For
more information from the EPA go to
Radon
Publications. Especially note section 3B of the contents.
Radon Testing: Be sure that the testing
includes enviromental monitoring and that the tester is
Nationally certified for testing and analyses by either:
National Radon Proficiency
Program or National Radon
Safety Board
Radon Mitigation: Here is a resource for
radon mitigation: Mr. Brett Strimple
Integrity Radon
Systems
What is radon?
   Radon is a cancer-causing radioactive
gas. You cannot see, smell or taste radon but it may be
a problem in your home. When you breathe air containing
radon, you increase your risk of getting lung cancer. In
fact, the Surgeon General has warned that radon is the second
leading cause of lung cancer in the United States today.
If you smoke and your home has high radon levels, your risk
of lung cancer is especially high.
Radon (A more scientific description)
   A gaseous highly radioactive element.
Discovered by English physicist Ernest Rutherford in 1899.
Although the discovery is *also* credited to German physicist
Friedrich Ernst Dorn in 1900, it may be fairer to say that
Rutherford discovered radon's alpha radiation and that Dorn
found that radium was giving off a gas. (We welcome input
from anyone with additional documentation concerning this
issue.) E-mail to: Radon's Discoverer?
   Radonis a colorless, chemically unreactive
inert gas, it is the densest gas known. The gas and its
highly radioactive (radioactivity described) metallic daughter
products emit alpha and beta particles and gamma rays. It
has been used in the treatment of cancer by radiotherapy.
In homes and other buildings, in some areas of the world,
radon produced by the radioactive decay of uranium-238 present
in soil and rock can reach levels regarded as dangerous.
(Chemical Symbol/Element Number: Rn222)
Should you test for radon?
   Testing is the only way to know your
home’s radon levels. There are no immediate symptoms that
will alert you to the presence of radon. It typically takes
years of exposure before any problems surface and then it
is too late.
   The U.S. Environmental Protection
Agency, Surgeon General, American Lung Association, American
Medical Association and National Safety Council all recommend
testing your home for radon.
Can you fix the problem?
   If you find that your home has high
radon levels, there are ways to reduce the concentrations.
Even very high levels can be reduced to acceptable levels.
Most radon problems can be fixed by a do-it-yourselfer for
for less than $500.
RADIATION AND RISK FACTS
   The alpha radiation emitted by radon
is the exact same alpha radiation that is emitted by any
other alpha generating radiation source, like plutonium.
   A family whose home has radon levels
of 4 pCi/l is exposed to approximately 35 times as much
radiation as the NUCLEAR REGULATORY COMMISSION allows if
they were standing next to the fence of a radioactive waste
site. (25 mrem limit, 800 mrem exposure)
   An elementary school student that
spends 8 hours per day and 180 days per year in a classroom
with 4 pCi/l of radon will receive nearly 10 times as much
radiation as the NUCLEAR REGULATORY COMMISSION allows at
the edge of a nuclear power plant.(25 mrem limit, 200 mrem
exposure)
   Most United States Environmental Protection
Agency (EPA) lifetime safety standards for carcinogens are
established based on a 1 in 100,000 risk of death. Most
scientists agree that the risk of death for radon at 4 pCi/l
is approximately 1 in 100. At the 4 pCi/l EPA action guideline
level radon carries approximately 1000 times the risk of
death as any other EPA carcinogen.
   Radon induced lung cancer costs the
United States over $2 Billion dollars per year in both direct
and indirect health care costs.
(Based on National Cancer Institute statistics of 14,400
annual radon lung cancer deaths) (Oster, Colditz & Kelley,
1984)
CANCER AND SCIENTIFIC FACTS
CARCINOGENICITY
   Radon's primary hazard is caused from
inhalation of the gas and its highly radioactive heavy metallic
decay products (Polonium, Lead, and Bismuth) which tend to
collect on dust in the air. The problem arises when these
elements stick to the delicate cells lining the passageways
leading into the lungs.
   There is sufficient evidence for the
carcinogenicity of radon and its isotopic forms, radon-222
and radon-220, in experimental animals. When administered
by inhalation, preceded by a single exposure to cerium hydroxide
dust, radon induced pulmonary adenomas, adenocarcinomas, invasive
mixed adenosquamous carcinomas, and squamous cell carcinomas
in male rats. Extrapulmonary metastases occurred in only one
animal. Most or all of the tumors were believed to be bronchiolar
or bronchio-alveolar in origin. Radon decay products in combination
with uranium-ore dust induced a progression of activity from
single basal cell hyperplasia in bronchioles to malignant
tumors in male hamsters when exposed by inhalation. Lung tumors
observed were adenomas, adenocarcinomas, and squamous cell
carcinomas; bronchiolar and alveolar metaplasia, adenomatous
lesions, fibrosis, and interstitial pneumonia were also observed.
