understand why that happens in
nature, but measurements show us that it does. The processing
of uranium for industrial and governmental use can also change
the ratios. We give these ratios special names if they were
changed by human activities. If the fraction of 235U
is increased, we call it enriched uranium. However, if the
portion of 235U is decreased, we call it depleted
uranium. The differences between the weight and radioactivity
ratios matter when we want to convert between radioactivity
and mass, and when we talk about how toxic uranium might be.
Depleted uranium is less radioactive than natural uranium,
and enriched uranium is more radioactive than natural uranium.
The industrial process called enrichment
is used to increase the amount of 234U and 235U
and decrease the amount of 238U in natural uranium.
The product of this process is enriched uranium, and the leftover
is depleted uranium. Enriched uranium is more radioactive
than natural uranium, and natural uranium is more radioactive
than depleted uranium. When enriched uranium is 97.5% pure
235U, the same weight of enriched uranium has about
75 times the radioactivity as natural uranium. This is because
enriched uranium also contains 234U, which is even
more radioactive than 235U. The 235U
is responsible for most of the radioactivity in enriched uranium.
Natural uranium is typically about two times more radioactive
than depleted uranium. Other isotopes of uranium called 232U
and 233U are produced by industrial processes.
These are also much more radioactive than natural uranium.
The total amount of natural uranium on
earth stays almost the same because of the very long half-lives
of the uranium isotopes. The natural uranium can be moved
from place to place by nature or by people, and some uranium
is removed from the earth by mining. When rocks are broken
up by water or wind, uranium becomes a part of the soil. When
it rains, the soil containing uranium can be carried into
rivers and lakes. Wind can blow dust that contains uranium
into the air.
Natural uranium is radioactive but poses
little radioactive danger because it gives off very small
amounts of radiation. Uranium transforms into another element
and gives off radiation. In this way uranium transforms into
thorium and gives off a particle called an alpha particle
or alpha radiation. Uranium is called the parent, and thorium
is called the transformation product. When the transformation
productis radioactive, it keeps transforming until a stable
product is formed. During these decay processes, the parent
uranium, its decay products, and their subsequent decay products
each release radiation. Radon and radium are two of these
products. Unlike other kinds of radiation, the alpha radiation
ordinarily given off by uranium cannot pass through solid
objects, such as paper or human skin. For more information
on radiation, see Appendix D and the glossary at the end of
this profile or the ASTDR Toxicological
Profile for Ionizing Radiation.
The main civilian use of uranium is in
nuclear power plants and on helicopters and airplanes. It
is also used by the armed forces as shielding to protect Army
tanks, parts of bullets and missiles to help them go through
enemy armored vehicles, as a source of power, and in nuclear
weapons. Very small amounts are used to make some ceramic
ornament glazes, light bulbs, photographic chemicals, and
household products. Some fertilizers contain slightly higher
amounts of natural uranium.
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1.2
What happens to uranium when it enters the environment? |
Uranium is a naturally occurring radioactive
material that is present to some degree in almost everything
in our environment, including soil, rocks, water, and air.
It is a reactive metal, so it is not found as free uranium
in the environment. In addition to the uranium naturally found
in minerals, the uranium metal and compounds that are left
after humans mine and process the minerals can also be released
back to the environment in mill tailings. This uranium can
combine with other chemicals in the environment to form other
uranium compounds. Each of these uranium compounds dissolves
to its own special extent in water, ranging from not soluble
to very soluble. This helps determine how easily the compound
can move through the environment, as well as how toxic it
might be.
The amount of uranium that has been measured
in air in different parts of the United States by EPA ranges
from 0.011 to 0.3 femtocuries (0.00002 to 0.00045 micrograms)
per cubic meter (m³). (One femtocurie is equal
to 1 picocurie [pCi] divided by 1,000. A picocurie [pCi] is
1 one-trillionth of a curie and a microgram [µg] is
one millionth of a gram. Even at the higher concentration,
there is so little uranium in a cubic meter of air that less
than one atom transforms each day.
In the air, uranium exists as dust. Very
small dust-like particles of uranium in the air fall out of
the air onto surface water, plant surfaces, and soil either
by themselves or when rain falls. These particles of uranium
eventually end up back in the soil or in the bottoms of lakes,
rivers, and ponds, where they stay and mix with the natural
uranium that is already there.
