1.1 What is cesium? |
1.2 What happens to cesium when it enters the environment? |
1.3 How might i be exposed to cesium? |
1.4 How can cesium enter and leave my
body? |
1.5 How can cesium affect my health? |
1.6 How can cesium affect children? |
1.7 How can families reduce the risk of
exposure to cesium? |
1.8 Is there a medical test to determine
whether i have been exposed to cesium? |
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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April 2004 |
Public Health Statement |
for |
Cesium |
(Cesio) |
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This Public Health Statement is the
summary chapter from the Toxicological
Profile for cesium. 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 cesium and the effects of exposure.
The Environmental Protection Agency (EPA)
identifies the most serious hazardous waste sites in the nation.
These sites make up the National Priorities List (NPL) and
are the sites targeted for long-term federal cleanup activities.
Stable (not radioactive) cesium (133Cs) has been
identified in at least 8 of the 1,636 hazardous waste sites
that have been proposed for inclusion on the EPA National
Priorities List (NPL) (HazDat 2003). It was reported that
134Cs (radioactive) has been found in at least
3 of the 1,636 current or former NPL sites and 137Cs
(radioactive) has been detected in at least 23 of the 1,636
current or former NPL sites. However, the number of sites
evaluated for cesium is not known. As more sites are evaluated,
the sites at which cesium 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 exposed to a substance
when you come in contact with it. You may be exposed by breathing,
eating, or drinking the substance, or by skin contact. If
the substance is radioactive, you may also be exposed to radiation
if you are near it.
External exposure to radiation may occur
from natural or man-made sources. Naturally occurring sources
of radiation are cosmic radiation from space or radioactive
materials in soil or building materials. Man-made sources
of radioactive materials are found in consumer products, industrial
equipment, atom bomb fallout, and to a smaller extent from
hospital waste, medical devices, and nuclear reactors.
If you are exposed to cesium, 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 cesium? |
Cesium is a naturally-occurring element
found in rocks, soil, and dust at low concentrations. Granites
contain an average cesium concentration of about 1 part of
cesium in a million parts of granite (ppm) and sedimentary
rocks contain about 4 ppm. Natural cesium is present in the
environment in only one stable form, as the isotope 133Cs.
Pure cesium metal is silvery white in color and very soft,
but pure cesium is not expected to be found in the environment.
Pure cesium metal reacts violently with air and water, resulting
in an explosion-like reaction. Cesium compounds do not react
violently with air or water and are generally very soluble
in water. The most important source of commercial cesium is
a mineral known as pollucite, which usually contains about
5-32% cesium oxide (Cs2O). No known taste or odor
is associated with cesium compounds. Cesium is not mined or
produced in the United States and very little is imported
from other countries. There are relatively few commercial
uses for cesium metal and its compounds. Sometimes cesium
is used as a getter for residual gas impurities in vacuum
tubes and as a coating in tungsten filaments or cathodes of
the tubes. Crystalline cesium iodide and cesium fluoride are
used in scintillation counters, which convert energy from
ionizing radiation into pulses of visible light for radiation
detection and spectroscopy. Cesium is also used in highly
accurate atomic clocks.
Radioactive forms of cesium are produced
by the fission of uranium in fuel elements (fuel rods) during
the normal operation of nuclear power plants, or when nuclear
weapons are exploded. Radioactive forms of cesium are unstable
and eventually change into other more stable elements through
the process of radioactive decay. The two most important radioactive
isotopes of cesium are 134Cs and 137Cs.
Radioactive isotopes are constantly decaying or changing into
different isotopes by giving off radiation. Each atom of 134Cs
changes into either xenon 134 (134Xe) or barium
134 (134Ba), neither of which is radioactive, while
each atom of 137Cs decays to barium 137 (137Ba),
which is also not radioactive. As 134Cs and 137Cs
decay, beta particles and gamma radiation are given off. The
half-life is the time it takes for half of that cesium isotope
to give off its radiation and change into a different element.
The half-life of 134Cs is about 2 years and the
half-life of 137Cs is about 30 years.
Quantities of radioactive cesium, as
well as other radioactive elements, are measured in units
of mass (grams) or radioactivity (curies or becquerels). Both
the curie (Ci) and the becquerel (Bq) describe the rate of
decay and tell us how much a radioactive material decays every
second. The becquerel is a new international unit known as
the SI unit, and the curie is an older, traditional unit;
both are currently used. A becquerel is the amount of radioactive
material in which 1 atom transforms every second. One curie
is the amount of radioactive material in which 37 billion
atoms transform every second; this is approximately equivalent
to the radioactivity of 1 gram of radium.
