Respirable Crystalline Silica in the Workplace: New Occupational Safety and Health Administration (OSHA) Standards
Released: 2018-01-16T00:00:00

Overview of the New Standards

On March 25, 2016, the Occupational Safety and Health Administration (OSHA) of the Department of Labor (DOL) published in the Federal Register new standards governing exposure to respirable crystalline silica in the workplace. Key features of the new crystalline silica standards include the following requirements for employers:

protect workers when exposure to respirable crystalline silica exceeds the new permissible exposure limit (PEL) of 50 µg/m 3 (micrograms per cubic meter of air), as an 8-hour time-weighted average (TWA), through the use of engineering controls, or if such controls are not effective, the use of respirators; measure workers' exposure to respirable crystalline silica if such exposure may reach or exceed levels of 25 µg/m 3 as an 8-hour TWA; limit workers' access to areas where they may be exposed to respirable crystalline silica; offer medical exams, including chest x-rays and lung function tests, every 3 years to workers exposed to crystalline silica at or above the level of 25 µg/m 3 as an 8-hour TWA for 30 or more days in a year or to construction workers required to wear respirators for 30 or more days in a year; train workers to limit exposure to respirable crystalline silica; and maintain records of workers' exposure to respirable crystalline silica and employer-provided medical exams.

These new standards are to be phased in over a five-year period, beginning June 23, 2017, with different implementation dates for construction, general industry, and hydraulic fracturing (fracking).

The standards provide employers in the construction industry an exemption from the PEL and requirement to measure employee exposure to crystalline silica if these employers follow the engineering controls and work practices of the new standards, as outlined in Table 1 of the new standards. For example, if a stationary masonry saw is used in construction, the employer is exempt from the PEL and requirement to measure silica exposure if the following controls and practices are used:

Use saw equipped with integrated water delivery system that continuously feeds water to the blade. Operate and maintain tool in accordance with manufacturer's instructions to minimize dust emissions.

Crystalline Silica in the Workplace

Crystalline silica is a compound found in the earth's crust. It is a component of soil, sand, and other natural materials. The three most common forms of crystalline silica are quartz, cristobalite, and tridymite. Crystalline silica in dust commonly occurs when workers cut, saw, grind, drill, or crush materials such as glass, stone, rock, concrete, brick, or industrial sand. Exposure also occurs when industrial sand is used in abrasive operations, such as sandblasting, and in the hydraulic fracturing process.

The National Institute for Occupational Safety and Health (NIOSH) estimates that 1.7 million workers are exposed to crystalline silica in the workplace. However, NIOSH's estimates are based on 1986 data, which were published in 1991. In the preamble to its new crystalline silica standards, OSHA estimates that more than 2.3 million workers are potentially exposed to crystalline silica in the workplace, including more than 2 million workers in the construction industry.

Crystalline silica particles can be 100 times smaller than normal sand particles. Because of their small size, these particles can easily enter the human respiratory system. The International Agency for Research on Cancer (IARC) and the Department of Health and Human Services (HHS) National Toxicology Program has identified crystalline silica as a human carcinogen. The respiration of crystalline silica has been associated with the incurable disease silicosis and other respiratory diseases, such as pulmonary tuberculosis and lung cancer; auto-immune diseases, such as scleroderma, rheumatoid arthritis, and lupus; and renal disease and renal changes.

The health effects of crystalline silica and the link between occupational exposure to crystalline silica and silicosis and other diseases have been known since the beginning of the 20 th century, when cases of "consumption" and "phthisis" were documented among miners, stonecutters, glass workers, and other workers in the United States and other countries. In 1931, several hundred workers died of acute silicosis after being exposed to silica during the construction of Union Carbide and Carbon Corporation's Hawk's Nest Tunnel in Gauley Bridge, WV, making this exposure one of the deadliest single incidents of occupational disease in American history.

The federal government, under the provisions of the Energy Employees Occupational Illness Compensation Program Act (EEOICPA), currently provides a $150,000 cash benefit and health benefits to workers, or their survivors, who contracted chronic silicosis as a result of digging tunnels in Alaska and Nevada used for the underground testing of atomic weapons.

Rationale for the New Standards

In the preambles to its Notice of Proposed Rulemaking (NPRM) and Final Rule, OSHA lays out a detailed rationale for the new crystalline silica standards. OSHA claims that based on an extensive review of existing literature and research that identifies links between exposure to crystalline silica and various medical conditions, including silicosis, cancers, renal conditions, and other diseases, the new standards will prevent more than 600 silica-related deaths each year and reduce monetarized benefits by reducing mortality and morbidity, which far exceed projected costs of compliance.

