In the recent months, a serious question, whether granite countertops and granite tiles installed in ordinary homes emit radon, has been raised in the stone industry. The public concern actually started last summer when several news media broke a story that a doctor removed her granite after testing high for radiation replaced it with a different granite. When the Marble Institute of America announced recently it will launch a "Home Approved Stone" program to reassure consumers about granite's safety, the degree of attention received in the industry on this hot issue is apparent. Many scientists, including physicists and chemists, have been conducting testing, writing papers and debating their findings to each other on radon emissions of household granites.

Now homeowners have something new to ponder when building new homes or remodeling the existing ones, are harmful radiations and radon gases really emitting from beautiful granite slabs and tiles?



Probably, this will remain to be a debatable topic for quite some time. According to the Marble Institute, its testing yet to find a problem piece of granite. Most who seek testing receive reassuring news that their countertops are safe. When testing does reveal high radon levels, this undesirable gas is usually emanating from the basement, not the kitchen. However, many still insist that the problematic granite stones are being sold and installed and their owners are unaware of a radioactive risk existing with the material.



Are we facing a radiation problem with ordinary granite slabs? It depends who gives answer. Officially, the Environmental Protection Agency declared it had "no reliable data" to conclude that granite was significantly increasing indoor radon levels. Radon coming from the ground is a much bigger concern. But others see greater potential risk. "The vast majority of granites in the vast majority of houses are not going to be a problem," said Daniel Steck, a physics professor and the head of the Minnesota Radon Project at St. John's University in Collegeville, Minn. Steck has tested about 250 granite varieties and suggested that none of those emitted enough radiation to be a concern. A small minority, however, about 5 percent, appeared to contribute enough radon to pose "a mild problem" when used in large quantities or in a small, tightly sealed home.



The more specific debate now is whether those granite stones pose a health risk to human being, if yes in what circumstances, and how to identify the problematic stones. Unfortunately, it is impossible to spot a hot slab by its appearance, color or even its name that is variable in different countries and regions. Granite stones with the same name can have different geological content; and the same granite could have a number of different names. As demands for building granite have been on rapid rise in North America, a huge number of stones are being imported from different parts of the world. Some experts suggest greater scrutiny on the foreign granite stones is needed to ensure safe applications.



"It's an uncontrolled situation," said William Llope, a nuclear physicist at Rice University in Houston, "The majority of granites are quiet," with radiation levels that are negligible when compared with background radiation. But there are now about 2,000 granites being exported from about 70 countries, he noted, with some quarries within miles of uranium mines. "Some stones from Namibia and Brazil are wicked hot." Still, the health risk is ambiguous and probably long-term. "You're not going to spend six months in your kitchen and die of cancer," Llope noted. But extended exposure to the hottest granites he's tested has the potential to increase lifetime cancer risk, especially for young children. "It's a risk people could avoid if they wanted to."



But many professionals in the stone industry believe that any risk associated with the granite slabs is being wildly overblown by those with clear commercial motives. "A Geiger counter makes for great television, but it's not accurate science," argued Guido Gliori, president of the Marble Institute. "It's more complicated than that. You have to determine emanation and how it's diluted by the exchange of air in your home." Gliori pointed out that some of the research linking granite and radiation has been funded by manufacturers of competing countertop materials. "It's a shame they want to trash the stone industry to support synthetic stone. Granite is safe and beautiful."



According to reports, the Marble Institute funded an independent study of over 100 popular granites, including some that have been argued to contain higher radiation by the others. The study did not find a single problem slab.



Although further studies are necessary to conclude the "innocence" of granite in radon radiations, in the mean time, we should be able to argue with confidence that no credible evidences suggest the granite slab has been a major source for elevating indoor radon levels. Even if your home tests high for radon, the likeliest contributor is your soil, not your granite countertop.