Radiation exposure could occur when radioactive materials such as uranium, thorium, potassium and any of their decay products, such as radium and radon are released into the environment. Radon is a naturally occurring radioactive gas, is found in igneous rock and soil, and well water. It moves up through the ground to the air and into your home through cracks and other holes in the foundation.
Radon emits alpha radiation; it is a cancer-causing radioactive gas. Radon breaks down into solid radioactive elements called radon progeny that attach to dust and other particles we breath into our lungs, giving off radiation that can damage the DNA inside the body’s cells. You cannot see, smell or taste radon.
Radon is everywhere, the US Environmental Protection Agency (EPA), estimates that nearly 1 out of every 15 homes in the United States has elevated radon levels. You can check radon levels in your home with a do-it-yourself radon detection kit that can be ordered through the mail http://www.fcs.uga.edu/extension/radon_test, bought in an UGA Extension office or in hardware or home supply stores. The kit is placed in the home for three or four days and then mailed to a lab for analysis. People should take action to lower radon levels in their home if the level is 4.0 pCi/L or higher.
A granite countertop in a home would not increase the radiation level above the normal according to the EPA. Levels of radon may be found in water that comes from deep, underground wells in rock. The University of Georgia Extension can test for the radionuclides—uranium and radon—in your drinking water. Contact your local County Extension office (1-800-ASK-UGA1) for details on sampling and submission.