News | Published May 21, 2014 | Written by Susan Ososkie, MS, CRNP, NP-C, occupational health, Mount Nittany Physician Group

Silicosis and the new OSHA silica standard

Susan Ososkie, MS, CRNP, NP-C, occupational health, Mount Nittany Physician Group

Silicosis is a lung disease that is caused by inhaling tiny bits of silica dust. Respirable crystalline silica is the portion of crystalline silica dust that is small enough to enter the gas exchange regions of the lung if inhaled. Silica dust causes fluid build-up and scar tissue in the lungs that impacts the ability to breath. Inhalation of silica is also associated with lung cancer, pulmonary tuberculosis, and other airway diseases, as well as to the development of autoimmune disorders and chronic kidney disease. 

Crystalline silica is a common mineral that is a part of sand, rock, and mineral ores like quartz. Crystalline silica occurs primarily as quartz and is a component of the sand and stone materials used to make everyday products such as concrete, brick and glass. At least 1.7 million U.S. workers are exposed to respirable crystalline silica in a variety of industries and occupations including construction, mining, sandblasting, brick making and hydrofracturing (fracking). Silicosis is not reversible, but it is preventable by mitigating exposure.

The Occupational Health and Safety Administration (OSHA) have developed a standard to protect the workforce from this hazard. The current standard for permissible exposure limits (PESLs) were adopted in 1971, shortly after the creation of OSHA, and have not been updated since. The standard is currently under revision to reflect the increased level of concern related to this very real occupational risk to workers. In fact, there are current recommendations that PELs be reduced by 50 percent. OSHA's proposal is based on requirements of the Occupational Safety and Health Act (OSH Act) and court interpretations of the Act. For health standards issued under Section 6(b) (5) of the OSH Act, OSHA is required to promulgate a standard that reduces significant risk to the extent that it is technologically and economically feasible to do so. The summary of the proposed rule, published in September 2013 states:

"The Occupational Safety and Health Administration (OSHA) proposes to amend its existing standard for occupational exposure to crystalline silica. The basis for issuance of this proposal is a preliminary determination by the Assistant Secretary of Labor for Occupational Safety and Health that employees exposed to respirable silica face a significant risk to their health at the current permissible exposure limits (PELs) and that promulgating these proposed standards will substantially reduce that risk." 

The new permissible exposure limit (PEL), calculated as an 8-hour, time-weighted average, is 50 micrograms of respirable crystalline silica per cubic meter of air (50 ug/m3). OSHA also proposes other ancillary provisions for employee protection such as preferred methods for controlling exposure, respiratory protection, medical surveillance, hazard communication and record keeping. OSHA is proposing two separate regulatory texts - one for general industry and maritime, and the other for construction - in order to tailor requirements to the circumstances found in these sectors.  

Generally, engineering controls to mitigate dust exposure offer the best protection. However, a combination of engineering controls, work practice, protective equipment, and product substitution where feasible, along with worker training is needed to protect workers. In hydofracturing, for example, engineering controls and work practice controls may be to mandate capping of unused fill ports on sand movers, thus reducing the amount of dust released; or, reducing the drop height between the sand transfer belt and blender hoppers. Limiting the number of workers and the time spent in high dust areas or performing some operations remotely physically limits the amount of exposure. Simply making sure that fresh water is applied to the site around the well mitigates the amount of free dust in the air. When engineering and work practice controls are not feasible or are not enough to reduce silical levels below OSHA PELs, employers must provide workers with respirators. When respirators are used, the employer must have a respiratory protection program that meets the requirements of OSHA's Respiratory Protection Standard (29CFR1910.134- which is currently under review). This program must include proper respirator selection, fit testing, medical evaluations and training. Workers must also be provided with information about the hazards of silica and other chemicals found in the workplace. And, as part of its National Emphasis on Silica Program, OSHA recommends that employers medically monitor all workers who may be exposed to silica dust levels at or above half the PEL. Recommended medical tests include:

  1. A medical exam that focuses on the respiratory system and includes a medical and work history                                                                                                                                                            
  2. A chest X-ray, evaluated by a qualified professional

OSHA recommends that these tests be repeated every three years if the employee has less than 15 years of silica exposure, every two years if the employee has 15-20 years of exposure, and every year if the employee has 20 or more years of exposure.

The new recommendations are currently in the draft phase, but is it expected that specific, enforceable mandates will be forthcoming. These new initiatives may have significant impact on employees, employers, and occupational health care providers. The occupational health team at Mount Nittany Physician Group is constantly monitoring changes in the industry that may impact workforce health. We are here as your resource to keep your workforce healthy, productive, and compliant with new industry mandates.

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