In preparing its new crystalline silica standards, OSHA conducted a Preliminary Quantitative Risk Assessment and Final Quantitative Risk Assessment. Both assessments consisted of an extensive review of published literature and research on the health effects of occupational exposure to crystalline silica. OSHA performed these risk assessments in compliance with Section 6(b)(5) of the Occupational Safety and Health Act (OSH Act), which states, in part

Development of standards under this subsection shall be based upon research, demonstrations, experiments, and such other information as may be appropriate. In addition to the attainment of the highest degree of health and safety protection for the employee, other considerations shall be the latest available scientific data in the field, the feasibility of the standards, and experience gained under this and other health and safety laws....

Before the Preliminary Quantitative Risk Assessment, a draft health effects review document was subject to external peer review in accordance with Office of Management and Budget (OMB) guidelines. As a result of the Final Quantitative Risk Assessment, OSHA concludes in the preamble to its Final Rule:

[T]here is convincing evidence that inhalation exposure to respirable crystalline silica increases the risk of a variety of adverse health effects, including silicosis, NMRD [non-malignant respiratory disease] (such as chronic bronchitis and emphysema), lung cancer, kidney disease, immunological effects, and infectious tuberculosis (TB).

Permissible Exposure Limit

The new standards set a uniform PEL of 50 µg/m 3 measured as an 8-hour TWA. If workers are exposed to crystalline silica above the PEL, they must be protected through engineering controls, such as using water to control dust generated by a work process or respirators provided by the employer. Because the PEL is measured as an 8-hour TWA, a worker can be exposed to levels above the PEL periodically during the work day, provided that his or her average exposure over 8 hours does not exceed the 50 µg/m 3 .

Previous PELs

Prior to the promulgation of the new crystalline silica standards, the OSHA occupational safety and health standards (the old standards) did not include a universal PEL for all industries and types of crystalline silica. In addition, the PELs in the old standards, as published in the Code of Federal Regulations (C.F.R.), are not directly comparable to the new PELs. The PELs in the old standards are expressed as a formula of volume of crystalline silica per cubic meter of air, divided by the percentage of silicon dioxide (SiO 2 ); or as millions of particles per cubic foot of air, divided by the percentage of SiO 2 .

In its NPRM on the new standards, OSHA reports that the particle-count methodology used to determine the number of particles per cubic foot of air is obsolete.

In its NPRM, OSHA also provides the following estimates of the old-standard PELs expressed using the new methodology of µg/m 3 , measured as an 8-hour TWA:

quartz in general industry: 100 µg/m 3 ; quartz in construction industry: 250 µg/m 3 ; quartz in shipyard industry: 250 µg/m 3 ; cristobalite in all industries: 50 µg/m 3 ; and tridymite in all industries: 50 µg/m 3 .

The old-standard PELs trace their history to a report from the U.S. Public Health Service in 1929, which examined exposure to silica among workers in the granite-cutting industry in Barre, VT. The report recommended an exposure limit of between 10 million and 20 million particles per cubic foot (mppcf) for dust containing approximately 35% free silica (which includes crystalline silica) in the form of quartz and stated that this level could be "obtained by the use of economically practicable ventilating devices applied to the source of the dust." A review of the report stated

It should be pointed out that the limit established was not found to prevent the occurrence of silicosis. It was found, however, that there seemed to be no particular liability to pulmonary tuberculosis where the concentration of dust was within this limit.

OSHA's Original PELs

Section 6(a) of the OSH Act required OSHA to convert existing federal occupational safety and health standards and national consensus standards into OSHA standards within two years of enactment of the OSH Act. In 1971, OSHA's original PELs for crystalline silica were promulgated based on the existing PELs provided in regulations implementing the Walsh-Healey Public Contracts Act of 1936, which established certain standards for federal contractors. The Walsh-Healey regulations were based on the 1968 Threshold Limit Values (TLVs) established by the American Conference of Governmental Industrial Hygienists (ACGIH). The ACGIH TLVs were based on the recommendations in the 1929 U.S. Public Health Service Report.

