The results of a newly completed study spearheaded by the Marble Institute of America (MIA) indicate that radon emissions from granite countertops are far below levels considered to pose a human health risk. Consumer concern about the potential for harmful levels of radon emissions from granite countertops spread in July 2008, spurring the MIA to develop a set of standards for testing radon emissions from granite materials.
Environmental Health & Engineering, the independent laboratory that conducted the study, performed more than 400 tests on 115 different varieties of granite, including types that make up 80 percent of sales for countertop applications in the United States. The study, “Assessing Exposure to Radon and Radiation from Granite Countertops,” found that no stone slab among those it sampled contributed to radon levels that reach even average outdoor radon concentrations of 0.4 picocuries per liter of air (pCi/L). The U.S. Environmental Protection Agency’s recommended actionable level is 4 pCi/L.
Stones found to have the lowest levels of radon emissions also exhibited little variability in radon concentrations from slab to slab; they also account for the vast majority of granite countertop sales. Moreover, the granite slabs that were found to emit radon at higher levels were still well below average outdoor concentrations and also comprise less than 1 percent of granite sales in the U.S.
John F. McCarthy, president of Environmental Health & Engineering, says the testing procedures were designed to assess potential radon exposure and risk in real-world conditions, to ensure the testing results represent scenarios that will actually be encountered in the home. The study is being submitted to a scientific journal for peer review.
“This study once again proves that granite countertops do not pose the risk that some exaggerated media reports would suggest,” said MIA’s president, Guido Gliori, in a statement announcing the findings.
To download the executive summary of “Assessing Exposure to Radon and Radiation from Granite Countertops,” click here. Also, read our Aug. 7, 2008, and July 24, 2008, blog posts about the radon-emitting granite scare.
