Do my granite counters emit dangerous levels of radon?

Recently I have heard this question from at least 2 clients for whom we installed granite counters. Following a story published by The New York Times in July 2008, consumers started to question whether they made a mistake by choosing granite for their homes. They had frightening images of the Three-Mile Kitchen island. The reports were about granite counters that contained radium which can emit radon, a radioactive gas that can cause lung cancer.
While some granite counters have been found to give off trace amounts of radon, very few granite countertops pose a real threat. The EPA has even issued a statement saying that there is insufficient evidence to suggest that granite countertops are a source of radon. EPA lists a safety limit of 4 picocuries per liter of air so if you are worried, pick up a home testing kit for about $25. If you see levels above the EPA's limit, call in a specialist.

I have included a few web links that explain this topic in more detail.

http://safegranite.blogspot.com/
http://www.khou.com/images/0805/trifoldradonbrochure_080507.pdf
http://www.marble-institute.com/
http://www.marble-institute.com/industryresources/radontesting_u-akron2008.pdf
http://www.marble-institute.com/industryresources/assessingexposureexecutivesummary.pdf
http://www.reuters.com/article/pressRelease/idUS179560+11-Aug-2008+PRN20080811