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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.
A-1 House Inspectors offers
radon testing using continuous
monitoring devices. The test is
performed over a minimum 48 hour
period, after which, the results
are determined by EPA approved
software. The radon report is
then delivered to the client in
letter form stating the results.
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.
Click
Here
for information on Radon
Mitigation techniques.
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 non-occupational 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 radionuclide
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 nuclei, 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 tightly 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.
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