When administered by inhalation in combination with decay
products, uranium-ore dust, and cigarette smoke, radon-induced
nasal carcinomas, epidermoid carcinomas, bronchio-alveolar
carcinomas, and fibrosarcoma were observed in dogs of both
sexes. In general, a significant increase was observed in
respiratory tract tumors in rats and dogs in comparison with
unexposed animals. A dose- response relationship was noted
in those experiments with rats in which radon was tested.
In most instances, tumors at sites other than the lung were
not reported, but in one study, mention was made of tumors
of the upper lip and urinary tract in rats.
   An IARC Working Group reported that
there is sufficient evidence for the carcinogenicity of radon
and its decay products in humans. Increased incidences of
lung cancer have been reported from numerous epidemiologic
studies of groups occupationally exposed to high doses of
radon, especially underground hard rock miners. These include
particularly uranium miners, but also groups of iron-ore and
other metal miners, and one group of fluorspar miners. Strong
evidence for exposure response relationships has been obtained
from several studies, in spite of uncertainties that affect
estimates of the exposure of the study populations to radon
decay products. Several small case-control studies of lung
cancer have suggested a higher risk among individuals living
in houses known or presumed to have higher levels of radon
and its decay products than among individuals with lower presumed
exposure in houses. The evidence on the interaction of radon
and its decay products with cigarette smoking with regard
to lung cancer does not lead to a simple conclusion. The data
from the largest study are consistent with a multiplicative
or submultiplicative model of synergisms and reject an additive
model. In many studies of miners and in one of presumed domestic
exposure, small cell cancers accounted for a greater proportion
than expected of the lung cancer cases. In one population
of uranium miners, this proportion has been declining with
the passage of time. Because of the limited scale of epidemiologic
studies of nonoccupational exposure to radon decay products
available at the time reviews were made, quantification of
risk has been based only on data of miners' experience. An
IARC Working Group considered that the epidemiologic evidence
does not lead to a firm conclusion concerning the interaction
between exposure to radon decay products and tobacco smoking.
Most of the epidemiologic studies involve small numbers of
cases, and the analytical approaches for assessing interaction
have been variable and sometimes inadequate.
PROPERTIES
   Radon was discovered in 1900 by Friedrich
Ernst Dorn, (Germany). Named after the element "radium" (radon
was called niton at first, from the Latin word "nitens" meaning
"shining") but has been called radon since 1923. It is an
essentially inert, colorless, odorless gas at ordinary temperatures.
Its melting point is 202 degrees K and the boiling point is
211 degrees K. When cooled below the freezing point radon
exhibits a brilliant phosphorescence which becomes yellow
as the temperature is lowered and orange-red at the temperature
of liquid air.
   The atomic radius is 1.34 angstroms
and it is the heaviest known gas, being nine times denser
than air. Because it is a single atom gas (unlike oxygen,
O2, which is comprised of two atoms) it easily penetrates
many common materials like paper, leather, low density plastic
(like plastic bags, etc.) most paints, and building materials
like gypsum board (sheetrock), concrete block, mortar, sheathing
paper (tarpaper), wood paneling, and most insulation.
   Radon is also fairly soluble in water
and organic solvents. Although reaction with other compounds
is comparatively rare, it is not completely inert and forms
stable molecules with highly electronegative materials. Radon
is considered a noble gas that occurs in several isotopic
forms. Only two are found in significant concentrations in
the human environment: radon-222, and radon-220. Radon-222
is a member of the radioactive decay chain of uranium-238,
and radon-220 is formed in the decay chain of thorium-232.
Radon-222 decays in a sequence of radionuclides called radon
decay products, radon daughters, or radon progeny. It is radon-222
that most readily occurs in the environment. Atmospheric releases
of radon-222 results in the formation of decay products that
are radioisotopes of heavy metals (polonium, lead, bismuth)
and rapidly attach to other airborne materials such as dust
and other materials facilitating inhalation.
USE
   Radon is a noble gas. Only two of its
isotopic forms are found in significant concentrations in
the human environment: radon-222 and radon-220. Their decay
products are not gases and occur as unattached ions or atoms,
condensation nuceli, or attached to particles. This decay
product of uranium-238 is commonly found in uranium mines.
Radon has been used in some spas for presumed medical effects.
In addition, radon is used to initiate and influence chemical
reactions and as a surface label in the study of surface reactions.
It has been obtained by pumping the gases off of a solution
of a radium salt, sparking the gas mixture to combine the
hydrogen and oxygen, removing the water and carbon dioxide
by adsorption, and freezing out the radon.
PRODUCTION
   Radon is not produced as a commercial
product. Radon is a naturally occurring radioactive gas and
comes from the natural breakdown (radioactive decay) of uranium.
Most soils contain varying amounts of uranium. It is usually
found in igneous rock and soil, but in some cases, well water
may also be a source of radon.
EXPOSURE
   The primary routes of potential human
exposure to radon are inhalation and ingestion. Radon in the
ground, groundwater, or building materials enters working
and living spaces and disintegrates into its decay products.
