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The Facts about Granite, Radiation and Radon
Radon and radiation in granite are intertwined, as radon is a product of
radioactive elements. It can get confusing at times but some basic research on
the internet can simplify things or you can read this page for some basic facts
about radioactivity and Radon.
Almost all granites and natural stone have some level of radioactive minerals in
them. Granite gives off radiation as these radioactive materials decay.
Although the uranium is generally not concentrated enough to make granite a
uranium ore, the leaching and erosion of granite has helped produce most of
the uranium ore deposits around the world.
Radiation will vary in different granite materials, so much so that the Chinese
enacted radiation standards years ago and actually prohibit the export of the
safer, lower radiation level granite. Think about that, any Chinese granite
imported into the United States or elsewhere is considered too dangerous to be
put in a Chinese dwelling. The health risks from granite radiation are small yet
not as small as other health risks. For instance, the granite in the Thomas
Jefferson building in Washington D.C., will give you an incremental cancer risk
50 times greater than the Super Fund clean up trigger levels.
At this Canadian radon workshop, they discussed one study that said that
radiation has been shown to affect cardiovascular disease, then discussed
whether radon would also.
So what is the danger of radon in a granite countertop?
Almost all experts agree that no level of ionizing radiation is completely safe and
that radon adds to the background radiation that all of us are exposed to. One
physics expert has expressed the risks of radiation in terms of "loss of life
expectancy" and placed the loss of life expectancy of 1 Milli rem of radiation at
1.2 minutes, and the loss of life expectancy of 20 hours for a years exposure to
1 pCi/l in your home. The EPA recommends action when radon reaches 4 pCi/l
One radon site, says this about the health risks of radon.
"One would think that radon was the least of our radiation problems since it is an
inert gas. That would be so except that when we breathe, we are constantly
passing air into our lungs and out of them. In this process, the radon gas simply
goes in and out, doing little damage, but the radon daughters, being basically
solid materials, and sometimes being electrically charged, can stick to the
surfaces of our bronchial tubes. This puts them right where they can do the
most harm, for the cells lining our bronchial tubes are among the cells of our
body most sensitive to radiation-induced cancer. The alpha particles emitted in
the decay of radon daughters, in spite of their poor penetrating power, can
reach these very sensitive cells because they are deposited so close to them.
To make matters very much worse, alpha particles are much more efficient than
other types of radiation for inducing cancer. The very fact that they are not
penetrating means that they dump a lot of their energy into each of the
biological cells they pass through, and this large release of energy into a single
cell is just what is needed to initiate a cancer. As a result an alpha particle is a
hundred times more likely to cause cancer than other types of radiation, if it can
reach the target cells. Our breathing processes allows the alpha particles from
radon daughters to reach these cells."
Searching the web will bring up other opinions like this one from the University of
Georgia. Even the mention of granite having radon can cause a heated debate
such as this thread of a consumer forum with granite fabricators attempting to
minimize any threat and homeowners that purchased granite attempting to
defend their choice or worried about future resale value. Once some research
is done, the subject becomes a little clearer.
This site explains in detail why the biological effects of radiation should be of
concern. Many countries have started regulation of building materials that
contain radiation such as granite, cement and some drywall products. Radon
has been linked to cleft palate birth defects in a Texas study. The health risks
of radon to lung tissue has numerous studies, it is even known which type of cell
takes the most Alpha radiation hits and why.
Gamma radiation given off by radon daughter progeny was once thought less
harmful than the Alpha struck basal lung cells, but once a lung cell is hit by a
Gama ray, as many as 50 neighboring cells might sustain damage due to the so
called Bystander Effect referred to in this study. The study theorizes that
current estimates on homeowner radon cancer rates may be as much as four
times lower than thought previously. This article from a respected journal
mentions a study that found the bystander effect on cells damaged by Alpha
particles as well. The article concludes that there are few other cancer causing
agents that are as well understood as radon.
