According to a study, Granite countertops may pose a health risk by emitting radioactive gas which can cause cancer. The unpublished study was reported in the New York Times. Rice University physics Professor W.J. Llope asserted that granite countertops, a popular staple in the homes of many people in the U.S. and abroad, give out dangerous radon fumes and gamma radiation, due to their uranium content. He stated that while many stones out of the more than a thousand varieties of granite sold in the United States are not radioactive, but a few really are and none of them is routinely tested for radioactivity.