Uranium in water comes from different
sources. Most of it comes from dissolving uranium out of rocks
and soil that water runs over and through. Only a very small
part is from the settling of uranium dust out of the air.
Some of the uranium is simply suspended in water, like muddy
water. The amount of uranium that has been measured in drinking
water in different parts of the United States by EPA is generally
less than 1.5 µg (1 pCi) for every liter of water. EPA
has found that the levels of uranium in water in different
parts of the United States are extremely low in most cases,
and that water containing normal amounts of uranium is usually
safe to drink. Because of the nature of uranium, not much
of it gets into fish or vegetables, and most of that which
gets into livestock is eliminated quickly in urine and feces.
Uranium is found naturally in soil in
amounts that vary over a wide range, but the typical concentration
is 3 µg (2 pCi) per gram of soil. Additional uranium
can be added by industrial activities. Soluble uranium compounds
can combine with other substances in the environment to form
other uranium compounds. Uranium compounds may stay in the
soil for thousands of years without moving downward into groundwater.
When large amounts of natural uranium are found in soil, it
is usually soil with phosphate deposits. The amount of uranium
that has been measured in the phosphate-rich soils of north
and central Florida ranges from 4.5 to 83.4 pCi of uranium
in every gram of soil. In areas like New Mexico, where uranium
is mined and processed, the amount of uranium per gram of
soil ranges between 0.07 and 3.4 pCi (0.1–5.1 micrograms [µg])
of uranium per gram soil). The amount of uranium in soil near
a uranium fuel fabrication facility in the state of Washington
ranges from 0.51 to 3.1 pCi/gram (0.8–4.6 µg uranium/gram
soil), with an average value of 1.2 pCi/gram (1.7 µg
uranium/gram soil). These levels must be carefully compared
with the levels in uncontaminated soil in that area, since
they are within the normal ranges for uncontaminated soil.
Plants can absorb uranium from the soil
onto their roots without absorbing it into the body of the
plant. Therefore, root vegetables like potatoes and radishes
that are grown in uranium- contaminated soil may contain more
uranium than if the soil contained levels of uranium that
were natural for the area. Washing the vegetable or removing
its skin often removes most or all of the uranium.
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1.3
How might I be exposed to uranium? |
Since uranium is found everywhere in
small amounts, you always take it into your body from the
air, water, food, and soil. Food and water have small amounts
of natural uranium in them. People eat about 1–2 micrograms
(0.6–1.0 picocuries) of natural uranium every day with their
food and take in about 1.5 micrograms (0.8 picocuries) of
natural uranium for every liter of water they drink, but they
breathe in much lower amounts. Root vegetables, such as beets
and potatoes, tend to have a bit more uranium than other foods.
In a few places, there tends to be more natural uranium in
the water than in the food. People in these areas naturally
take in more uranium from their drinking water than from their
foods. It is possible that you may eat and drink more uranium
if you live in an area with naturally higher amounts of uranium
in the soil or water or if you live near a uranium-contaminated
hazardous waste site. You can also take in (or ingest) more
uranium if you eat food grown in contaminated soil, or drink
water that has unusually high levels of uranium. Normally,
very little of the uranium in lakes, rivers, or oceans gets
into the fish or seafood we eat. The amounts in the air are
usually so small that they can be safely ignored. People who
are artists, art or craft teachers, ceramic hobbyists, or
glass workers who still use certain banned uranium-containing
glazes or enamels may also be near to higher levels of uranium,
but they will not necessarily take any into their bodies.
People who work at factories that process uranium, work with
phosphate fertilizers, or live near uranium mines have a chance
of taking in more uranium than most other people. People who
work on gyroscopes, helicopter rotor counterbalances, or control
surfaces of airplanes may work with painted uranium metal,
but the coating normally will keep them from taking in any
uranium. People who work with armor-piercing weapons that
contain uranium will be exposed to low levels of radiation
while close to these weapons, but are not likely to take in
any uranium. Those who fire uranium weapons, work with weapons
with damaged uranium, or on equipment which has been bombarded
with these weapons can be exposed to uranium and may wear
protective clothes and masks to limit their intake. Larger-than-normal
amounts of uranium might also enter the environment from erosion
of tailings from mines and mills for uranium and other metals.
