A new review outlines the health effects of silica, and calls for action to reduce illness and death from silica exposure at work. For centuries, too much silica exposure, such as when workers cut, grind, crush, or drill silica-containing materials such as concrete, masonry, tile, and rock, has been known to cause lung disease (silicosis). Evidence linking silica to lung cancer is more recent. There is some low-level silica exposure on beaches and in ambient air in general but no evidence such low-level exposure causes health effects.
Citing new studies finding that silica-exposed workers who do not have silicosis and who do not smoke still have increased rates of death from lung mortality, they advocate a new rule lowering the permissible occupational exposure for the estimated 2.2 million US workers currently exposed to silica. Estimates are that lowering occupational exposure limits from the current to the proposed standard will reduce silicosis and lung cancer mortality to approximately one-half of the rates predicted under the current standard.
The most effective measures for the control of occupational silica exposures include banning sandblasting, substituting metal grits for abrasive blasting, modifying processes and equipment, and controlling dust transmission by using enclosures, air curtains, water spray, and ventilation techniques, and the use of personal protective equipment.
“Current regulations have substantially reduced silicosis death rates in the United States, but new cases of silicosis continue to be diagnosed,” says Steenland. “And while the lung cancer risk associated with silica exposure is not as large as some other lung carcinogens, like smoking or asbestos exposure, there is strong and consistent evidence that silica exposure increases lung cancer risk.”