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A groundbreaking recent study authored by the National Institute for Occupational Safety and Health (NIOSH), “Occupational Exposures to Respirable Crystalline Silica During Hydraulic Fracturing,” discusses the harm related to an employee’s exposure to respirable crystalline silica during hydraulic fracturing (“fracking”). The study also includes recommendations for companies which utilize fracking in their operations.
Fracking involves the high pressure injection of large volumes of water or sand, and smaller amounts of well treatment chemicals, into a gas or oil well to fracture shale or other rock formations and release the hydrocarbons trapped inside. Crystalline silica (also known as “frac sand”) is often used as a proppant to hold open cracks and fissures created by the hydraulic pressure. The mechanical handling of frac sand creates respirable crystalline silica dust, which is a potential exposure hazard for workers. Specifically, frac sand is moved along transfer belts and by trucks for its use in the fracking process. This process often involves hundreds of thousands of pounds of frac sand, which creates airborne silica dust. Occupational exposure to respirable crystalline silica is already an established hazard in many industries, including those which involve mining, sandblasting, foundry work, agriculture, and construction, but not yet for oil and gas extraction work.
According to the authors, this new NIOSH study is the “first [known] systematic study of work crew exposures to crystalline silica during hydraulic fracturing.” The study cites occupational health knowledge gaps relating to fracking, including:
1) understanding which job titles have risks of chemical exposures;
2) quantifying the magnitude of exposure risks for both chemicals and minerals; and
3) understanding the relative contribution of all likely routes of exposure, including inhalation, dermal exposures, and ingestion.
Further, in noting the seriousness of the health impacts of crystalline silica, the study observes that the inhalation of respirable crystalline silica can cause health issues such as silicosis, lung cancer, autoimmune disorders, kidney disease, and an increased risk of tuberculosis.
NIOSH initiated the study to assess chemical exposures to oil and gas extraction workers in 2010. Approximately 435,000 workers were employed in the U.S. oil and gas extraction industry in 2010, nearly half of which were employed by well servicing companies, including companies that conducted fracking. To date, exposure assessments for respirable crystalline silica during fracking efforts have been the predominant focus of the NIOSH field effort.
In conducting the study, researchers at NIOSH collected personal breathing zone samples at well sites in five states (Colorado, Texas, North Dakota, Arkansas, and Pennsylvania) from workers with different job titles between August 2010 and September 2011, to evaluate worker exposure. At all sites, there were respirable silica samples which exceeded the occupational health criteria (e.g., The Occupational Safety and Health Administration’s (OSHA’s) personal exposure limit, the NIOSH recommended exposure limit, and/or the American Conference of Governmental Industrial Hygienists threshold limit value). In some instances, these crystalline silica exposures exceeded ten or more times the applicable occupational health criteria. Based on these evaluations, an occupational health hazard was determined to exist. In addition, seven points of dust generation were identified, including sand handling machinery and the dust generated from a work site itself.
According to the study, companies are just starting to implement controls to limit silica-containing dust generation during fracking due to the relatively recent understanding of the magnitude and hazards of exposure risks. Recommendations for companies that conduct hydraulic fracturing using frac sand include product substitution when feasible, engineering controls or modifications to sand handling machinery, administrative controls, and the increased use of proper personal protective equipment.
The study, published in the Journal of Occupational and Environmental Hygiene, is available here.