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2217. OCCUPATIONAL EXPOSURE TO CRYSTALLINE SILICA
Regulatory Plan: This entry is Seq. No. 74 in Part II of this issue of the Federal Register.
74. OCCUPATIONAL EXPOSURE TO CRYSTALLINE SILICA
Priority: Economically Significant. Major status under 5 USC 801 is undetermined.
Unfunded Mandates: Undetermined
Legal Authority: 29 USC 655(b); 29 USC 657
CFR Citation: 29 CFR 1910; 29 CFR 1926; 29 CFR 1915; 29 CFR 1916; 29 CFR 1917; 29 CFR 1918
Legal Deadline: None
Abstract: Silica exposure remains a serious threat to nearly 2 million U.S. workers, including more that 100,000 workers in high risk jobs such as abrasive blasting, foundry work, stonecutting, rock drilling, quarry work and tunneling. The seriousness of the health hazards associated with silica exposure is demonstrated by the fatalities and disabling illnesses that continue to occur in sandblasters and rock drillers and by recent studies that demonstrate a statistically significant increase in lung cancer among silica- exposed workers. In October 1996, the International Agency for Research on Cancer classified crystalline silica as "carcinogenic to humans." Exposure studies indicate that some workers are still exposed to very high levels of silica. Although OSHA currently has a permissible exposure limit for crystalline silica (10mg/m3 divided by the percent of silica in the dust + 2, respirable), more than 30 percent of OSHA- collected silica samples from 1982 through 1991 exceeded this limit. Additionally, recent studies suggest that the current OSHA standard is insufficient to protect against silicosis. For example, a recent study concluded that a 45-year exposure under the current OSHA standard would lead to a lifetime risk of silicosis of 35 percent to 47 percent. OSHA plans to publish a proposed rule on crystalline silica because the agency has preliminarily concluded that there will be no significant progress in the prevention of silica-related diseases without the adoption of a full and comprehensive silica standard, including provisions for exposure monitoring, engineering and work practice controls, training and education, respiratory protection, and medical surveillance. A comprehensive standard will improve worker protection, ensure adequate prevention programs, and further reduce the incidence of silica-related diseases.
Statement of Need: The current OSHA permissible exposure limit for silica is 10mg/m3 divided by the percent of silica in the dust + 2 (respirable) and 30 mg/m3 divided by the percent of silica in the dust + 2 (total dust). In the interval since this limit was promulgated, there have been a number of studies of workers that have estimated that close to 50 percent of workers exposed to silica at the current limit for a 45-year working lifetime would develop silicosis, a disabling, progressive and sometimes fatal disease involving scarring of the lung, coughing, and shortness of breath. There are currently about 300 deaths reported per year from silicosis. However, the actual number of cases and the true risk is unknown due to inadequate case ascertainment, which means that the number of deaths is probably under-reported. Also, since the promulgation of OSHA's permissible exposure limit studies have demonstrated a statistically significant, dose-related increase in lung cancer in several occupational groups. Because of these recent findings, OSHA believes that it will be necessary to conduct a risk assessment to determine whether the current permissible exposure limit is protective of worker health. OSHA also believes that, in addition to the permissible exposure limit, the ancillary provisions, such as engineering controls, provided by a comprehensive standard will be necessary to reduce worker exposure to crystalline silica.
Summary of the Legal Basis: The legal basis for the proposed rule is a preliminary determination by the Secretary of Labor that exposure to silica at the Agency's current permissible exposure limits poses a significant risk of material impairment of health and that a standard will substantially reduce that risk.
Alternatives: OSHA has considered or conducted several programs designed to reduce worker exposure to crystalline silica. The OSHA Special Emphasis Program for Silicosis provides inspection targeting to reduce or eliminate workplace exposures to crystalline silica. The National Campaign to Eliminate Silicosis being conducted by OSHA (in conjunction with the National Institute for Occupational Safety and Health, the Mine Safety and Health Administration, and the American Lung Association) is an ongoing program involving outreach and education and the dissemination of materials on methods to reduce worker exposure to crystalline silica. Other nonregulatory approaches might include the issuance of nonmandatory guidelines, enforcing lower limits through the "general duty" clause of the OSH Act in cases where substantial evidence exists that exposure presents a recognized hazard of death or serious physical harm, and the issuance of hazard alerts. Although these approaches may be partially effective in reducing worker exposure to crystalline silica and reducing disease risk, OSHA believes that progress in the prevention of silica-related diseases demands the issuance of a comprehensive silica standard.
Anticipated Costs and Benefits: The scope of the proposed rule is currently under development, and thus quantitative estimates of costs and benefits have not been determined at this time.
Risks: OSHA has not yet completed an assessment of the risks of exposure to crystalline silica. Other studies have shown risks ranging from 35 to 47 percent among workers exposed over a working lifetime and have additionally identified silica as a potential occupational carcinogen.
Regulatory Flexibility Analysis Required: Undetermined
Government Levels Affected: Undetermined
Director, Health Standards Programs
Department of Labor
Occupational Safety and Health Administration
200 Constitution Avenue NW.
Room N3718, FP Building
Washington, DC 20210
Phone: 202 219-7075
Fax: 202 219-7125
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