Presence of Tungsten-Containing Fibers in Tungsten Refining and Manufacturing Processes

Details

• Personal Author:
  Fernback, Joseph E. ; McKernan JL ; Petersen, Martin R. ; Toraason MA
• Description:
  In tungsten refining and manufacturing processes, a series of tungsten oxides are typically formed as intermediates in the production of tungsten powder. The present study was conducted to characterize airborne tungsten-containing fiber dimensions, elemental composition and concentrations in the US tungsten refining and manufacturing industry. During the course of normal employee work activities, seven personal breathing zone and 62 area air samples were collected and analyzed using National Institute for Occupational Safety and Health (NIOSH) fiber sampling and counting methods to determine dimensions, composition and airborne concentrations of fibers. Mixed models were used to identify relationships between potential determinants and airborne fiber concentrations. Results from transmission electron microscopy analyses indicated that airborne fibers with length >0.5 µm, diameter >0.01 µm and aspect ratios > / = 3:1 were present on 35 of the 69 air samples collected. Overall, the airborne fibers detected had a geometric mean length approximately 3 µm and diameter approximately 0.3 µm. Ninety-seven percent of the airborne fibers identified were in the thoracic fraction (i.e. aerodynamic diameter < / = 10 µm). Energy dispersive X-ray spectrometry results indicated that airborne fibers prior to the carburization process consisted primarily of tungsten and oxygen, with other elements being detected in trace quantities. Based on NIOSH fiber counting 'B' rules (length > 5 µm, diameter < 3 µm and aspect ratio > / = 5:1), airborne fiber concentrations ranged from below the limit of detection to 0.085 fibers cm(-3), with calcining being associated with the highest airborne concentrations. The mixed model procedure indicated that process temperature had a marginally significant relationship to airborne fiber concentration. This finding was expected since heated processes such as calcining created the highest airborne fiber concentrations. The finding of airborne tungsten-containing fibers in this occupational setting needs to be confirmed in similar settings and demonstrates the need to obtain information on the durability and associated health effects of these fibers. [Description provided by NIOSH]
• Subjects:
  Air Pollutants, Occupational Dust Metals Minerals Occupational Health Particulate Matter Safety
• Keywords:
  Airborne-dusts Airborne-fibers Author Keywords: Airborne Mineral Fiber Electron Microscopy Fibrous-dusts Hard-metal Manufacturing Metal-dusts Metal-refining Metallic-dusts Metallic-minerals Metal Oxide Whisker Mineral-dusts Mineral-processing Tungsten-compounds Tungsten-minerals Tungsten-ore Tungsten Blue Oxide

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• ISSN:
  0003-4878
• Document Type:
  Text
• Genre:
  Journal Article
• Place as Subject:
  Ohio ; OSHA Region 5
• CIO:
  National Institute for Occupational Safety and Health (NIOSH)
• Division:
  DSHEFS - Division of Surveillance, Hazard Evaluations, and Field Studies ; DART - Division of Applied Research and Technology
• Topic:
  Workplace Safety & Health
• Location:
  North America
• Pages in Document:
  215-224
• Volume:
  53
• Issue:
  3
• NIOSHTIC Number:
  nn:20035188
• Citation:
  Ann Occup Hyg 2009 Apr; 53(3):215-224
• Contact Point Address:
  John L. Mckernan, Division of Surveillance, Hazard Evaluations and Field Studies, National Institute for Occupational Safety and Health, 4676 Columbia Parkway, Cincinnati, OH 45226
• Email:
  mckernan.john@epa.gov
• CAS Registry Number:
  Tungsten (CAS RN 7440-33-7)
• Federal Fiscal Year:
  2009
• Peer Reviewed:
  True
• Source Full Name:
  Annals of Occupational Hygiene
• Collection(s):
  National Institute for Occupational Safety and Health
• Main Document Checksum:
  urn:sha-512:32c2ee21cbed8827f62be83da4094a268f2619c4e7b0c3c687a322f216a43d8777583aa5e28a048b3d5acdec0f780365a343702d5d3572996fbcf6891dbfbd91
• Download URL:
  https://stacks.cdc.gov/view/cdc/187122/cdc_187122_DS1.pdf
• File Type:
  [PDF - 266.32 KB ]