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Is My Granite Countertop Radioactive?

Granite countertops have been in the news lately, due to concerns about some of them being radioactive. Here are some questions we have been receiving lately:

Is my granite countertop radioactive?
Yes, all granite countertops are radioactive, however, the level is probably quite low. Different countertops produce different amounts of radiation, depending on their mineral content.

Is my granite countertop safe?
It most likely is, but you can only know by testing it as well as the air in your home.

How can I be sure?
You can measure the radiation level produced by your granite countertop using a radiation detector, such as our GM-10 and GM-45 detectors.

To test the air in your home for radon, you need to have a test done. We don't sell radon test kits, but you can buy from from most home improvement stores for about $20, or you can have a professional perform the test.

Science Content Follows:

Granite often contains radioactive materials such as uranium, thorium, and potassium. These materials do emit radiation. In addition, the uranium produces radium as well as radon, both of which are also radioactive, which can then escape into the air. High levels of radon have been associated with an increase in lung cancer.

The amount of radiation produced depends on the of quantity of radioactive materials present, which varies based on where the granite was mined. Much of the granite is extremely low in these materials, but a few are extremely high. According to a study performed by Rice University physics professor W.J. Llope, some could expose homeowners to the 100 millirem annual limit for radiation (set by the US Department of Energy) in only a few months.

The only way to determine whether or not a particular granite countertop is highly radioactive is to use a radiation detector, such as our GM-10 or GM-45 model detectors. These detectors plug into a computer, such as a laptop, to operate. They continously measure the detected radiation level, displaying it on a graph. This value can then be compared to the readings obtained in other areas of the house (or even outside) to determine the additional amount of radiation produced by the countertop.

Radiation levels vary depending on your location, due to naturally occuring radioactive minerals in the soil, as well as your elevation (higher elevations have higher radiation levels, due to a less thin atmosphere to block cosmic radiation from space).

Thinking of buying a surplus CDV-700 or 715 detector? Be sure to read our report first.