Characteristics of Dusts Encountered During the Production of Cemented Tungsten Carbides

Details

• Personal Author:
  Chipera SJ ; Chisholm WP ; Day, Gregory A. ; Harvey CJ ; Leonard, Stephen S. ; Sahakian NM ; Schwegler-Berry DE ; Stefaniak, Aleksandr B.
• Description:
  Inhalation of cobalt (Co) and tungsten carbide (WC) particles, but not Co or WC alone, may cause hard metal disease, risk of which does not appear to be uniform across cemented tungsten carbide (CTC) production processes. Inhalation of Co alone or in the presence of WC may cause asthma. Hypothesizing that aerosol size, chemical content, heterogeneity, and constituent compaction may be important exposure factors, we characterized aerosols from representative CTC manufacturing processes. Six work areas were sampled to characterize aerosol size distributions (dust, Co) and 12 work areas were sampled to characterize physicochemical properties (using scanning electron microscopy with energy dispersive x-ray spectrometry [SEMEDX]). Bulk feedstock and process-generated powders were characterized with SEM-EDX and x-ray diffraction. The dust mass median diameter was respirable and the cobalt respirable mass fraction was highest (37%) in grinding. Morphology of particles changed with processing: individual, agglomerate, or aggregates (pre-sintered materials), then mostly compacted particles (subsequent to sintering). Elemental composition of particles became increasingly heterogeneous: mostly discrete Co or W particles (prior to spray drying), then heterogeneous W/Co particles (subsequent work areas). Variability in aerosol respirability and chemical heterogeneity could translate into differences in toxicity and support detailed characterization of physicochemical properties during exposure assessments. [Description provided by NIOSH]
• Subjects:
  Aerosols Air Pollutants, Occupational Air Pollution, Indoor Chemistry Dust Environmental Monitoring Hazardous Substances Irritants Occupational Health Particulate Matter Respiratory Hypersensitivity Respiratory System Respiratory Tract Diseases Safety

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• Keywords:
  Aerosol-particles Air-contamination Air-quality-measurement Air-samples Airborne-dusts Airborne-particles Breathing Breathing-atmospheres Breathing-zone Chemical-properties Dust-analysis Dust-exposure Exposure-assessment Exposure-levels Particle-aerodynamics Particulate-dust Particulate-sampling-methods Particulates Respiratory-hypersensitivity Respiratory-irritants Respiratory-system-disorders Toxic-effects

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• ISSN:
  0019-8366
• 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 ; HELD - Health Effects Laboratory Division
• Topic:
  Workplace Safety & Health
• Location:
  North America
• Volume:
  45
• Issue:
  6
• NIOSHTIC Number:
  nn:20033194
• Citation:
  Ind Health 2007 Dec; 45(6):793-803
• Contact Point Address:
  Aleksandr B. Stefaniak, Division of Respiratory Disease Studies, National Institute for Occupational Safety and Health, Morgantown, West Virginia 26505
• CAS Registry Number:
  Cobalt (CAS RN 7440-48-4) ; Tungsten (CAS RN 7440-33-7)
• Federal Fiscal Year:
  2008
• Peer Reviewed:
  True
• Source Full Name:
  Industrial Health
• Collection(s):
  National Institute for Occupational Safety and Health
• Main Document Checksum:
  urn:sha-512:7da91c443ba06775da721e0b887004d97aef201cdc0e746f66923fb7b2c5fb7b97560d92beafe3f6842a0ee81823bf3707d06649e7d014d202cdf7de08cf625d
• Download URL:
  https://stacks.cdc.gov/view/cdc/188866/cdc_188866_DS1.pdf
• File Type:
  [PDF - 192.53 KB ]