Accidental discharges from uranium processing plants are possible,
but these compounds spread out quickly into the air.
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1.4
How can uranium enter and leave my body? |
We take uranium into our bodies in the
food we eat, water we drink, and air we breathe. What we take
in from industrial activities is in addition to what we take
in from natural sources.
When you breathe uranium dust, some of
it is exhaled and some stays in your lungs. The size of the
uranium dust particles and how easily they dissolve determines
where in the body the uranium goes and how it leaves your
body. Uranium dust may consist of small, fine particles and
coarse, big particles. The big particles are caught in the
nose, sinuses, and upper part of your lungs where they are
blown out or pushed to the throat and swallowed. The small
particles are inhaled down to the lower part of your lungs.
If they do not dissolve easily, they stay there for years
and cause most of the radiation dose to the lungs from uranium.
They may gradually dissolve and go into your blood. If the
particles do dissolve easily, they go into your blood more
quickly. A small part of the uranium you swallow will also
go into your blood. The blood carries uranium throughout your
body. Most of it leaves in your urine in a few days, but a
little stays in your kidneys and bones.
When you eat foods and drink liquids
containing uranium, most of it leaves within a few days in
your feces and never enters your blood. A small portion will
get into your blood and will leave your body through your
urine within a few days. The rest can stay in your bones,
kidneys, or other soft tissues. A small amount goes to your
bones and may stay there for years. Most people have a very
small amounts of uranium, about 1/5,000th of the weight of
an aspirin tablet, in their bodies, mainly in their bones.
Although uranium is weakly radioactive,
most of the radiation it gives off cannot travel far from
its source. If the uranium is outside your body, such as in
soil, most of its radiation cannot penetrate your skin and
enter your body. To be exposed to radiation from uranium,
you have to eat, drink, or breathe it, or get it on your skin.
If uranium transformation products are also present, you can
be exposed to their radiation at a distance.
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1.5
How can uranium affect my health? |
To protect the public from the harmful
effects of toxic chemicals and to find ways to treat people
who have been harmed, scientists must determine what the harmful
effects are, how to test for them, how much of the chemical
is required to produce each of the harmful effects, how we
recognize an overexposure, and how to treat it.
One way to see if a chemical will hurt
people is to learn how the chemical is absorbed, used, and
released by the body; for some chemicals, animal testing may
be necessary. Animal testing may also be used to identify
health effects such as kidney or liver damage, cancer, or
birth defects. Without laboratory animals, scientists would
lose a basic method to get information needed to make wise
decisions to protect public health. Scientists have the responsibility
to treat research animals with care and compassion. Laws today
protect the welfare of research animals, and scientists must
comply with strict animal care guidelines.
Uranium is a chemical substance that
is also radioactive. Scientists have never detected harmful
radiation effects from low levels of natural uranium, although
some may be possible. However, scientists have seen chemical
effects. A few people have developed signs of kidney disease
after intake of large amounts of uranium. Animals have also
developed kidney disease after they have been treated with
large amounts of uranium, so it is possible that intake of
a large amount of uranium might damage your kidneys. There
is also a chance of getting cancer from any radio active material
like uranium. Natural and depleted uranium are only weakly
radioactive and are not likely to cause you to get cancer
from their radiation. No human cancer of any type has ever
been seen as a result of exposure to natural or depleted uranium.
Uranium can decay into other radionuclides, which can cause
cancer if you are exposed to enough of them for a long enough
period. Doctors that studied lung and other cancers in uranium
miners did not think that uranium radiation caused these cancers.
The miners smoked cigarettes and were exposed to other substances
that we know cause cancer, and the observed lung cancers were
attributed to large exposures to radon and its radioactive
transformation products.
The chance of getting cancer is greater
if you are exposed to enriched uranium, because it is more
radioactive than natural uranium. Cancer may not become apparent
until many years after a person is exposed to a radioactive
material (from swallowing or breathing it). Just being near
uranium is not dangerous to your health because uranium gives
off very little of the penetrating gamma radiation. However,
uraniumis normally accompanied by the other transformation
products in its decay chain, so you would be exposed to their
radiation as well.
