Although most of the media’s attention on whether or not granite counter surfaces are a health risk has quieted down, there is always a lingering question with this issue. As a home inspector, I routinely perform radon tests in homes and have also tested on granite personally. I have not found readings that would be alarming …. as matter of fact, radon is commonly present in most northeast Ohio homes BELOW ground level. According to government EPA “…since granite is generally not very porous, less radon is likely to escape from it than from a more porous stone such as sandstone. It’s important to know that radon originating in the soil beneath homes is a more common problem and a far larger public health risk than radon from granite building materials. Also, any radon from granite countertops in kitchens or bathrooms is likely to be diluted in the typical home since those rooms are usually well ventilated.” http://www.epa.gov/radiation/tenorm/granite-countertops.html
To reduce the risk of lung cancer from exposure to radon, which is a known carcinogen, you should test the air in your home. Although there are home testing kits, a trained radon specialist with knowledge on calibration and interpretation of readings is recommended by the EPA.
There are lots of things that we expose our bodies to everyday … but the beauty and durability of granite countertops far outweighs the minimal radioactivity that occurs naturally in many natural products like granite.