In comparison with levels in outdoor air, the concentrations
of radon and its decay products to which humans are exposed
in confined air spaces, particularly in underground work areas
such as mines and buildings, are elevated. Although high concentrations
of radon in groundwater may contribute to human exposure through
ingestion, the radiation dose to the body due to inhalation
of radon released from water is usually more important. Concentrations
of radon decay products measured in the air of underground
mines throughout the world vary by several orders of magnitude.
In countries for which data were available, concentrations
of radon decay products in underground mines are now typically
less than 1000 Bq/m3 EEC Rn (approx. 28 pCi/l). The average
radon concentrations in houses are generally much lower than
the average radon concentrations in underground ore mines.
Workers are exposed to radon in several occupations. Underground
uranium miners are exposed to the highest levels of radon
and its decay products. Other underground workers and certain
mineral processing workers may also be exposed to significant
levels. Exhalation of radon from ordinary rock and soils and
from radon- rich water can cause significant radon concentrations
in tunnels, power stations, caves, public baths, and spas.
Peripheral lymphocyte chromosomes from 80 underground uranium
miners and 20 male controls in the Colorado plateau were studied.
Taken into account were confounding factors such as cigarette
smoking and diagnostic radiation. Groups that were increasingly
exposed to radon and its decay products were selected. Significantly
more chromosomal aberrations were observed among miners with
atypical bronchial cell cytology, suspected carcinoma, or
carcinoma in situ than among miners with regular or mildly
atypical cells, as evaluated by sputum cell cytology.
   The Environmental Protection Agency
(U.S. E.P.A.) and the Surgeons General's Office have urged
widespread testing for radon. They estimated that as many
as 20,000 lung cancer deaths are caused each year by radon.
Next to smoking, radon is the second leading cause of lung
cancer. EPA says that nearly 1 in 3 homes checked in seven
states and on three Indian lands had screening levels over
4 pCi/L, the EPA's recommended action level for radon exposure.
   Radon is a national environmental health
problem. Elevated radon levels have been discovered in virtually
every state. The EPA estimates that as many as 8 million homes
throughout the country have elevated levels of radon. State
surveys to date show that 1 out of 5 homes has elevated radon
levels. Radon seeps into homes from the surrounding soil through
cracks and other openings in the foundation. Indoor radon
has been judged to be the most serious environmental carcinogen
to which the general public is exposed and which the EPA must
address. Based on current exposure and risk estimates, radon
exposure in single-family houses may be a causal factor in
as many as 20,000 of the total lung cancer fatalities which
occur each year. Radon decay products (polonium- 218 and polonium-214,
solid form) can attach to the surface of aerosols, dusts,
and smoke particles which may be inhaled, and become deeply
lodged or trapped in the lungs. Once lodged, they can radiate
and penetrate the cells of mucous membranes, bronchi, and
other pulmonary tissues.
   Some scientific studies of radon exposure
indicate that children may be more sensitive to radon. This
may be due to their higher respiration rate and their rapidly
dividing cells, which may be more vulnerable to radiation
damage.
Radioactivity --- a Summary:
   The spontaneous disintegration or decay
of the nucleus of an atom by emission of particles, usually
accompanied by electromagnetic radiation. Natural radioactivity
is exhibited by several elements, including uranium, radium,
radon gas, and radon's daughters. The radiation produced is
of three types: the alpha particle with relatively weak penetration
power, which is a nucleus (two protons and two neutrons) of
an ordinary helium atom; the beta particle with moderate penetration
power, which is a high-speed electron or, in some cases, a
positron (the electron's antiparticle); and gamma radiation,
which is a type of electromagnetic radiation with very short
wavelengths resulting in very high penetration power. The
rate of disintegration of a radioactive substance is commonly
designated by its half-life, which is the time required for
one half of a given quantity of the substance to decay.
   For example, if you had a two liter
bottle (think of the large soda bottle in the fridge) that
was filled with radon gas and then tighly sealed, at the end
of one half-life (approximately 92 hours or almost 4 days)
there would only be one liter left in the bottle.
   Another issue to consider is the *unusual*
property of the radioactive decay chain of uranium/radium/radon.
What makes this seem unusual is that a gas is produced from
a radioactive solid element (a rock) and then the radioactive
gas changes back into radioactive heavy metallic particles.
This process and their atomic size (extremely small) makes
possible the transport of radioactive atoms through a relatively
static environment. In other words, radon's extended half-life
(it takes about a month for a specific amount of it to decay
to almost nothing) provides enough time for the gas to migrate
through cracks and crevices in building foundations, then
into the internal air volume where it changes into the more
harmful radioactive heavy metals.
   This gas and the resulting very small
metallic particles (so small that they will float in air)
move quickly through a building or home, contaminating the
air. An analogy that makes this easier to understand is to
think how easily some can detect the presence of a smoker
in another part of the building or the cooking of coffee or
bacon in the kitchen on Sunday morning. In other words, almost
nothing will stop this gas from moving from the basement to
other parts of a house if it makes its way into the basement
in the first place. Be sure you visit our Radon FAQ page for
answers on how to stop this gas before it enters your home.