The Committee on the Biological Effects
of Ionizing Radiation (BEIR IV) reported that eating food
or drinking water that has normal amounts of uranium will
most likely not cause cancer or other health problems inmost
people. The Committee used data from animal studies to estimate
that a small number of people who steadily eat food or drink
water that has larger-than-normal quantities of uranium in
it could get a kind of bone cancer called a sarcoma. The Committee
reported calculations showing that if people steadily eat
food or drink water containing about 1 pCi of uranium every
day of their lives, bone sarcomas would be expected to occur
in about 1 to 2 of every million people after 70 years, based
on the radiation dose alone. However, we do not know this
for certain because people normally ingest nly slightly more
than this amount each day, and people who have been exposed
to larger amounts have not been found to get cancer.
We do not know if exposure to uranium
causes reproductive effects in people. Very high doses of
uranium have caused reproductive problems (reduced sperm counts)
in some experiments with laboratory animals. Most studies
show no effects.
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1.6
How can uranium affect children? |
This section discusses potential health
effects from exposures during the period from conception to
maturity at 18 years of age in humans. Potential effects on
children resulting from exposures of the parents are also
considered.
Like adults, children are exposed to
small amounts of uranium in air, food, and drinking water.
However, no cases have been reported where exposure to uranium
is known to have caused health effects in children. It is
possible that if children were exposed to very high amounts
of uranium they might have damage to their kidneys like that
seen in adults. We do not know whether children differ from
adults in their susceptibility to health effects from uranium
exposure.
It is not known if exposure to uranium
has effects on the development of the human fetus. Very high
doses of uranium in drinking water can affect the development
of the fetus in laboratory animals. One study reported birth
defects and another reported an increase in fetal deaths.
However, we do not believe that uranium can cause these problems
in pregnant women who take in normal amounts of uranium from
food and water, or who breathe the air around a hazardous
waste site that contains uranium.
Very young animals absorb more uranium
into their blood than adults when they are fed uranium. We
do not know if this happens in children.
Measurements of uranium have not been
made in pregnant women, so we do not know if uranium can cross
the placenta and enter the fetus. In an experiment with pregnant
animals, only a very small amount (0.03%) of the injected
uranium reached the fetus. Even less uranium is likely to
reach the fetus in mothers exposed by inhaling, swallowing,
or touching uranium. No measurements have been made of uranium
in breast milk. Because of the chemical properties of uranium,
it is unlikely that it would concentrate in breast milk.
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1.7
How can families reduce the risk of exposure to uranium? |
If your doctor finds that you have been
exposed to significant amounts of uranium, ask whether your
children might also be exposed. Your doctor might need to
ask your state health department to investigate.
It is possible that higher-than-normal
levels of uranium may be in the soil at a hazardous waste
site. Some children eat a lot of dirt. You should prevent
your children from eating dirt. Make sure they wash their
hands frequently, and before eating. If you live near hazardous
waste site, discourage your children from putting their hands
in their mouths or from engaging in other hand-to-mouth activities.
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1.8
Is there a medical test to determine whether I have been exposed
to uranium? |
Yes, there are medical tests that can
determine whether you have been exposed by measuring the amount
of uranium in your urine, blood, and hair. Urine analysis
is the standard test. If you take into your body a larger-than-normal
amount of uranium over a short period, the amount of uranium
in your urine may be increased for a short time. Because most
uranium leaves the body within a few days, normally the amount
in the urine only shows whether you have been exposed to a
larger-than-normal amount within the last week or so. If the
intake is large or higher-than-normal levels are taken in
over a long period, the urine levels may be high for a longer
period of time. Many factors can affect the detection of uranium
after e xposure. These factors include the type of uranium
you were exposed to, the amount you took into your body, and
the sensitivity of the detection method. Also, the amount
in your urine does not always accurately show how much uranium
you have been exposed to. If you think you have been exposed
to elevated levels of uranium and want to have your urine
tested, you should do so promptly while the levels may still
be high. In addition to uranium, the urine could be tested
for evidence of kidney damage, by looking for protein, glucose,
and nonprotein nitrogen, which are some of the chemicals that
can appear in your urine because of kidney damage. Testing
for these chemicals could determine whether you have kidney
damage. However, since kidney damage is also caused by several
common diseases, such as diabetes, it would not tell you if
the damage was caused by the presence of uranium in your body.
A radioactivity counter can tell if your
skin is contaminated with uranium, because uranium is radioactive.
