Jerry,
That MIA article is highly suspect. They have a history of hiring a "study" done, without insisting that the work be sujected to peer review and publication, two marks of a truly scientific study.

The testing that Dr. Chyi did was okay according to experts in the field, indeed he found that Crema Bordeaux emitted like 292 times more Radon than some of the others! Where this effort went wrong was in the conclusions.

To start with, they used a 13' x 2' granite countertop as the example home, a 2,000 square foot home. Then to make it seem more reasonable, they doubled the square footage by counting top and bottom square footage, bringing it up to 54 square feet. I missed it the first time I read it, had to go back after a nagging feeling that the levels emitted were low.

I can tell you that the average countertop in a home of that size would be between 65 and 75 square feet, so if Chyi said to count both sides since both sides emit the Radon (ignore the edges for now, but they emit as well), that 54 square feet becomes between 130 and 150 for the kitchen alone. Triple his emission from .27 to .81 pCi/Liter. Four picoCuries per Liter have a lung cancer rate of 7 per 1,000 exposed(adults only), according to the EPA, and the relationship is linear, so .81 pCi/L will cause 1.41 cancers per thousand exposed, hardly a small risk factor. Children have 10 times that risk factor according to the NRC and the EPA.

Still serveral problems remain with this conclusion.

First off, There will be far more granite in some homes. Our average granite jobs in a home that size is two slabs, 100 to 120 square feet in the kitchen tops in some cases alone. Add the granite tile flooring, the vanity tops, sometimes shower tiles and you can have a lot more total square footage that would add to the Radon levels in the home. We commonly put three slabs in homes of 2,000 square feet.

Secondly, they are assuming that Crema Bordeaux is the highest radioactive level granite, far from it. Crema Bordeaux is pretty mild stuff, around 20 to 25 uR/hr Gamma emission (Gamma emission is an indicator of the Radon emission, roughly the same). Other granites like Jupanara Bordeaux (shorted to Bordeaux), Shivakaski, Niagara Gold, Four Seasons, Bariacotto, Savanah, and many other granites are far higher. The highest level slab found so far is Savanah, which had hot spots at 1030 uR/hr! I have personally measured 800 uR/hr and higher, plenty of 500 and 400 uR/hr granites slabs around.

So, the second point it that the Crema Bordeaux at 25 uR/hr is very low, 41 times less than the highest level slab found to date. That .27 pCi/L becomes 11 pCi/L when using Savanah. Shivakaski with very high levels has been found in two homes, both failed a Radon test till the granite was removed! The Houston home in the story returned to normal levels after the granite was removed.

Thirdly, that 292 pCi/L that the Crema Bordeaux emitted would eventually spread out all over the home, but what about a homeowner using the kitchen countertop? They are breathing concentrated levels, up to 292 pCi/L according to Dr. CHyi, all the while they are standing near the top. The kitchen, as in the Houstone example, will be far higher Radon level as well. In the Houston case, there was no concern in other areas of the home. The Radon didn't spread out as expected.

In the conculsions, they mention air exchange, up to 6 total changes per hour. Not many homes are in areas where that kind of air exchange can be affordable. Here in Oklahoma, we open the windows rarely, either too hot, too cold, or too many mosquitos. The point is, who ever wrote that section of the article (it wasn't Dr. Chyi), used a massive air exchange rate to further minimalize the risk.

In the end, the granite that we sell, we test before purchase. Some gets rejected, anything over the UN levels of 41 uR/hr. Every slab yard will have multiple slabs of granite way over this level, usually one very, very hot slab, up above 100 uR/hr Gamma. So despite the MIA's article on this issue, there is some concern in the industry. One of our vendors is helping the testing effort, supplying hot granite for testing, and the guy has canceled orders of incoming material that we found to be hot, as well as canceling sold orders of hot material we found in his inventory.

So far, three granite countertops have been removed after being found to raise kitchen Radon levels over 14 pCi/Liter. Then again, hardly anyone knows to look for this problem, and if the MIA has its way, it will stay that way.... The Houston countertop in the story had a previous homeowner develop a brain tumor while living in the home. Dr. Llope, the nuclear Physicst in the TV report, was very skeptical at first. Now he is using his Lab to test granite samples in his free time and speaking out about the radiation levels that a granite countertop can emitt.

I have a blog started about this issue if anyone is interested,

solidsurfacealliance.org Blog » Granite Radiation

And on Youtube.com, we have some short videos of a radiation meter shrieking its little guts out from the Gamma radiation coming from a granite slab. YouTube - TCSRock78's Channel

Brand new meters, calibrated to military specs by an expert.

Heads up guys, we sell granite and it can be a concern. I lost a $10,000 granite job last month because the material was too hot to fabricate. One of my competitors has fewer scruples.

Thanks,
Al