OSHA's Attempt to Update the PELs

In 1989, OSHA updated nearly all of its PELs, including those for crystalline silica. The updated PELs for general industry were not increased, but rather were converted from the outdated formulas to measures of µg/m 3 of air. In 1992, OSHA proposed changing the crystalline silica PELs for the construction, agriculture, and maritime industries such that all industries would have the same PELs of 100 µg/m 3 for quartz and 50 µg/m 3 for cristobalite and tridymite. These changes would have resulted in a reduction in the PELs for the construction and maritime industries. In 1992, the U.S. Court of Appeals for the Eleventh Circuit vacated the 1989 changes to the PELs and mooted the 1992 proposed changes, thus returning the PELs back to their original levels set in 1971. These 1971 levels are replaced by the new PELs promulgated in 2016.

NIOSH Recommended PEL

In 1974, NIOSH issued a recommended PEL for crystalline silica of 50 µg/m 3 , measured as a 10-hour workday, 40-hour week TWA. In response to this recommendation, OSHA in 1974 published an Advanced Notice of Proposed Rulemaking (ANPRM) seeking public comments on whether a new crystalline silica standard should be promulgated based on the NIOSH recommendation or any other factors. More than 40 years after the NIOSH recommendation and the ANPRM, the new OSHA crystalline silica PEL now essentially matches the NIOSH recommendation, although it will be measured as an average over an 8-hour day.

Compliance Schedule

The new crystalline silica standards took effect June 23, 2016. However, employers were not required to comply with the new standards at that time. Rather, compliance is to be implemented according to the following schedule:

construction industry —September 23, 2017, except for provisions related to the analysis of air samples, which require compliance by June 23, 2018; good faith compliance assistance —On September 20, 2017, OSHA announced that during the first 30 days of enforcement of the standards for the construction industry, the agency would provide compliance assistance, rather than issue citations, to employers making "good faith efforts" to comply with the new standards. general industry (except hydraulic fracturing) and maritime industry —2 years after the effective date (June 23, 2018), except for medical surveillance, which is required to begin for employees exposed at or above the PEL for 30 days in a year by June 23, 2018, and for employees exposed at or above the level of 25 µg/m 3 by June 23, 2020; and hydraulic fracturing —2 years after the effective date (June 23, 2018), except for medical surveillance, which is required to begin for employees exposed at or above the PEL for 30 days in a year by June 23, 2018, and for employees exposed at or above the level of 25 µg/m 3 by June 23, 2020, and also except for engineering controls provisions, which require compliance by June 23, 2021.

Projected Costs and Benefits

OSHA projects that the implementation of its new crystalline standards will prevent 642 silica-related deaths per year and produce annual benefits of approximately $8.7 billion through mortality and morbidity reductions. OSHA also projects that annual benefits will be more than eight times greater than the annual projected costs of compliance with the new standards. The projected annualized costs of compliance with the standards are just over $1 billion, with 64% of these costs coming from implementing engineering controls. Table 1 provides OSHA's projected costs and benefits of the new crystalline silica standards.

Opposition to the New Standards

After OSHA published the NPRM on the new crystalline silica standards on September 12, 2013, several groups representing employers expressed their opposition to the proposed changes. These groups argued that OSHA had significantly underestimated the projected costs of the new standards and that the declining rate of silicosis deaths indicated that stricter standards and lower PELs were not necessary.

Cost Projections

In a March 2015 report, the Construction Industry Safety Coalition (CISC), made up of 25 trade associations representing employers that may be affected by the new standards, estimates that the proposed new standards will cost employers $4.9 billion annually. The CISC estimates annual direct compliance costs of $3.9 billion and indirect costs due to higher prices for building materials of more than $1 billion. The CISC's cost estimate is significantly higher than OSHA's cost estimate of just over $1 billion in the preamble to the Final Rule.

Benefit Projections

The Crystalline Silica Panel of the American Chemistry Council (ACC), composed of representatives from mining and mineral associations and industries, claims that evidence shows the current OSHA crystalline silica PELs are effective at reducing silica-related deaths and thus do not need to be changed. The ACC claims that data from the Centers for Disease Control and Prevention (CDC) indicate a nearly 90% reduction in annual silicosis deaths between 1968 and 2010. The ACC attributes this reduction, in part, to the current PELs adopted in 1971.

The CDC states that the reduction in silicosis deaths in this period is likely due to two factors. First, the higher numbers of deaths in the early period of the data may be capturing workers who were exposed to crystalline silica and contracted silicosis before the original OSHA PELs were implemented in 1971, mine safety regulations under the Coal Mine Safety and Health Act of 1969 and the Mine Safety and Health Act of 1977, and a greater use of engineering controls and other measures to control crystalline silica exposure. Second, there has been a reduction in the number of workers in heavy industries, such as the mining industry, where silica exposure is prevalent. In the preamble to its NPRM, OSHA calls these factors identified by the CDC "reasonable."

