What does the information on the Radioactivity in countertops mean?

Since you have actual radiation emanation data, I will answer this question directly, but for some back ground information on the link between Radiation from Granites and Quartz and Cancer, please see the question titled “Should I be concerned about the radiation that quartz countertops emit?” which I answered previously.

To help you understand what these numbers mean, let us give you some definitions:  226 Ra =6.7Bq/Kg, 232Th = 3.7 Bq/Kg, 40K = 4.6 +/- 2.7 Bq/Kg are three different measures and for clarity, should be arranged like this:

226 Ra =6.7Bq/Kg,

232Th = 3.7 Bq/Kg,
40K = 4.6 +/- 2.7 Bq/Kg

The first number/letter combination refers to the radioactive element(the number) and the molecular weight of that element. So 226Ra is Radium with a molecular weight of 226 grams/mol(6.02 x 1023 atoms of this element).  232 Thalium and 40 Potasium are also radioactive elements.  Now the information you have here is actually really great because the manufacturer is giving you not only the Radium number(radium is a radioactive breakdown product of Uranium and a precursor to radioactive decay into Radon), but also that of Thalium and potassium, two other radioactive elements that are not commonly referred to as radioactive concerns in granites and countertop materials.

Here is the upshot: without getting into long calculations that involve the size of your countertop, the size of your house, how well your house is ventilated, whether you lay on your countertop or just work around it, etc. you can be sure that the amount of all of the radioactivity emitted by all the elements referenced here would not be a significant threat to your families health.

Here are some relative numbers to help you ease your mind:

1)      You would have to eat your entire 400 lb countertop to equal 75% of the radiation your body gets from radioactive elements that are already inside your body.  This does not include the radiation that you get from the sun and other exterior sources.

2)      If all of the radiation were suddenly to turn into radon based radiation exposure(ie- airborne, it would equal 6.5% of your daily exposure level If your house were airtight.  Fortunately, much of this radioactivity is blocked by the cabinets and the granite or quartz material itself and only 40% of it is radium/radon based radiation, which mixes with the air and gets diluted out anyway.

With that all said, I again refer you to the question titled “Should I be concerned about the radiation that quartz countertops emit?” that was answered recently,  so that you can make your own informed decision about what you define as acceptable risk for radiation exposure.

Best of luck,

This entry was posted in Green Building Questions, Indoor Air Quality, Uncategorized. Bookmark the permalink.

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