Study Recommends Change to Proposed OSHA Crystalline Silica Dust PEL

OSHA's Notice of Proposed Rulemaking (NPRM) for Occupational Exposure to Respirable Crystalline Silica was published in the Federal Register on September 12, 2013.  Although this is a proposal, it is not a final rule. OSHA encourages the public to participate in development of the rule by submitting comments and participating in public hearings. Your input will help OSHA develop a rule that ensures healthy working conditions for affected employees and is feasible for employers.

Inhalation of very small (respirable) crystalline silica dust particles puts workers at risk for silicosis, lung cancer, chronic obstructive pulmonary disease (COPD), and kidney disease. OSHA estimates that the proposed rule will save nearly 700 lives and prevent 1,600 new cases of silicosis per year, once the full effects of the rule are realized.  About 2.2 million workers are exposed to respirable crystalline silica dust in their workplaces. The majority of these workers, about 1.85 million, are in the construction industry.  Exposures occur when workers cut, grind, crush, or drill silica-containing materials such as concrete, masonry, tile, and rock. About 320,000 workers are exposed in general industry operations such as brick, concrete, and pottery manufacturing, as well as operations using sand products, such as foundry work and hydraulic fracturing (fracking) of oil and gas wells. Workers are also exposed during sandblasting in general industry, and maritime workplaces. 

The proposed rule is the result of extensive review of scientific evidence relating to the health risks of exposure to respirable crystalline silica, analysis of the diverse industries where worker exposure to crystalline silica occurs, and robust outreach efforts to affected stakeholders. OSHA has carefully considered current industry consensus standards on crystalline silica exposure, recommendations from small business representatives, and input from other interested parties and partner agencies in developing the proposed rule.

OSHA currently enforces 40-year-old permissible exposure limits (PELs) for crystalline silica in general industry, construction and shipyards that are outdated, inconsistent between industries, and do not adequately protect worker health. The proposed rule brings protections into the 21st century. The proposed OSHA PEL would limit workers’ exposures to a new PEL of 50 micrograms of respirable crystalline silica per cubic meter of air (μg/m3 ), averaged over an 8-hour day.

The Windsor Consulting Group, Inc. performed a longitudinal study of the OSHA inspector sampling database (1984 - 2013)  to determine the relative exposures for all industries. As previous reported in the unpublished literature, OSHA was aware that a significant percent of workers were exposed above the current standard, which is equivalent to about 100 Î¼g/m3 over an 8-hour  time-weighted average exposure. Our research indicates that workers across all industries are exposed to an average exposure close to the ACGIH TLV of 25 Î¼g/m3 over an 8-hour  time-weighted average with about 33.4% of the air samples exceeding this recommended guideline and only 10.5% of all air samples exceeding the NIOSH REL of 50 μg/m3 over an 8-hour  time-weighted average. A deeper analysis of all major industrial groups and specific industry groups, clearly indicates where the exposures occur. Crystalline silica dust was found in all industries including agriculture and forestry, mining, manufacture, construction, maritime, etc.

More importantly, our study indicated that the new OSHA standard should consider the ACGIH TLV as an action level and the NIOSH REL as the maximum permissible exposure limit. This evidence is supported by the statistical power within the largest sample sets - manufacture and construction industries. Like provisions in other OSHA health standards for lead, cadmium, hexavalent chromium, the two tiered exposure limits provide better protection for affected workers. With the use of engineering innovations and other water spray technology on equipment and machinery, using respirators and other personal protective clothing and equipment, providing medical surveillance of workers exposed to crystalline silica for more than 30-days a year, training and educating of workers on crystalline silica hazards and controls; and collaborating with industry and social media to reduce risk; occupational exposures in manufacture and construction are decreasing over time.

Similar success can be achieved for all other industries by developing sound policy, written programs, and standard operating procedures. Rates of silicosis are falling but more effort is needed to further reduce the risk of occupational disease from lung cancer, COPD, and other respiratory ailments and kidney disease. All stakeholders need to come together on this issue so that physicians, healthcare workers, insurance providers, regulatory policy makers, labor groups, universities and trade schools, business organizations, and industry associations can collectively make a difference to save the lives and health of affected workers. Silicosis and all related respiratory diseases is completely preventable with the right guidance and enforcement to protect industry/business most valued asset, its highly skilled and valued workers.

(Note: the information contained herein regarding the longitudinal study is pending publication. If you would like us to present our findings at a national conference or local chapter meeting, feel free to contact me at The Windsor Consulting Group, Inc.)