In addition, the ACC claims that better compliance with current PELs, not lower PELs, is the key to reducing silicosis deaths among workers. Annual silicosis mortality data are shown in Figure 1 .

In public comments in response to the NPRM, the ACC, the U.S. Chamber of Commerce, the National Utility Contractors Association, and the National Federation of Independent Business all argued that OSHA's projection of the new standards preventing 642 annual deaths from silicosis and non-malignant respiratory diseases (NMRD) in the NPRM exceeded the number of silicosis-related deaths reported in 2010 by the CDC and cited this as evidence that OSHA had overstated the benefits of the proposed standards.

In response to these objections, OSHA claims that commenters are making "apples and oranges" comparisons because the industry's objections focus on the number of deaths attributable to silicosis only, whereas OSHA's projections are for the number of deaths from silicosis and other NMRD prevented by the new standards.

Legislative Activity in the 114th Congress

In Section 115 of its FY2016 appropriations bill, S. 1695 , the Senate Committee on Appropriations included a provision that would have prohibited OSHA from spending any appropriated funds to implement any change to the crystalline silica standards until

a review is conducted, after the date of enactment, by a small business advocacy review (SBAR) panel (commonly referred to as a SBREFA panel) under the provisions of the Small Business Regulatory Enforcement Fairness Act (SBREFA) of 1996, and a report of this panel is submitted to OSHA; and OSHA commissions a study by the National Academy of Sciences (NAS), and reports on the results of this study to the Senate Committees on Appropriations and Health, Education, Labor, and Pensions within one year of enactment of the legislation, to examine the epidemiological justification for reducing the crystalline silica PEL, "including consideration of the prevalence or lack of disease and mortality associated" with the current PELs; the ability to collect and measure samples of crystalline silica at levels below the proposed PELs and below the level of 25 µg/m 3 ; the ability of regulated industries to comply with the proposed standards; the ability of various types of personal protective equipment (PPE) to protect workers from crystalline silica exposure; and the costs of various types of PPE compared with the costs of engineering controls and work practices.

S. 1695 would have appropriated $800,000 to OSHA to conduct the NAS study. S. 1695 was reported by the Senate Committee on Appropriations, but was not voted on by the Senate. The crystalline silica provisions were not included in the Consolidated Appropriations Act, 2016, P.L. 114-113 .

Legal Challenges

In the weeks after the Final Rule was published, legal challenges to the new crystalline silica standards were initiated by groups representing employers, manufacturers, and labor. The U.S. Judicial Panel on Multidistrict Litigation ruled that these petitions for review were to be consolidated in the U.S. Court of Appeals for the D.C. Circuit.

Employers and manufacturers challenged the standards on the basis of the following five issues:

1. whether substantial evidence supports OSHA's finding that limiting workers' silica exposure to the level set by the new standards reduces a significant risk of material health impairment; 2. whether substantial evidence supports OSHA's finding that the standards are technologically feasible for the foundry, hydraulic fracturing, and construction industries; 3. whether substantial evidence supports OSHA's finding that the standards are economically feasible for these industries; 4. whether OSHA violated the Administrative Procedure Act in promulgating the new standards; and 5. whether substantial evidence supports the provision that allows workers who undergo medical examinations to keep the results confidential from their employers, the provision that prohibits employers from using dry cleaning methods unless doing so is infeasible.

Labor groups challenged the following:

1. the requirement that medical surveillance for construction workers be provided only if the employee has to wear a respirator for 30 days for 1 employer within a 1-year period; and 2. the absence of medical removal provisions.

The U.S. Court of Appeals for the D.C. Circuit decided the case on December 22, 2017, and upheld the new standards. In its decision, the court rejected all challenges brought by manufacturers and employers as well as labor groups' objections to the medical surveillance provision. On the issue of medical removal raised by labor groups, the court held that OSHA had acted in an "arbitrary and capricious" manner in declining to require medical removal of a worker in cases in which a medical professional recommends permanent removal of the worker, when a medical professional recommends temporary removal of the worker to alleviate symptoms of chronic obstructive pulmonary disease (COPD), or when a medical professional recommends temporary removal of a worker pending a further determination by a medical specialist. The court remanded these issues to OSHA for reconsideration or further explanation.