Everyday Exposure to Radiation
What do you do on a normal day?
Regardless of what you do on a typical day, go to school, work, or stay
home, in each case you are being exposed to radiation. Whether you know
it or not you are being exposed to radioactivity everyday of your life.
Nuclear radiation is all around us in the environment. Low-level
radiation is found in the oceans and waterways, the rocks and soils, the
plant materials and in the atmosphere surrounding the planet. The
radiation that we are exposed to can be said to come from two sources,
that which occur naturally and that which is due to the activities of
Radioactive elements found in rock, soil, water, air, and in food from
the earth make there way in our bodies when we drink water, breath air or
eat foods which contain them. These naturally occurring radioisotopes
such as carbon-14, potassium-40, thorium-223, uranium-238, polonium-218,
and tritium(hydrogen-3) expose us to radiation from within our bodies.
By far, the largest contributor to our daily exposure of radiation is the
natural world, and the major form of natural radiation is radon gas.
Radon-222 is a naturally occuring decay product of uranium-238 which is
commonly found in soils and rocks. Radon-222 is a gas which is odorless,
colorless, tasteless and chemically nonreactive. As it escapes from the
soils and rocks of which it is trapped, it enters the water we drink and
the air we breath.
Since distribution of uranium in the earth's crust varies from place to
place, so does the prevalence of radon gas. In areas where surface rocks
contain a high concentration of uranium, radon gas could enter a home
through a crack in the foundation. A concern for homeowners is the
possibility that radon gas could accumulate to dangerous levels. This is
especially a problem during the winter months when windows and doors are
A survey conducted by the Environmental Protection Agency of radon gas in
homes shows a wide distribution of levels across the United States.
Click here to see what level of radon gas was found in the majority of
homes in the state in which you live. [button]
Another source of natural radiation comes from the interaction of cosmic
rays with the earth's upper atmophere. Cosmic rays permeate all of
space and are composed of highly energized, positively charged particles
as well as high energy photons. Approaching the earth at near the speed
of light, most cosmic rays are blocked by the earth's protective
atmosphere and magnetic field. As a byproduct of the interaction between
cosmic rays (i.e. particles) and the atmosphere, many radioactive
isotopes are formed such as carbon-14.
Cosmic rays are also composed of high energy photons, and not all are
prevented from reaching the earth's surface. It makes sense that the
higher you are in altitude, the more you are exposed to cosmic
radiation. In fact, the average amount of exposure to cosmic radiation
that a person gets in the Unites States roughly doubles for every 6,000 foot
increase in elevation.
The highest mountain in the continental United States is 14,495 feet.
It is not likely that very many people will ever find their way to its
summit, but what mode of transportation often brings us to elevations
greater than this? The answer is flying. Flying can indeed add a few
extra units of exposure to one's daily exposure. Of course, the amount of
extra exposure you get depends on how high the plane flies and how long
you are in the air.
Nuclear Radiation from Human Activities
Although radioisotopes occur naturally in the environment, activities of
humans have brought this radiation closer to us all. For examples, the
bricks, stones, cements and drywalls that we use for the building of our
homes, schools, offices frequently contain uranium ores and are thus
sources of radon.
The human production of tobacco products introduces another way for us to
get exposure to radiation. Smokers recieve a dose of radiation from
polonium-210 which is naturally present in tobacco. Smokers also recieve
an additional dose of radiation from the decay product of radon gas,
polonium-218. Polonium-218 clings to aerosols such as tobacco smoke, and
eventually winds up in the lungs. Once in the lungs, polonium decays by
alpha particle emission and in the process may damage cells.
Although this does not contribute radiation on a daily basis, the medical
field has several ways of causing exposure to an individual. This
exposure results from the attempt to diagnose fractures or cavities using
x-rays, or to diagnose or treat cancer using injected radioisotopes.
Patients are exposed to nuclear radiation in the diagnosis and treatment
of cancer. Additionally, radiologists routinely use radioisotopes of
technetium or thorium to diagnose heart disease.
Depending on one's occupation, the risk of exposure can be greater that
that of the average person. These higher risk occupations include
underground miners, radiologists, medical technologists, nuclear plant
operators, research scientists and pilots.
Is This Exposure Dangerous?
Any amount of radiation can be dangerous because of the potential effect
that it has on living cells. Radiation can disrupt normal chemical
processes of the cells, causing them to grow abnormally or to die. Cells
that are altered by the radiation may go on to produce more abnormal
cells - a process that could eventually lead to cancer.
At low doses, such as have been described here, cells are able to repair
any damage rapidly. Any cells that die due to exposure can be replaced by
the body. If one receives a very high dose, unlike any exposure
mentioned here, the cells may not be able to be replaced fast enough and
tissues or organs may fail to function properly.
Guidelines for levels of exposure have been set by the Deparment of Energy
as means of protecting the public.
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