If you inhale large amounts of uranium, it may be possible
to measure the amount of radioactivity in your body with special
radiation measurement instruments.
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1.9 What recommendations has the federal government made to protect human health? |
International and national organizations
like the International Commission on Radiological Protection
(ICRP) and the National Council on Radiation Protection and
Measurements (NCRP) provide recommendations for protecting
people from materials, like uranium, that give off ionizing
radiation. The federal government considers these recommendations
and develops regulations and guidelines to protect public
health. Regulations can be enforced by law. Federal
agencies that develop regulations for toxic substances include
the EPA, the Nuclear Regulatory Commission (NRC), the Occupational
Safety and Health Administration (OSHA), and the Food and
Drug Administration (FDA). Recommendations provide valuable
guidelines to protect public health but cannot be enforced
by law. Federal organizations that develop recommendations
for toxic substances include the Agency for Toxic Substances
and Disease Registry (ATSDR) and the National Institute for
Occupational Safety and Health (NIOSH).
Regulations and recommendations can be
expressed as levels that are not to be exceeded in air, water,
soil, or food that are usually based on levels that affect
animals. Then they are adjusted with appropriate safety factors
to help protect people. Sometimes these not-to-exceed evels
differ among federal organizations because of different exposure
times (an 8-hour workday or a 24-hour day), the use of different
animal studies, or other factors.
Recommendations and regulations are also
periodically updated as more information becomes available.
For the most current information, check with the federal agency
or organization that provides it. Some regulations and recommendations
for uranium are discussed below.
EPA has not set a limit for uranium in
air, but it has set a goal of no uranium in drinking water.
EPA calls this the Maximum Contaminant Level Goal (MCLG),
but recognizes that, currently, there is no practical way
to meet this goal. Because of this, EPA proposed in 1991 to
allow up to 20 µg of uranium per liter (20 µg/L)
in drinking water, and states began regulating to achieve
this level. EPA calls this the Maximum Contaminant Level (MCL).
The MCL for uranium is based on calculations that if 150,000
people drink water that contains 20 µg/L of uranium
for a lifetime, there is a chance that one of them may develop
cancer from the uranium in the drinking water. In 1994, EPA
considered changing the MCL to 80 µg per liter based
on newer human intake and uptake values and the high cost
of reducing uranium levels in drinking water supplies. In
1998, EPA temporarily dropped its 1991 limit, but is currently
working to develop an appropriate limit based on a broader
range of human and animal health studies. ATSDR, other federal
agencies, Canada, and other professionals are advising EPA
regarding a new MCL. Canada is currently developing its own
national guideline value because that country has the richest
known uranium ore deposits in the world and high uranium concentrations
in some of its well water.
EPA has also decided that any accidental
uranium waste containing 0.1 curies of radioactivity (150
kilograms) must be cleaned up. EPA calls this the Reportable
Quantity Accidental Release. EPA also has established a standard
for uranium mill tailings. In the workplace, NIOSH/OSHA has
set a Recommended Exposure Limit (REL) and a Permissible Exposure
Limit (PEL) of 0.05 mg/m³ (34 pCi/m³) for uranium
dust, while the NRC has an occupational limit of 0.2 mg/m³(130
pCi/m³). The NRC has set uranium release limits at 0.06
pCi/m³ (0.09 µg/m³) of air and 300 pCi/liter
(450 µg/liter) of water. NRC and OSHA expect that the
public will normally be exposed to much lower concentrations.
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1.10 Where can I get more information? |
If you have any more questions or concerns, please contact
your community or state health or environmental quality department or:
Agency for Toxic Substances and Disease Registry
Division of Toxicology
1600 Clifton Road NE, Mailstop F-32
Atlanta, GA 30333
Information line and technical assistance:
Phone: 888-422-8737
FAX: (770)-488-4178
ATSDR can also tell you the location of occupational and environmental health
clinics. These clinics specialize in recognizing, evaluating, and treating illnesses
resulting from exposure to hazardous substances.
To order toxicological profiles, contact:
National Technical Information Service
5285 Port Royal Road
Springfield, VA 22161
Phone: 800-553-6847 or 703-605-6000
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References |
Agency for Toxic Substances and Disease
Registry (ATSDR). 1999. Toxicological
profile for uranium. Atlanta, GA: U.S. Department of Health
and Human Services, Public Health Service.
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