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Statement of Need: The current OSHA permissible exposure limit for silica is 10 mg/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 identification, which means that the number of deaths is probably underreported. 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 Asssociation) 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.