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1.2
What happens to cesium when it enters the environment? |
Naturally-occurring cesium occurs in
the environment mostly from the erosion and weathering of
rocks and minerals. The mining and milling of certain ores
can also release cesium to the air, water, and soil. Radioactive
cesium is released to the environment during the normal operation
of nuclear power plants, explosion of nuclear weapons, and
accidents involving nuclear power plants or nuclear powered
satellites or submarines.
Nonradioactive (stable) cesium can be
neither created nor destroyed under typical environmental
conditions, but can react with other compounds found in the
environment and change into different cesium compounds. Radioactive
decay decreases the concentration of 134Cs and
137Cs. Both stable and radioactive cesium are the
same element and behave in a similar manner chemically and
in the body. Cesium compounds can travel long distances in
the air before being brought back to the earth by rainfall
and gravitational settling. In water and moist soils, most
cesium compounds are very soluble. Cesium binds strongly to
most soils and does not travel far below the surface of the
soil.
Consequently, cesium is not readily available
for uptake by vegetation through roots. However, radiocesium
can enter plants upon falling onto the surface of leaves.
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1.3
How might i be exposed to cesium? |
You can be exposed to stable or radioactive
cesium by breathing air, drinking water, or eating food containing
cesium. The level of cesium in air and water is generally
very low. The concentration of natural cesium in air is generally
less than 1 nanogram (1 nanogram equals 1/1,000,000,000 of
a gram) per cubic meter of air (ng/m3). The amount
of cesium in drinking water is ordinarily about 1 microgram
(1 microgram equals 1/1,000,000 of a gram) per liter of water
(µg/L). On average, a person swallows about 10 µg
of stable cesium per day in food and water, and breathes about
0.025 µg per day. Plants and animals contain cesium
at concentrations of about 1-300 ng/g.
Radioactive cesium has been detected
in surface water and in many types of food. This includes
breast milk and pasteurized milk. The amount of radioactive
cesium in food and milk is highly dependent upon several factors.
The most important factor is whether or not there has been
recent fallout from a nuclear explosion such as a weapons
test or an accident that has occurred at a nuclear power plant.
However, atmospheric testing of nuclear weapons was halted
many years ago, and there have only been two major reactor
accidents at nuclear plants where radiocesium was released
in significant amounts. The two accidents occurred in Windscale,
England in 1957 and Chernobyl, Russia in 1986. You should
understand that cesium only contributed a small fraction of
the total radioactivity released following these events. The
radiological impacts in Europe from 137Cs and 134Cs
released from the Chernobyl accident, however, were great.
These included environmental dispersion of radiocesium and
uptake in reindeer, caribou, and livestock. Furthermore, the
consequences of external exposure to gamma radiation and beta
particles are not unique to 137Cs and 134Cs,
but are very similar for all gamma and beta emitting radionuclides.
People who work in industries that process or use natural
cesium or cesium compounds can be exposed to higher-than-normal
levels of cesium. An estimated 16,461 workers (4,276 of these
are female) are potentially exposed to natural cesium and
cesium compounds in the United States. If you work in the
nuclear power industry, you may also be exposed to higher-than-normal
levels of radioactive cesium, but there are many precautionary
measures taken at these facilities to minimize this exposure.
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1.4
How can cesium enter and leave my body? |
Stable and radioactive cesium can enter
your body from the food you eat or the water you drink, from
the air you breathe, or from contact with your skin. When
you eat, drink, breathe, or touch things containing cesium
compounds that can easily be dissolved in water, cesium enters
your blood and is carried to all parts of your body. Cesium
is like potassium; it enters cells and helps to maintain a
balance of electrical charges between the inside and the outside
of cells so that cells can perform tasks that depend on those
electrical charges. Cells like muscle cells and nerve cells
require changing electrical charges in order to function properly
and allow you to think and move.
Once cesium enters your body, your kidneys
begin to remove it from the blood; some cesium is quickly
released from your body in the urine. A small portion is also
released in the feces. Some of the cesium that your body absorbs
can remain in your body for weeks or months, but is slowly
eliminated from your body through the urine and feces.
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1.5
How can cesium 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 use many tests.
One way to see if a chemical will hurt
people is to learn how the chemical is absorbed, used, and
released by the body. In the case of a radioactive chemical,
it is also important to gather information concerning the
radiation dose and dose rate to the body. For some chemicals,
animal testing may be necessary. Animal testing may also be
used to identify health effects such as 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.
You are not likely to experience any
health effects that could be related to stable cesium itself.
