Saturday, August 02, 2008

"Honey-poo, Why Is the Kitchen Glowing?"

Granite countertops were all the rage and the latest brain dead, "must have", keep-up-with-the-Joneses housing accouterment here in Marin (and pretty much everywhere else in bubble markets). Well, it seems that if you are shopping for a trendy Marin house you would be wise to bring your Geiger counter with you.

Thanks to a reader for sending me this link.


marine_explorer said...

From the NYT article, with comments.

The granite, it turned out, contained high levels of uranium, which is not only radioactive but releases radon gas as it decays.

The presence of Uranium is far more troubling. While the public regards Radon as "the" threat, it's actually the decay products which are dangerous and can embed in the lungs. creating long-term cancer risk.

A “hot” granite countertop like Dr. Sugarman’s might add a fraction of a millirem per hour and that is if you were a few inches from it or touching it the entire time.

If that were a completely contained alpha source, that would be one thing—and probably minimal risk. However, since this granite was installed and cut to fit on site, that means U-238 particles are no doubt in the house and already inhaled or ingested by the Dr. and her family.

This is simply inexcusable how a product like this got by what should be an easy test. At some point, someone knew but sold this source anyway. Once again, the media only covers 1/2 the story.

zarkov01 said...

Uranium, which is mostly the U238 isotope (99.27%) is virtually harmless outside your body. With a half life of 4.45 billion years it's not particularly radioactive. Inhaling uranium dust could be harmful if the dust particles were in the size range of 1-10 microns. Larger particles impact the walls of the respiratory tree and get washed out by mucous flow. Particles smaller than 1 micron are so small they behave like a gas and are exhaled. Granite is only about 20 parts per million uranium, so the danger is minimal.

The human body too is internally radioactive, mostly from potassium 40. You will probably get more radiation sleeping with your wife than from your granite counters.

Uranium also self shields, meaning only the atoms near the surface emit into the environment. If ever I heard of a non-problem, radiation from granite counters is it.

I personally prefer Corian for counter tops. But be careful when ordering. A designer told me that some eastern suppliers double or triple the price for orders going to California because they regard the customers there as pretty stupid.

marine_explorer said...

You could be right--I'm just naturally very wary of radioactive substances. Thanks for the info!

zarkov01 said...

marin explorer

You need not be particularly wary because the interaction of ionizing radiation and biological tissue is very well understood except at very low levels where we are uncertain as to whether there are cell repair processes that create a threshold. Compare and contrast to chemicals including drugs-- especially drugs.

Bananas contain potassium 40 a radioactive isotope, which actually produces a hard gamma ray, harder than uranium 238. Hard gammas have more energy and are more damaging to tissue. The point being you can't get away from radiation, it's everywhere. Of course a really hot piece of granite can come along. So if you're the type that worries about rare events, get a kit and test your granite surfaces.

Today I had a talk with a friend who does atomic transport calculations for a living, and he confirmed my calculation of 1 decay per 4 grams of (average) granite and that's not much. The uranium does produce a radon daughter product and it will diffuse through the granite unless the surface sealant is impermeable to radon gas. But radon gas in your kitchen is not much of a problem unless your house is air tight. Radon in a basement tends to collect there which is why we worry about it. But the Bay Area has little in the way of radon hot spots.

Worry more about the coming financial collapse and the degradation of the quality of life here in CA from overcrowding and illegal immigration.

francis said...

As for the real estate market, it's a tale of two things right now as I see it: new listings and rentals. As I mention in my video blog for this month, most areas are starved for new inventory as the market slowly moves towards "neutral" and away from one favoring the buyers. I realize this is in stark contrast to what's going on in the rest of the country and probably in direct contrast to newspaper headlines nationwide, but it's the reality of our highly unusual market here. Good properties at attractive prices continue to sell with multiple offers, despite the 20% decline still seen for many parts of the state. Though the 'B' locations with 'A' prices continue to sit. So what do the buyers do if they can't find the right property? They drive the rental market through the roof.
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