1:5:10:365 EcoTip Blog

November 29, 2008

:334 Radioactive Materials

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1:5:10:334 EcoTip: Radioactive uranium is sometimes present in rock used for construction. This is more likely when the rocks contain granite, phosphate, pitch-blend or shale. Radioactive aggregate has also been mixed with concrete for foundations. Radon test kits and monitors can be used to determine if radon releasing materials are about to be used in new construction or if they are present in existing buildings.

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 Additional Information:

Suggested Review: :128, :129, :130

The following recounts an experience I had almost two decades ago when inspecting a home a family wanted to purchase. I conducted radon testing with electronic monitors, and found radon levels in the guest bedroom of about 27 picocuries per liter of air (EPA’s action level is 4.0 picocuries). The following excerpt is from Prescriptions for a Healthy House which I co-authored and is now in its third edition:

Upon visual examination of the guest bedroom, it was noted that the headboards for the two beds were made of rock that appeared to be granite. The headboards were later tested with a small Geiger counter. While normal radioactive background levels away from the headboards were approximately 12 radioactive counts per minute, the counts close to the headboards were over 300. It was clear that the headboards were at least one source of radon in the room. The headboards were in fact a decorative granite rock imported from Italy. Each headboard weighed several hundred pounds. The floors and walls had been especially constructed to hold the extra weight. It took six strong men to remove each of the headboards to a detached garage. The radon tests were repeated throughout the home with all values now under 1.0 picocurie. The home was given a radon clearance, contingent upon the proper disposal of the headboards.

This was the first home I ever inspected in which a radon source was caused by a building material or furnishing. Although radon from the soil is the most common cause of elevated radiation levels in a home, there are many other possible sources. Since granite rock is sometimes high in uranium, it must be considered a potential source of radon when used in construction. Rock can be a superb building material, but it should always be tested prior to use for the rare possibility of radiation.

Most U.S. manufacturers of granite rock products are now aware of this problem – but it never hurts to double check. Probably the easiest way for occupants to test stone is to set up a radon test kit or monitor in the room with the stone.

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