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High Radon and Radiation from some granite counters
Re: High Radon and Radiation from some granite counters
Hello,
http://solidsurfacealliance.org/blog/wp-admin/edit.php
I am the evil genius (Ha!) behind the SSA site on the granite/Radon/radiation issues. A granite fabricator by the way, along with other products we work with.
Dr. Llope has been a huge help in this effort to prove the existence of significant Radiation emmisions from some granites used as countertop and floor tile. Plenty of Radon experts helping as well, Stan Liebert, Bill Brodhead, of course William Levy has recently joined the effort, or shall I say we have joined him since he has been working on the issue of Radon from building materials for close to two decades.
Radiation levels are indicitive of Radon emissions, from 20% to 95% depending upon which study you read, which in turn depends on which stones were in the study.
Dr. Kitto reviewed around 40 samples recently, has sent his study for peer review (Health Physics Journal if I remember right). He found one or two granite top materials that would contribute 1 pCi/L and one that would contribute up to 2 pCi/L. Bill Brodhead is one of his confidants in the effort, and two of the samples I sent Brodhead measured 50 pCi/SF/Hr and 500 pCi/SF/Hr. It would seem that finding these levels has shown the need to revisit the issue with another study. I know that Brodhead recently shipped the samples to Dr. Kitto and I will send Kitto some others as well.
Dr. Steck, who has done previous work for the MIA (who opposes this effort to prove hot granite) has also received samples far hotter than he has seen in the past.
Here is the thing, all of us know that we make our decisions based on what we know at the time. New info will always change a reasonable mind. Skepticism is good, but apply that same skepticism to what the MIA is saying. In the end, the results of the tests will prove it one way or the other.
Liebert has found several cases of hot granite raising Radon levels, and proof will soon be published, including homeowner interveiws. The company that sold the stone, Innovative Stone of Long Island NY, appears to have changed the name of the stone since it has received a bad reputation in the stone industry. A relatively cheap stone, it was popular, but several shops have stopped selling it, including one huge national seller of natural stone and quartz.
In addition to the Houston TV report case (I sent William a copy of the lab report on that stone, 1,100 times normal Radium content), there are more cases popping up from the Houston in home countertop testing effort. About 200 homes tested so far, 100 more to go before the survey ends.
Dr. Llope and I stay in touch, and I've already addressed the issues in his post, but I thought it would be a good way to introduce some of the salient points here.
“Twenty microRems per hour is written as 20uR/hr. "
Absolutely, the quality factor for internal contamination is a major factor, thus the need to write as Roentgen instead of Rem. However, to avoid confusing readers with no background in the units used, I tend to us Roentgen as interchangable with Rem, which you point out can be interchangable in our limited use.
For a fabricator, who is subjected to inhaling small quanities of the radioactive dust, ingestion of the radioactive dust from touching the face or not washing their hands before lunch, any manner of pathways into the digestive system, we certainly would write as Roentgens. Then we would also measure the Alpha and Beta radiation, add that to the Gamma for the total exposure to the fabrictor.
Dr Hans Henson is a shill hired by the MIA. Has a PhD in geology, from Australia, and has been quoted by his friends as being hired to "dirt up" the Quartz industry. While no fan of Quartz (but I do sell it when I have to), I dislike a hired gun lying for a buck. Dr. Hans refused to answer questions posed to him on a consumer forum where he was attacking Dr. Llopes investigation into this issue.
The EPA is actively investigating the issue. I spoke to the regional head a few weeks ago while in the office of our state Radiation dept. The Radiation dept manager was defending our granite countertop radiation measurements to the EPA regional head, who had been given the task of verifying our reports. Since then, the state Radiation dept has shown to be very interested, including setting an appointment with a homeowner whose granite top had alarming rates of Gamma radiation.
Our meters were found to be withing accuracy ranges normal for hand held meters, within 25% of the Radiation departments more expensive and more accurate meter. Experts like Dr. Llope predict that even these more accurate and more expensive meters may miss from two to six times more radiation than his very accurate Gamma Spectrometer set up.
I ordered my Gamma Spectrometer last week, once the learning curve is past, I'll post some results on the SSA blog site.
If Inspectors begin measuring granite counters, showers, or tile, you will find that existing hand held meters will seldom agree with another, even of the same brand and model. They have different "efficiencies" as Dr. Llope pointed out, so using one to sort high level granite from low level granite is workable, just don't fool yourself into thinking you are getting an accurate reading.
