Characterization of Exposures Among Cemented Tungsten Carbide Workers. Part I: Size-Fractionated Exposures to Airborne Cobalt and Tungsten Particles

Details

• Personal Author:
  Day, Gregory A. ; Stefaniak, Aleksandr B. ; Virji, M. Abbas
• Description:
  As many as 30,000 workers in the United States of America are exposed to cemented tungsten carbides (CTC), alloys composed primarily of tungsten carbide and cobalt, which are used in cutting tools. Inhalation of cobalt-containing particles may be sufficient for the development of occupational asthma, whereas tungsten carbide particles in association with cobalt particles are associated with the development of hard metal disease (HMD) and lung cancer. Historical epidemiology and exposure studies of CTC workers often rely only on measures of total airborne cobalt mass concentration. In this study, we characterized cobalt- and tungsten-containing aerosols generated during the production of CTC with emphasis on (1) aerosol "total" mass (n=252 closed-face 37 mm cassette samples) and particle size-selective mass concentrations (n=108 eight-stage cascade impactor samples); (2) particle size distributions; and (3) comparison of exposures obtained using personal cassette and impactor samplers. Total cobalt and tungsten exposures were highest in work areas that handled powders (e.g., powder mixing) and lowest in areas that handled finished product (e.g., grinding). Inhalable, thoracic, and respirable cobalt and tungsten exposures were observed in all work areas, indicating potential for co-exposures to particles capable of getting deposited in the upper airways and alveolar region of the lung. Understanding the risk of CTC-induced adverse health effects may require two exposure regimes: one for asthma and the other for HMD and lung cancer. All sizes of cobalt-containing particles that deposit in the lung and airways have potential to cause asthma, thus a thoracic exposure metric is likely biologically appropriate. Cobalt-tungsten mixtures that deposit in the alveolar region of the lung may potentially cause HMD and lung cancer, thus a respirable exposure metric for both metals is likely biologically appropriate. By characterizing size-selective and co-exposures as well as multiple exposure pathways, this series of papers offer an approach for developing biologically meaningful exposure metrics for use in epidemiology. [Description provided by NIOSH]
• Subjects:
  Chromium Dust Environmental Monitoring Hypersensitivity Metals Metal Workers Nickel Occupational Health Safety Skin Skin Absorption

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• Keywords:
  Allergens Asthma Author Keywords: Aerosols Carbides Chromium-compounds Cobalt-alloys Cobalt-compounds Exposure-assessment Exposure Assessment Lung Cancer Lung Disease Metal-compounds Metal-dusts Metal-workers Nickel-compounds Size-selective Sampling Skin-absorption Skin-sensitivity Tools Tungsten-compounds

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• ISSN:
  1559-0631
• Document Type:
  Text
• Genre:
  Journal Article
• Place as Subject:
  OSHA Region 3 ; West Virginia
• CIO:
  National Institute for Occupational Safety and Health (NIOSH)
• Division:
  DRDS - Division of Respiratory Disease Studies
• Topic:
  Workplace Safety & Health
• Location:
  North America
• Pages in Document:
  475-491
• Volume:
  19
• Issue:
  5
• NIOSHTIC Number:
  nn:20035321
• Citation:
  J Expo Sci Environ Epidemiol 2009 Jul; 19(5):475-491
• Contact Point Address:
  Dr. Aleksandr B. Stefaniak, National Institute for Occupational Safety and Health, Division of Respiratory Disease Studies, Mailstop H-2702, 1095 Willowdale Road, Morgantown, WV 26505-2888
• Email:
  astefaniak@cdc.gov
• CAS Registry Number:
  Cadmium (CAS RN 7440-43-9) ; Chromium (CAS RN 7440-47-3) ; Cobalt (CAS RN 7440-48-4) ; Nickel (CAS RN 7440-02-0) ; Tantalum (CAS RN 7440-25-7) ; Titanium (CAS RN 7440-32-6) ; Tungsten (CAS RN 7440-33-7)
• Federal Fiscal Year:
  2009
• Peer Reviewed:
  True
• Source Full Name:
  Journal of Exposure Science and Environmental Epidemiology
• Collection(s):
  National Institute for Occupational Safety and Health
• Main Document Checksum:
  urn:sha-512:742df4923dd17b44f5740209510377c4d80eec36a95fb6eb7f513e003b70609fcd9e23523c05b5f12ac813acf023a6fe98b09c03f8bb11ce3d43400a447dae18
• Download URL:
  https://stacks.cdc.gov/view/cdc/187228/cdc_187228_DS1.pdf
• File Type:
  [PDF - 314.88 KB ]