Fracking Sand Dust Elicits ROS and Pro-Inflammatory Cytokines from Murine Macrophage Cells

Details

• Personal Author:
  Fedan, Jeffery S. ; Leonard, Stephanie ; Morris A ; Olgun, Nicole S. ; Russ K
• 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 investigate whether pro-inflammatory signals are associated with inhaled FSD (<10 microm). We hypothesized that soluble and insoluble components in the FSD would each play a unique role in initiating pro-inflammatory responses and cytotoxicity. FSD was washed in PBS two separate times, 5 d each time, allowing for any soluble material to be released. On the 10th day of washing, sand that was twice washed was re-suspended in PBS (10 mg/ ml) so that comparisons could be made to a freshly prepared, unwashed mixture. Production of the hydroxyl radical (·OH), measured with electron paramagnetic resonance (EPR), was the highest in unwashed sand, followed by PBS from the 5 d and 10 d washes. Unwashed FSD sand also generated the most intracellular reactive oxygen species and the response was significantly larger than that obtained from FSD re-suspended after two consecutive washes. Cells were treated with a 1:2 and 1:10 dilution of stock solution. Compared to PBS controls, the viability of RAW 264.7 cells decreased by 40% following exposure to FSD that was washed and re-suspended after 10 days, whereas unwashed sand decreased viability by 30% over a 24 h period. Finally, production of the pro-inflammatory cytokines TNFalpha, IL-1beta, and IL-6 were measured using ELISA. While IL-1beta and IL-6 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 substantial differences in the production of cytokines stimulated by the soluble and insoluble components of FSD warrants future studies of the pro-inflammatory effects of the dust. [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 Cell Signaling Cellular Effects Cellular Reactions Chemicals Cytokines Cytotoxic Effects Cytotoxicity Dust Analysis Dust Inhalation ELISA Enzyme-linked Immunosorbent Assay Exposure Assessment Exposure Levels Fracking Free Radicals Hydraulic Fracturing Hydroxyl Groups Immune Reaction Immune System Insoluble Compounds Laboratory Animals Laboratory Testing Lung Cells Lung Fibrosis Natural Gas Reactive Oxygen Species ROS Sand Silica Silicon Dioxide Soluable Compounds Soluble

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• ISSN:
  1096-6080
• Document Type:
  Text
• Genre:
  Abstract or Summary
• Place as Subject:
  OSHA Region 3 ; OSHA Region 6 ; Texas ; 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:
  162
• Issue:
  1
• NIOSHTIC Number:
  nn:20051198
• Citation:
  Toxicologist 2018 Mar; 162(1):353
• CAS Registry Number:
  Silica (CAS RN 7631-86-9)
• Federal Fiscal Year:
  2018
• NORA Priority Area:
  Construction
• Peer Reviewed:
  False
• Source Full Name:
  The Toxicologist. Society of Toxicology 57th Annual Meeting and ToxExpo, March 11-15, 2018, San Antonio, Texas
• Collection(s):
  National Institute for Occupational Safety and Health
• Main Document Checksum:
  urn:sha-512:ab4de36d80b730a30607ad0e9dbba71ffa700744399e8d3701d30c0aec1475f638957c0e07510b2d716488cd60271fc260d123ebf78b2088e1348606c640d81f
• Download URL:
  https://stacks.cdc.gov/view/cdc/211281/cdc_211281_DS1.pdf
• File Type:
  [PDF - 838.91 KB ]