Craftsmen who cut granite for kitchen countertops can be at risk of radiation exposure thousands of times above the federal safety limit, according to new research The danger results from inhaling the airborne granite dust, which sometimes contains significant quantities of uranium and other dangerous isotopes, scientists say. "What we found scared the daylights out of us," said co-author Linda Kincaid, an industrial hygienist in Saratoga, Calif. The study, "Implications of Granite Counter Top Construction and Uses," raises concerns that the stone dust could be exposing America's estimated 24,000 granite fabricators to elevated cancer risks, according to Kincaid. People living in homes with granite countertops face no health concerns from the dust, which is generated when the stone is cut At issue is the potential threat to workers who process granite. Kincaid and co-authors Al Gerhart, an Oklahoma City stonecutter, and Dave Bernhardt, a Salt Lake City health physicist, contend that when workers cut slabs of stone, they sometimes release radioactive dust into the air. In turn, that dust is inhaled, reaching the workers' lungs. The contaminated dust bombards the lungs with so called alpha particles -- a particularly damaging form of radiation, according to Kincaid, who said lung tissue is especially vulnerable. "It's very delicate, very fragile, very easily damaged," she said. While public health officials have for decades focused on the elevated risk of respiratory diseases for those working in dusty conditions, the study unveiled at the Health Physics Society's annual meeting July 13 in Minneapolis is the first look at how a granite byproduct could be harming workers The Marble Institute of America, a leading trade group for stone industry, slammed the new research. "This report has no scientific credibility and cannot be relied upon," said Jim Hieb, vice president of the Marble Institute, which is based in Cleveland. Ohio But, responding to the findings, a spokeswoman for the U.S. Department of Labor called for more research .