Carbon nanotube and nanofiber exposure assessments: an analysis of 14 site visits

Details

• Personal Author:
  Birch, M. Eileen ; Dahm, Matthew M. ; Deddens JA ; Evans DE ; Fernback, Joseph E. ; Schubauer-Berigan, Mary K.
• Description:
  Recent evidence has suggested the potential for wide-ranging health effects that could result from exposure to carbon nanotubes (CNT) and carbon nanofibers (CNF). In response, the National Institute for Occupational Safety and Health (NIOSH) set a recommended exposure limit (REL) for CNT and CNF: 1 microg m(-3) as an 8-h time weighted average (TWA) of elemental carbon (EC) for the respirable size fraction. The purpose of this study was to conduct an industrywide exposure assessment among US CNT and CNF manufacturers and users. Fourteen total sites were visited to assess exposures to CNT (13 sites) and CNF (1 site). Personal breathing zone (PBZ) and area samples were collected for both the inhalable and respirable mass concentration of EC, using NIOSH Method 5040. Inhalable PBZ samples were collected at nine sites while at the remaining five sites both respirable and inhalable PBZ samples were collected side-by-side. Transmission electron microscopy (TEM) PBZ and area samples were also collected at the inhalable size fraction and analyzed to quantify and size CNT and CNF agglomerate and fibrous exposures. Respirable EC PBZ concentrations ranged from 0.02 to 2.94 microg m(-3) with a geometric mean (GM) of 0.34 microg m(-3) and an 8-h TWA of 0.16 microg m (-3). PBZ samples at the inhalable size fraction for EC ranged from 0.01 to 79.57 microg m(-3) with a GM of 1.21 microg m(-3). PBZ samples analyzed by TEM showed concentrations ranging from 0.0001 to 1.613 CNT or CNF-structures per cm(3) with a GM of 0.008 and an 8-h TWA concentration of 0.003. The most common CNT structure sizes were found to be larger agglomerates in the 2-5 microm range as well as agglomerates >5 microm. A statistically significant correlation was observed between the inhalable samples for the mass of EC and structure counts by TEM (Spearman p = 0.39, P < 0.0001). Overall, EC PBZ and area TWA samples were below the NIOSH REL (96% were <1 microg m(-3) at the respirable size fraction), while 30% of the inhalable PBZ EC samples were found to be >1 microg m(-3). Until more information is known about health effects associated with larger agglomerates, it seems prudent to assess worker exposure to airborne CNT and CNF materials by monitoring EC at both the respirable and inhalable size fractions. Concurrent TEM samples should be collected to confirm the presence of CNT and CNF. [Description provided by NIOSH]
• Subjects:
  Dust Environmental Monitoring Hazardous Substances Inhalation Exposure Manufacturing And Industrial Facilities Microbiology Occupational Health Particulate Matter Safety
• Keywords:
  Air-quality-monitoring Air-sampling Analytical-Method Author Keywords: Carbon Nanofibers Breathing-zone Carbon-compounds Carbon Nanotubes Exposure-assessment Exposure-levels Exposure-limits Exposure Assessment Fibrous-bodies Hazardous-materials Industrial-environment Inhalants Microscopic-analysis Nanomaterials Nanotechnology Respirable-dust Sampling Sampling-methods Time-weighted-average-exposure

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• ISSN:
  0003-4878
• Document Type:
  Text
• Funding:
  Interagency Agreement
• 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
• Volume:
  59
• Issue:
  6
• NIOSHTIC Number:
  nn:20046053
• Citation:
  Ann Occup Hyg 2015 Jul; 59(6):705-723
• Contact Point Address:
  Matthew M. Dahm, Industrywide Studies Branch, Division of Surveillance, Hazard Evaluations, and Field Studies, National Institute for Occupational Safety and Health, 1090 Tusculum Ave, MS-R14, Cincinnati, OH 45226, USA
• Email:
  mdahm@cdc.gov
• CAS Registry Number:
  Carbon (CAS RN 7440-44-0)
• Federal Fiscal Year:
  2015
• NORA Priority Area:
  Public Safety ; Manufacturing
• Peer Reviewed:
  True
• Source Full Name:
  Annals of Occupational Hygiene
• Collection(s):
  National Institute for Occupational Safety and Health
• Main Document Checksum:
  urn:sha-512:1bc49b3ac9863c082b96e2cf807a3db825f8248ce3090e861373acd24988c612e76ba5e5f309c6cac6721db2112c2fecdd6733f78cc1a2b1b47d908559c2ec1c
• Download URL:
  https://stacks.cdc.gov/view/cdc/201235/cdc_201235_DS1.pdf
• File Type:
  [PDF - 2.11 MB ]