US Dept EPA's findings on Granite Countertops

 

http://www.epa.gov/radiation/tenorm/granite-countertops.html

 

Akron Univeristy's Study of Radon and Granite Countertops

 

http://www.wpbradon.com/EPA%20Papers/Radon%20Mitgation%20Papers/Radon%20Testing%20of%20Various%20Countertop%20Materials%202008.pdf