Biological effects of inhaled hydraulic fracturing sand dust. IV. Pulmonary effects

• Published in: Toxicology and applied pharmacology 2020-12, Vol.409, p.115284-115284, Article 115284
• Main Authors: Russ, Kristen A., Thompson, Janet A., Reynolds, Jeffrey S., Mercer, Robert R., Porter, Dale W., McKinney, Walter, Dey, Richard D., Barger, Mark, Cumpston, Jared, Batchelor, Thomas P., Kashon, Michael L., Kodali, Vamsi, Jackson, Mark C., Sriram, Krishnan, Fedan, Jeffrey S.
• Format: Article
• Language: English
• Subjects: Administration, Inhalation; Animals; Dust; Epithelial Cells - drug effects; Fracking sand dust; Hydraulic Fracking - methods; Hydraulic fracturing; Inhalation Exposure - adverse effects; Lung; Lung - drug effects; Male; Methacholine Chloride - pharmacology; Occupational Exposure - adverse effects; Pulmonary toxicity; Rats; Rats, Sprague-Dawley; Respiratory Mucosa - drug effects; Sand - chemistry; Silicon Dioxide - adverse effects; Trachea - drug effects
• ISSN: 0041-008X; 1096-0333
• DOI: 10.1016/j.taap.2020.115284

Hydraulic fracturing creates fissures in subterranean rock to increase the flow and retrieval of natural gas. Sand (“proppant”) in fracking fluid injected into the well bore maintains fissure patency. Fracking sand dust (FSD) is generated during manipulation of sand to prepare the fracking fluid. Containing respirable crystalline silica, FSD could pose hazards similar to those found in work sites where silica inhalation induces lung disease such as silicosis. This study was performed to evaluate the possible toxic effects following inhalation of a FSD (FSD 8) in the lung and airways. Rats were exposed (6 h/d × 4 d) to 10 or 30 mg/m3 of a FSD collected at a gas well, and measurements were performed 1, 7, 27 and, in one series of experiments, 90 d post-exposure. The following ventilatory and non-ventilatory parameters were measured in vivo and/or in vitro: 1) lung mechanics (respiratory system resistance and elastance, tissue damping, tissue elastance, Newtonian resistance and hysteresivity); 2) airway reactivity to inhaled methacholine (MCh); airway epithelium integrity (isolated, perfused trachea); airway efferent motor nerve activity (electric field stimulation in vitro); airway smooth muscle contractility; ion transport in intact and cultured epithelium; airway effector and sensory nerves; tracheal particle deposition; and neurogenic inflammation/vascular permeability. FSD 8 was without large effect on most parameters, and was not pro-inflammatory, as judged histologically and in cultured epithelial cells, but increased reactivity to inhaled MCh at some post-exposure time points and affected Na+ transport in airway epithelial cells. •Fracking sand dust effects on ventilatory/non-ventilatory rat lung function studied.•Inhalation exposure 10 or 30 mg/m3 × 6 h/d × 4 d; 1, 7 and 27 d post-exposure.•Pulmonary function was unaffected; reactivity to inhaled methacholine was increased.•Tracheal epithelial Na+ transport was inhibited.•Otherwise, the dust lacked appreciable in vivo/in vitro bioactivity in rat airways.