This Chinese study found that due to some radon detectors not being sensitive
to Thoron, some projected cancer rates due to radon may be underestimated.
This Physicist says that 14% of childhood leukemia cases in the UK are the
result of Radon (5%) and Polonium 210 which is another byproduct of the decay
of Uranium in granite. His estimate is that having even tiny amounts of Radon
exposure increases a child's risks of leukemia by 1 to 1.5% .
This article by the American Academy of Pediatrics says that Polonium 218 and
214 are especially dangerous and concludes that while there were few studies
of childhood cancer and Radon exposure, other studies show that exposure to
low level radiation may affect children more than adults.
Even the studies on Radon have been studied,in this study, 89 Radon studies
were analyzed, the results pooled and the odds of developing cancer given if
you have Radon exposure in your home.
Here are some countries that regulate granite and other slightly radioactive
building materials and what the trigger levels are.
Ra = Radium Th = Thorium 40K = Potassium 40 bq/ kg = Becquerels per kilogram
China set standards on granite countertop materials, banning the export of
lower radiation level granites. They grade granite countertop material into four
grades : A, B, C, and below C. Only grade A can be used inside a home.
Grades B, C, and below C are allowed to be exported or used outside of homes
Finland 300 Ra bq/kg th 200 bq/kg 40K 3000
Latvia Residential interior use or Ra + Th 170 bq/kg 40K 1500 bq/kg
Industrial or exterior use residential ra + Th 250 bq/kg 40 K 2000 bq/kg
Industrial exterior or road use ra + Th 300 bq/kg 40 K 2500 bq/kg
Germany radium 226 levels below 300 Bq/Kg
Luxembourg Th less that 250 Bq/kg radon less than 350 bq/kg
Czech republic action level 150 -200 bq/kg for buildings occupied 1000 hrs or
more advisory level is 80 to 120.
Sweden says less than 200 Bq per cubic meter and gamma 0.5 uSv/h building
materials must be considered in the amount.
Nordic countries radium 300 thorium 200 40K 3000
Israel .5msv radium 150 thorium 185 40 K 3500
Many other countries are conducting studies on Radon, radiation, and granite to
set regulations for granite and other slightly radioactive building materials. This
article from Cornell University specifically mentions granite countertops adding
to the Radon levels in a home. A few stone companies publish radioactive data
on their stones, but it is usually incomplete or hard to understand like this stone
site has posted.
This expert, Zareena Hamza who is currently a senior research fellow at the
Radiology Safety Division of the Indira Gandhi Centre for Atomic Research
(IGCAR), Kalpakkam, says further research on radon, an alpha-emitting
radioactive gas capable of causing lung cancer, is needed.
But Zareena does not hide her concerns about the use of granite in closed
environs. Radon is found in granite. Will you use granite for your home?
"Never," she says. However, she says granite will not cause harm in places with
The United States recommended action level is 150 Bq per cubic meter (about 4
pCi/l) , giving you about 1.5% increased cancer rate. Even at that low rate, it is
far greater than risks allowed from other carcinogens that mostly are regulated
when they hit 1 in 10,000 and even 1 in 100,000. The only reason given for
allowing 200 to 2000 times the cancer increase rate is that it is nearly impossible
to reduce household Radon levels below 1 pCi/L or .037 Bq. At 0.4 pCi/l, one
non smoking person in a thousand will develop lung cancer, for smokers, .4
pCi/L (0.0148 Bq/L) will kill 3 additional people.
This study showed that Radon daughter products can contaminate the human
body and found that women were 2 to 3 times more contaminated. The study
actually scanned the home occupants bodies, counting as many as 200
radiation events per minute in some subjects. It showed that non smoking
women were at a higher risk than men that smoked. Another of their
conclusions is that Radon risks may have been oversimplified.
Despite the controversies, there are enough facts available to cause concern
when using granite inside a home. With this in mind, it makes little sense to add
even a small amount of Radon from a granite countertop to a families exposure.
PAGE TWO of Radon Info