Hydraulic fracking sand dust produces a pro-inflammatory response in murine macrophage cells

Details

• Personal Author:
  Olgun, Nicole S.
• Description:
  Hydraulic fracturing is used in the majority of natural gas wells across the United States. Water, sand, and chemicals are delivered at high pressure to drilled wells to cause fractures in the shale formations, allowing for the release of natural gas. Fracking sand, comprised mainly of silica dioxide (SiO2), along with water and chemicals, is used to keep these fissures open. Silicosis is a pulmonary disease that affects workers exposed to inhaled silica and is characterized by inflammation and fibrosis, causing a decrease in lung capacity. Fracking sand dust (FSD) is generated during preparation of fracking fluid for injection. In this study, murine macrophage cells (RAW 264.7) were used to better understand the mechanisms of toxicity associated with inhaled FSD (< 10 microm). We hypothesized that the soluble and non-soluble components present in the FSD would each play a unique role in observed pro-inflammatory responses and cytotoxicity. FSD was washed in PBS twice, 5 days each time, allowing for any soluble material to be released (1st and 2nd washes, respectively). On the 10th day, sand that was twice washed was re-suspended in PBS (10mg/ml) so that comparisons could be made to a freshly prepared, unwashed mixture. Compared to similarly treated silica controls, the viability of cells (measured with a fluorogenic substrate) exposed to PBS from the 1st and 2nd washes were decreased by 40%, whereas unwashed sand decreased viability by 60% over a 24 h period. Intracellular ROS generation from sand washed once was significantly higher compared to sand that was washed twice. Unwashed FSD sand generated the most intracellular ROS and was significantly higher than sand re-suspended after two washes. Production of the hydroxyl radical (·OH) was also the highest in unwashed sand, followed by PBS from the first and second washes. Sand re-suspended in PBS after 10 days generated the least amount of ·OH. Finally, production of the pro-inflammatory cytokines IL-1beta and TNFalpha were measured using ELISA. While IL-1beta production decreased with washing, TNFalpha production remained elevated. Our results indicate that FSD is cytotoxic to RAW 264.7 cells, as evidenced by decreases in viability, and stimulates intracellular ROS and ·OH production. The stark differences in production between IL-1beta and TNFalpha stimulated by the dust warrants future studies into the pro-inflammatory effects of its soluble and insoluble components. [Description provided by NIOSH]
• Subjects:
  Blood Cells, Cultured Cytotoxins Dust Environmental Exposure Enzymes Free Radicals Immune System Laboratories Lung Lung Diseases Macrophages Occupational Health Respiratory System Respiratory Tract Diseases Safety Silicon Dioxide Toxicology

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• Keywords:
  Cell Cultures Cell Culture Techniques Cellular Effects Cellular Reactions Cytotoxic Effects Cytotoxicity Dust Analysis ELISA Enzyme-linked Immunosorbent Assay Exposure Assessment Exposure Levels Fracking Free Radicals Hydraulic Fracturing Hydroxyl Groups Immune Reaction Immune System Laboratory Animals Laboratory Testing Lung Cells Lung Fibrosis Natural Gas Reactive Oxygen Species ROS Sand Silica Silicon Dioxide

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• ISSN:
  1096-6080
• Document Type:
  Text
• Genre:
  Abstract or Summary
• Place as Subject:
  Maryland ; OSHA Region 3 ; West Virginia
• CIO:
  National Institute for Occupational Safety and Health (NIOSH)
• Division:
  HELD - Health Effects Laboratory Division
• Topic:
  Workplace Safety & Health
• Location:
  North America
• Volume:
  156
• Issue:
  1
• NIOSHTIC Number:
  nn:20049419
• Citation:
  Toxicologist 2017 Mar; 156(1):231
• CAS Registry Number:
  Silica (CAS RN 7631-86-9)
• Federal Fiscal Year:
  2017
• NORA Priority Area:
  Manufacturing
• Peer Reviewed:
  False
• Source Full Name:
  The Toxicologist. Society of Toxicology 56th Annual Meeting and ToxExpo, March 12-16, 2017, Baltimore, Maryland
• Collection(s):
  National Institute for Occupational Safety and Health
• Main Document Checksum:
  urn:sha-512:d229e044bf43f7899de8ab2ac4056bce04a6ba215368f6cbc91ce605e0c72cbbb2c50ff1be4440595b84c916cbdbe469c32dfcb7704f702fed4aca6c7a3e55fa
• Download URL:
  https://stacks.cdc.gov/view/cdc/203867/cdc_203867_DS1.pdf
• File Type:
  [PDF - 950.95 KB ]