Depending upon the radiation strength and type, you might read 11% of the radiation or 65% of the radiation and you might over count the Alpha if it is a strong Alpha source.
For that reason, we are measuring primarily Gamma when surveying granite countertop materials. Our meters are specified at 30% one way or the other, within a range of electron volt levels. Under the range won't be counted, over the range will blast right through the meter without registering.
No doubt by now readers are realizing that this will not be an exact science with hand held detectors, but the meters are accurate to sort high from low, thus are useful and accurate enough for this use. The "safe" level MUST be low enough to account for the innaccuracies in measuring, luckily every granite tested so far has low level slabs available if the fabricator, vendor, and quarry selling the product will take the care to test. The estimate of problem slabs runs from 3% to 10%, but the Chinese report that from 20% to 30% fail their Class A "safe" standard test.
The remediation info from the Federal goverment is here
Incidently, I don't consider myself an expert in Radon emmisson from natural stone, more like a some what educated advocate of the issue. William and the other Radon techs, Dr. Kitto, Dr. Steck and Dr. Llope are far more prepared to answer questions or comments. I do seem to have developed enough experience in measuring radiation from natural stones to be of some use to the experts, that and my access to samples. I can probably answer questions on the radiation issues of granite.
But, bottom line, heads up, this is a real issue. A huge story on this ought to be published late next week in a national newspaper. I will provide a link as soon as it is printed. It was slated for last week, but when the editors realized the depth and importance of the article, they personally interviewed some of the top sources and then sent photographers to document two of the labs helping out.
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Last edited by Al Gerhart : Yesterday at 08:21 PM.
Please take the time to review the recent findings posted Web home: Radiation & Radon from Natural Stone, W.J. Llope by Web Home: Radiation and Radon from Natural Stone
W.J. Llope
Rice University, Houston, TX
and review : solidsurfacealliance.org Blog › Login
Here is a recent post reply:
W.J. Llope said,
June 11, 2008 at 8:06 am
Hi -
thanks for the update. but there’s a couple of things here that you might want to correct….
“Dr. Hans Hensen claims that most of the radiation in granite countertops comes from Potassium 40 ( K 40), in fact most of the radiation comes from Radon and Thorium.”
from the stones i’ve looked at the Uranium ore is the major player. i see less than
a 1% contribution from 40-K. the longer-lived Radon (the one people mean
they say “radon”, half life ~4 days) is in the 238-U series. the 232-Th series also produces a “radon” called “thoron” but that guy has a very short half-life.
“So there it is, even the EPA says that the radiation risks are unknown…… ”
not a mistake in your post - just wanted to mention that i intend to change
this. i have now ~40 samples from 3 stone yards and several private
individuals that i will investigate with my NaI(Th) spectrometer.
i intend to publish. Journal of Environmental Radioactivity or something
like that.
“Twenty microRems per hour is written as 20uR/hr. ”
20 uR/hr is 20 micro-Roentgens per hour, not 20 micro-rem/hr.
the latter (rem) is the unit of absorbed dose. it is the product of the dose
(in Roentgens) and a “quality factor”. this quality factor accounts for
the different amount of damage (”biological efficiency”) that different particles can do to human tissue.
the quality factor for gammas and betas is one, and it’s 20 for alphas.
in the sense that *external* alpha radiation generally poses little risk
(typical 1-2 MeV alphas have a range of only 1-2″ in air, and less than
the thickness of a single piece of paper, and they
are absorbed in the dead-layer of skin called the epidermis) then it’s not
heinous to mix mR and mrem. but your geiger counters are measuring
mR, not mrem, because they do not and cannot know what the particles
are.
my gamma spectrometer does though! also, your geiger counters are
generally underestimating the true fluence, especially for energies above
1 MeV, due to their known (in)efficiency as a function of the particle and
energy. this too is something that i can correct for with my NaI setup
to get the “true” fluence…
BTW the use of the unit “rem” is not strongly discouraged by NIST, although
when i undergo my yearly radiation retraining as part of my day job, the
unit mrem is still used. and it is very common elsewhere.
“Without going into a lot of detail on this topic, EPA and some State agencies have used an exposure of 20 microR/hour as a remediation action level for entire rooms, homes or buildings.”
i’d love to have references for that comment!
Re: High Radon and Radiation from some granite counters
the pdf of the paper Dr Llope is at :
http://www.khou.com/images/0805/LLOP...dRn_080507.pdf
William Levy
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