Study: Silica Rule May Cut Cancer Rate
The U.S. government’s controversial plan to reduce silica exposure on the job has gained fresh support from a new cancer study that says the changes could save lives.
Millions of American workers, including abrasive blasters and construction laborers, could benefit from the proposed rule, concludes the study, published by the American Cancer Society.
The health benefits of lower permissible exposure limits on silica in the workplace are one of several key developments highlighted in "Silica: A Lung Carcinogen," newly published in the society's CA: A Cancer Journal for Clinicians.
"New studies have also shown that excess lung mortality occurs in silica-exposed workers who do not have silicosis and who do not smoke," says the article, by Kyle Steenland, PhD, and Elizabeth Ward, PhD.
Steenland is with the Department of Environmental and Occupational Health at Emory University's Rollins School of Public Health; Ward is national vice president, intramual research, for the American Cancer Society.
Saving Lives
The article reports that the Occupational Safety and Health Administration's Proposed Rule on Occupational Exposure to Respirable Crystalline Silica would drastically reduce deaths from silicosis and lung cancer.
The American Cancer Society, while not directly endorsing the OSHA plan, has publicized Steenland's findings about its benefits.
OSHA's dual proposal—with one standard for general industry and maritime employment and one for construction—was announced in August and published Sept. 12 in the Federal Register.
The proposal would be felt throughout the coating, construction and abrasive blasting industries. Workers are exposed to airborne respirable silica dust particles through cutting, sawing, drilling and crushing of concrete, brick, block and other stone products and in operations using sand products.
Abrasive blasters are among the occupations at highest risk, Steenland's article says.
OSHA has extended the 90-day public comment period on the proposal through Jan. 27, 2014.
The Construction Industry Safety Coalition, comprised of 18 employer associations, organized this fall in opposition to the plan, calling it costly and burdensome. Worker health advocates and labor unions strongly support the rule.
Halving the Death Rate
OSHA, which has issued health warnings about silica since the 1930s, says that the lower limits will, when fully implemented, save 700 lives and prevent 1,600 cases of silicosis each year. The silica standard has not been updated since 1971.
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| Steenland and Ward |
Steenland's article says the new limits will slash the death rate among the approximately 2.2 million workers now exposed to silica—most of them in construction-related industries. Cancer may develop years after silica exposure occurs, the article notes.
"Silica has been known to cause silicosis for centuries, and evidence that silica causes lung cancer has accusmulated over the last several decades," the article says.
"Risk assessments estimate 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."
By the Numbers
The U.S. death rate from silicosis has decreased from about 1,200 annually in 1968 to fewer than 100 annually now, the report says, citing figures from the National Institute of Occupational Safety and Health (NIOSH). However, it adds, there is no national surveillance system for silicosis, and reports by various states and hospitals vary widely and are probably underreported.
State data suggest between 3,600 and 7,300 new cases of silicosis annually, while hospital data estimate 1,000 discharges for the disease annually and another 1,000 discharges for pneumoconiosis (of which the most common is silicosis), the report says.
Meanwhile, it says, there have been more than 100 epidemiologic studies of silica and lung cancer—due to the widespread occupational exposure and to the issue's "public health importance."
Controlling Exposure
The report says that reducing silica exposure, not increasing workers' protective equipment, is the "best approach to primary prevention" in "high-exposure situations."
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| NJ Department of Health and Senior Services / Silicosis Surveillance Project |
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Simple controls, such as wetting down dust, can reduce silica exposure. The connection between silica and lung cancer has been the subject of more than 100 epidemiological studies. |
"Respirators may be useful for workers in short-term high-exposure situations, but are generally not recommended as the primary means of exposure control due to worker discomfort, difficulties in communicating with others, lack of compliance and enforcement, and the fitting and maintenance requirements," the authors say.
The authors conclude that "there is strong and consistent evidence that silica exposure increases lung cancer risk."
"This has both regulatory implications and implications for clinicians," they add.
"For OSHA, it is appropriate to lower existing standards."
