September 1999 |
ToxFAQs™ |
for |
Ionizing Radiation |
(Radiación Ionizante) |
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This fact sheet answers the most frequently
asked health questions about ionizing radiation. For more
information, you may call the ATSDR Information Center at
1-888-422-8737. This fact sheet is one in a series of summaries
about hazardous substances and their health effects. 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.
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HIGHLIGHTS: Ionizing radiation,
like heat and light, is a form of energy. It includes
particles and rays given off by radioactive material,
stars, and high-voltage equipment. Most of it occurs naturally
and some is produced by human activities. At very high
doses, ionizing radiation can cause illness or death.
Any dose could possibly cause cancer, after a several-year
delay. It is not known how many of the 1,517 National
Priorities List sites identified by the Environmental
Protection Agency give off ionizing radiation above background
levels. |
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What
is ionizing radiation? |
Ionizing radiation is any one of several
types of particles and rays given off by radioactive material,
high-voltage equipment, nuclear reactions, and stars. The
types that are normally important to your health are alpha
particles, beta particles, x rays, and gamma rays.
Alpha and beta particles are small, fast-moving
bits of atoms that a radioactive atom gives off when it changes
into another substance. X rays and gamma rays are types
of electromagnetic radiation. These radiation particles and
rays carry enough energy to knock out electrons from atoms
and molecules (such as water, protein, and DNA) that they
hit or pass near. This process is called ionization, which
is why this radiation is called "ionizing radiation."
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What
happens to ionizing radiation when it enters the environment? |
Ionizing radiation, which travels as
fast as the speed of light, hits atoms and molecules in its
path and loses some of its energy with each hit. When all
the energy is gone, there is essentially nothing left. Ionizing
radiation does not make you radioactive - it just leaves some
of its energy inside you or whatever else it hits.
When ionizing radiation from outer space
hits the upper atmosphere, it produces a shower of cosmic
rays that constantly expose everything on earth. Some hit
gases in the air and change them into radioactive material
(such as tritium and carbon 14). Other radioactive materials
are naturally part of the environment, such as the uranium
that has been here since the earth was formed. Still other
radioactive materials are made by industry for smoke detectors,
medical tests, and other uses. These radioactive materials
give off their ionizing radiation over time until all of the
radioactive atoms have decayed.
Whenever radioactive material enters
the environment, it behaves like other substances, getting
into the air, water, soil, plants, and animals while also
giving off radiation.
Some ionizing radiation is made on demand,
such as when doctors take x rays. |
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How
might I be exposed to ionizing radiation? |
You are exposed to low levels of ionizing
radiation from the sun, rocks, soil, natural sources in your
body, fallout from past nuclear weapons tests, some consumer
products, and radioactive materials released from hospitals
and from nuclear and coal power plants.
You are exposed to more if you work as
a pilot, flight attendant, astronaut, industrial and nuclear
power plant worker, or x ray or medical personnel.
You receive additional exposure with
each x ray exam and nuclear medicine test, and the amount
depends on the type and number of tests.
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How
can ionizing radiation affect my health? |
Exposure to low levels of ionizing radiation
from the environment has not been shown to affect human health.
Exposure to high doses of ionizing radiation can result in
skin burns, hair loss, nausea, birth defects, illness, and
death. How you are affected depends on how much ionizing radiation
you received and over what period of time, and personal factors
such as sex, age at the time of exposure, and your health
and nutritional status. Increasing the dose results in a more
severe effect. Increased psychological stress has been shown
in large populations exposed to small doses of radiation from
nuclear accidents. Mental function has been affected in people
exposed before birth to high doses of ionizing radiation.
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How
likely is ionizing radiation to cause cancer? |
Exposure to ionizing radiation may increase
your chance of getting cancer. As with other health effects,
how likely you are to get cancer depends on how much ionizing
radiation you received, your age when exposed, and the type
of cancer.
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How
does ionizing radiation affect children? |
Like adults, children are exposed to
small amounts of ionizing radiation that comes from the soil
where they live, the food and water they eat and drink, the
air they breathe, and from sources that reach earth from space.
There is no evidence that exposure to normal background levels
of ionizing radiation causes health effects in children or
adults.
If a pregnant woman is exposed to high
levels of ionizing radiation, it is possible that her child
may be born with some brain abnormalities. There is an 8-week
period during early pregnancy when an unborn child is especially
sensitive to the effects of higher-than-normal levels of ionizing
radiation. As the levels of ionizing radiation increase, so
does the chance of brain abnormalities.
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How
can families reduce the risk of exposure to ionizing radiation? |
When you or your children receive an
x ray, be sure to correctly wear the protective garments that
are provided. The technician will make sure that only the
area that needs to be x rayed will be exposed to the x ray
beam. If you or your children are treated with a chemical
that has some amount of radioactive material in it to help
a doctor diagnose or treat a disease, be sure to follow the
doctor's directions after you have been treated.
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Is
there a medical test to show whether I've been exposed to ionizing
radiation? |
There are different kinds of tests to
see if you have been exposed to very high doses of ionizing
radiation. One test examines changes in blood cell counts,
but only exposure to high levels of ionizing radiation will
produce detectable changes in blood cell counts. Another test
studies your chromosomes. This test is useful for doses several
times the maximum permissible dose for radiation workers.
There are many ways to see if you have
radioactive material in your body. Radioactive material can
be measured in your blood, feces, saliva, urine, and your
entire body by specialized instruments. The instrument is
chosen based on the type of radiation that is to be measured.
These tests are not available at your doctor's office.
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Has the federal government made recommendations to protect human health? |
The EPA limits the dose from radionuclides
released to the air to 0.1 millirems (mrem)/year. The EPA
has set a drinking water standard for radionuclides of 4 mrem/year
for man-made sources of beta emitters.
The current federal and state regulations
limit workers' doses to 5 rem/year; the limit for an unborn
child of a female radiation worker is 0.5 rem/year; the limit
for the general public is 0.1 rem/year, with provisions for
a limit of 0.5 rem/year under special circumstances.
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References |
Agency for Toxic Substances and Disease
Registry (ATSDR). 1999. Toxicological
Profile for ionizing radiation. Atlanta, GA: U.S. Department
of Health and Human Services, Public Health Service.
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Where can I get more information? |
ATSDR can tell you where to find occupational
and environmental health clinics. Their specialists can recognize,
evaluate, and treat illnesses resulting from exposure to hazardous
substances. You can also contact your community or state health
or environmental quality department if you have any more questions
or concerns. For more information, contact:
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Agency for Toxic Substances and Disease Registry
Division of Toxicology
1600 Clifton Road NE, Mailstop F-32
Atlanta, GA 30333
Phone: 1-888-42-ATSDR (1-888-422-8737)
FAX: (770)-488-4178
Email: ATSDRIC@cdc.gov
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