Characterization and Toxicity Assessment of Aerosolized Particles Generated During Cutting of Carbon Nanotubes-Embedded Concrete

Details

• Personal Author:
  Afshari A ; Erdely A ; Eye T ; Fraser K ; Gill R ; Kodali V ; Lee E ; McKinney W ; Roberts, Jennifer R.
• Description:
  Carbon nanotube (CNT) as a reinforcement enhances durability and performance of concrete composites. Exposure to some forms of CNT is known to cause adverse pathological outcomes. To understand potential toxicity arising from use of CNT-enabled concrete composites as it goes through various occupational life cycle stages, we evaluated 1) the physicochemical characteristics and toxicity of the as-produced CNT and 2) how particulate release during concrete manipulation (e.g., cutting) is altered by CNT incorporation. Physical dimensional profiling indicated the as-produced CNT had a geometric mean length of 0.72 µm and 32 nm in diameter. Pulmonary injury and inflammation exerted by the CNT was assessed by exposing C57BL/J mice by oropharyngeal aspiration to a bolus dose of 4 and 40 µg. Animals were sacrificed on 1, 7 and 28 days to access toxicity. The toxicity of the as-produced CNT was similar to an agglomerated CNT studied in our previous research, lacking the more severe toxicity associated with longer length and diameter CNT. Mechanism-based screening of the initiating events in vitro in differentiated THP-1 macrophages were predictive of the in vivo outcome observed. For evaluating the second aim, three types of concrete blocks, 0% (reference), low%, and high% CNT, were tested in a custom designed enclosure housing an apparatus for the cutting of a block with an automated computer-controlled process. The highest particle number concentration (163,821 particles/cm3) was measured for the reference cylinder, while others showed similar concentrations (131,689 particles/cm3 and 140,954 particles/cm3 for the low% and high% blocks, respectively). There was no shift in the size distribution of the released aerosols from addition(s) of CNT. The released particulate was predominantly respirable particulate consisting of quartz, feldspar, etc. and often appeared to be agglomerated materials that included both paste and aggregate minerals with an aerodynamic diameter approx. 5µm. No free CNT were observed by electron microscopy from low% and high% samples. Toxicity screening of the released particulate is still ongoing but based on the size distribution profiles of the released aerosols, not a remarkable alteration in toxicity is expected from the particulate released due to addition of CNT to concrete. [Description provided by NIOSH]
• Subjects:
  Aerosols Animals Occupational Exposure Occupational Health Respiratory System Safety
• Keywords:
  Aerosol Particles Animal Studies Carbon Nanotubes CNT Concretes Inhalation Studies Nanomaterials Occupational Exposure
• ISSN:
  1096-6080
• Document Type:
  Text
• Genre:
  Abstract or Summary
• Place as Subject:
  OSHA Region 3 ; West Virginia
• CIO:
  National Institute for Occupational Safety and Health (NIOSH)
• Division:
  HELD - Health Effects Laboratory Division ; RHD - Respiratory Health Division
• Topic:
  Workplace Safety & Health
• Location:
  North America
• Volume:
  192
• NIOSHTIC Number:
  nn:20067233
• Citation:
  Toxicologist 2023 Mar; 192(S1):499
• CAS Registry Number:
  Carbon nanotubes (CAS RN 308068-56-6)
• Federal Fiscal Year:
  2023
• NORA Priority Area:
  Construction
• Peer Reviewed:
  False
• Source Full Name:
  The Toxicologist. Society of Toxicology 62nd Annual Meeting & ToxExpo, March 19-23, 2023, Nashville, Tennessee
• Collection(s):
  National Institute for Occupational Safety and Health
• Main Document Checksum:
  urn:sha-512:a59da8e77db4848e298c4b0b6f5e7f78d8f0fbf3a18bc98cebe665c78e5e6552e29fcbe6a34e15776704fa37999861a18f7a24d12fd39c8b94b52e598a01a7ea
• Download URL:
  https://stacks.cdc.gov/view/cdc/231356/cdc_231356_DS1.pdf
• File Type:
  [PDF - 1.09 MB ]