Answer to Question #7834 Submitted to "Ask the Experts"
The following question was answered by an expert in the appropriate field:
You are not alone in your concerns about the health hazards of granite countertops. Since The New York Times ran an article on this issue in July 2008, we've received many similar questions.
In response to these concerns, the American Association of Radon Scientists and Technologists has prepared a position statement that discusses the risk from radon. The statement notes that the U.S. Environmental Protection Agency (EPA) does not believe that there is evidence that granite countertops significantly increase indoor radon levels. You can read more about the risks of radon at the EPA's Web site.
Another response to these concerns was issued by the Health Physics Society. This document discusses the differences between measuring for radon and measuring for gamma radiation on the countertop surface. It includes much technical discussion, but the bottom line is "no action needs to be taken to remove granite countertops in existing homes. If there are concerns by the homeowners, appropriate radon concentration monitoring should be conducted in living areas of the home (per EPA protocols). If the granite countertop is determined to be a cause for concern, the most risk-reducing and cost-effective action to take would be to remove radon from the air throughout the home rather than remove the granite countertop."
This is consistent with the EPA's position that the most significant source of radon in homes is from gas in the soil that is drawn indoors. Uranium in the soil produces radon gas, and the gas moves up into homes through cracks and other holes in the foundation. Homes can trap radon inside, where it builds up. The EPA and the Surgeon General recommend testing all homes below the third floor for radon.
Unlike radon testing, measurements of gamma radiation from the granite will not provide you with useful information about health hazards. Gamma radiation measurements simply provide an exposure rate at the countertop surface, which is difficult to translate into a meaningful measure of health hazard to humans. They do not tell you about the average radiation dose to occupants of the home.
Given your concerns about potential health hazards in your daughter and son-in-law's home, you have done the most appropriate thing by contacting a laboratory to do radon testing in the home. The radon measurements they make will tell you if there is any health hazard from the granite countertops or other possible sources of radon in the home.
I hope this helps resolve your concerns.
Environmental Health Physicist