Meta-analysis: Strong evidence silica increases cancer risk ATLANTA, Jan. 11 (UPI) -- A meta-analysis found strong and consistent evidence that silica exposure increases lung cancer risk, U.S. researchers say. Elizabeth Ward, national vice president of intramural research for the American Cancer Society, and researchers at Emory University in Atlanta said lung cancer is the leading cause of cancer death among U.S. men and women and tobacco smoke is the greatest risk factor. However, exposure to radon, asbestos, silica and air pollution also increases the risk of developing lung cancer. Silica is a mineral found in materials such as sand, stone, rock, concrete and brick used in numerous industries including construction, mining and manufacturing. Workers could be exposed to silica in a variety of ways such as inhaling particles when cutting, sawing, or drilling a product that contains silica. About 2.2 million U.S. workers are exposed to silica particles each year, said the Occupational Safety and Health Administration. Ward and study co-author, Kyle Steenland of the Rollins School of Public Health at Emory said last August, OSHA proposed a new rule that would cut in half the amount of inhalable crystalline silica particles a worker can be exposed to in an 8-hour shift. OSHA estimated the new rule could "save nearly 700 lives and prevent 1,600 new cases of silicosis per year," the researchers said. The researchers suggested in the paper the new regulation was well-supported by scientific evidence. The findings were published in CA: A Cancer Journal for Clinicians.