I haven't read this post, I just don't have time. Here is an article that I wrote on the subject, hope it helps.
Is My Granite Counter Top Dangerous?
Recently a trade association for the solid surface counter top manufacturers formed and funded a not for profit association to test and disseminate information about granite as used in homes. They produced videos and press releases stating that granite used in counter tops and floors is radioactive and a radon emitter. As you can imagine it got the attention of thousands of home owners and now they don't know what to do.
At this point there are no accepted protocols to test and interpret the data. There are several groups and Universities work to prove test methods. The data that I have seen indicates that most of the species of stone contribute very little radon to the indoor and are of no concern. The key word is "most".
If I just spent thousands of dollars on granite counter top and floors in my home I would want to know for sure if it was dangerous. So what do we as home inspectors do?
The main concern is radon, so testing may be conducted using a minimum of 3 tests. One in the lowest area of the home, one at least 20 inches above the stone product and one in a completely different room on the same level as the stone product. The test placement and house conditions should follow normal protocols for the device used. As I mentioned above there is no consensus for a method to test so the client must be informed of that fact.
Interpretation of gathered data is the key to determining the risk. Since there is no consensus, it is essential that a qualified radiation professional interpret the test results. Most states have such individuals in the radiation protection section of the health department or environmental protection department. They should be consulted and quoted in any report to the consumer.
Bruce Thomas
9/12/08