Animals given very large doses of cesium compounds have shown
changes in behavior, such as increased activity or decreased
activity, but it is highly unlikely that you would breathe,
eat, or drink amounts of stable cesium large enough to cause
similar effects. If you were to breathe, eat, drink, touch,
or come close to large amounts of radioactive cesium, cells
in your body could become damaged from the radiation that
might penetrate your entire body, much like x-rays, even if
you did not touch the radioactive cesium. You would probably
experience similar effects if you were exposed to any other
substance with similar radioactivity. You might also experience
acute radiation syndrome, which includes such effects as nausea,
vomiting, diarrhea, bleeding, coma, and even death. A number
of people in Brazil, who handled radioactive cesium that was
scavenged from a medical machine used for radiation therapy,
became sick from exposure to the radiation; a few of them
died. But people exposed to radioactive cesium that has been
widely dispersed in air, water, soil, or foods following nuclear
bombings or accidents have not been exposed to amounts large
enough to cause the same effects.
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1.6
How can cesium affect children? |
This section discusses potential health
effects from exposures during the period from conception to
maturity at 18 years of age in humans.
Children can be affected by cesium in
the same ways as adults. Stable cesium is not likely to affect
the health of children, but large amounts of gamma radiation,
from sources such as radioactive cesium, could damage cells
and might also cause cancer. Short exposure to extremely large
amounts of radiation might cause nausea, vomiting, diarrhea,
bleeding, coma, and even death. In addition, if babies were
to be exposed to enough radiation while in their mother's
womb during the time when their nervous system is rapidly
developing, they could experience changes in their brains
that could result in changes in behavior or decreased mental
abilities. However, it is unlikely that children or babies
would be exposed to enough gamma radiation from a radioactive
cesium source to do such damage to their bodies.
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1.7
How can families reduce the risk of exposure to cesium? |
If your doctor finds that you have been
exposed to significant amounts of cesium, ask whether your
children might also be exposed. Your doctor might need to
ask your state health department to investigate.
Since cesium is naturally found in the
environment, we cannot avoid being exposed to it. However,
the relatively low concentrations of stable cesium do not
warrant any immediate steps to reduce exposure. You are unlikely
to be exposed to high levels of radioactive cesium unless
there is a fuel meltdown and accidental release at a nuclear
power plant or a nuclear weapon has been detonated. In such
cases, follow the advice of public health officials who will
publish guidelines for reducing exposure to radioactive material
when necessary.
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1.8
Is there a medical test to determine whether I have been exposed
to cesium? |
Everyone has small amounts of cesium
in their body. Laboratories use special techniques to measure
the amount of cesium in body fluids such as blood and urine,
as well as in feces or other human samples. This can give
an indication of whether a person has been exposed to levels
of cesium that are higher than those normally found in food,
water, or air. Special radiation detectors can be used to
detect if a person has absorbed radioactive cesium. It is
difficult to determine if a person has been exposed only to
external radiation from radioactive cesium. Health professionals
examining people who have health problems similar to those
resulting from radiation exposure would need to rely on additional
information, such as the testing of blood samples for cell
counts and chromosomal damage, in order to establish if such
people had been affected by being near a source of radioactivity.
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1.9
What recommendations has the federal government made to protect
human health? |
The federal government develops regulations
and recommendations to protect public health. Regulations
can be enforced by law. Federal agencies that develop regulations
for toxic substances include the Environmental Protection
Agency (EPA), the Occupational Safety and Health Administration
(OSHA), the Food and Drug Administration (FDA), and the U.S.
Nuclear Regulatory Commission (USNRC).
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), the National Institute for Occupational Safety and
Health (NIOSH), and the FDA.
Regulations and recommendations can be
expressed in not-to-exceed levels in air, water, soil, or
food that are usually based on levels that affect animals;
they are then adjusted to help protect people. Sometimes these
not-to-exceed levels 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 cesium include the following:
There are few guidelines for compounds
of stable cesium. Based on eye irritation, the NIOSH has established
a recommended exposure limit (REL) for cesium hydroxide of
2 mg/m3 as a time-weighted average (TWA) for up
to a 10-hour workday and a 40-hour workweek. The American
Conference of Governmental Industrial Hygienists (ACGIH) has
assigned cesium hydroxide a threshold limit value (TLV) of
2 mg/m3 as a TWA for a normal 8-hour workday and
a 40-hour workweek, based on respiratory and eye irritation.
The NRC established guidelines for radioactive
cesium that include occupational inhalation exposure Derived
Air Concentrations (DACs) of 0.00000004 µCi/mL (4x10-8
µCi/mL) for 134Cs and 0.00000006 µCi/mL
(6x10-8 µCi/mL) for 137Cs. Annual
Limits on Intake (ALIs) for on-the-job exposure are 100 µCi
(1x102 µCi) for 134Cs and 200 µCi (2x102
µCi) for 137Cs.
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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). 2004. Toxicological
profile for cesium. Atlanta, GA: U.S. Department of Health
and Human Services, Public Health Service.
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