In vivo Lung Toxicity Associated with Boron Nitride Nanotubes with Different Purities

Details

• Personal Author:
  Roberts, Jennifer R. ; Xin, Xin ; Roach, Katherine A. ; Jakubinek, M. B. ; Kim, K. S. ; Bowers, Lauren N. ; Wolfarth, Michael G. ; Leonard, Stephen S. ; Porter, Dale W. ; Friend, Sherri A. ; Erdely, Aaron ; Kodali, Vamsi K.
  More +
• Description:
  Boron nitride nanotubes (BNNTs) are a high aspect ratio nanomaterial composed of hexagonal B-N in a multi-walled tube formation. Their material properties make them advantageous in applications in composites, energy storage, radiation and thermal shielding, as well as biomedical applications. The goal of this study was to assess the lung toxicity BNNTs with various purities in vivo. The National Research Council, Canada, provided three BNNT samples: a low purity as-produced sample with approx. 50% tubes (AP-BNNT), a purified sample with elemental boron removed (BRBNNT), and a highly purified washed/filtered BR-BNNT sample (W2-BNNT). Hexagonal boron nitride (h-BN, <100 nm in diameter) was used as a control material for synthesis by-products. Samples were characterized for material properties including purity and size in powder form and in dispersion medium (DM, vehicle control). Purity (tube concentration) varied with W2> BR >AP with tube dimensions of geometric mean length of 1.68 µm +/- geometric standard deviation (GSD) of 1.9 and a geometric mean diameter +/- GSD of 0.017 µm +/- 1.329 in powder form. Agglomerate sizes in DM ranged from approx. 285-350 nm for BNNT and h-BN. Male C57BL/6 mice were exposed by oropharyngeal aspiration to 4 or 40 µg of sample/mouse in DM or DM alone. Mice were euthanized at 4 h, 1 d, 7 d, 1 mo, and 3 mo post-exposure, lung lavage was performed to evaluate lung injury and inflammation on one group of animals. Lungs from a second group were collected for histopathology. Lavage parameters of lung injury and inflammation were significantly increased by the high dose of BNNTs at the early time points with W2>BR>AP and persisted in the W2 group up to 1 m post-exposure. h-BN produced low to no indicators of toxicity in lavage parameters measured. In lung tissue, inflammation and microgranuloma formation were noted with h-BN and BNNT exposures; however, severity was minimal to mild for all groups. Incidence and severity were greatest in the W2 group and began to resolve in all groups by 3 mo post-exposure. Recovery was fastest in the h-BN group. The results indicated that the tested BNNT samples induced acute toxicity and inflammation only at high concentration and the effects were more pronounced with increasing purity. The reference material used to represent one of the by-products of synthesis, h-BN, showed little toxicity relative to BNNT, suggesting effects where present may be due to BNNTs. Description provided by NIOSH
• Subjects:
  • Nanotubes, Carbon
  • Occupational Health
  • Particulate Matter
  • Respiratory System
  • Safety
• Keywords:
  • Boron nitride
  • Nanotubes
  • Nanomaterials
  • Particle size
  • In vivo study
  • Lung tissue
  • Toxic effects
• Document Type:
  Text
• Genre:
  Abstract
• Place as Subject:
  OSHA Region 3 ; West Virginia
• CIO:
  National Institute for Occupational Safety and Health (NIOSH)
• Division:
  HELD - Health Effects Laboratory Division
• Topic:
  Workplace Safety & Health
• Location:
  North America
• Pages in Document:
  2 pdf pages
• NIOSHTIC Number:
  nn:20071759
• Citation:
  13th International Particle Toxicology Conference, August 28-31, 2022, Santa Fe, New Mexico. Albuquerque, NM: University of New Mexico, 2022 Aug; :44
• CAS Registry Number:
  • Boron nitride (CAS RN 10043-11-5)
• Federal Fiscal Year:
  2022
• Peer Reviewed:
  False
• Download URL:
  https://stacks.cdc.gov/view/cdc/259984/cdc_259984_DS1.pdf
• File Type:
  [PDF - 665.76 KB]
• Collection(s):
  National Institute for Occupational Safety and Health
• Main Document Checksum:
  urn:sha-512:14f1455e63218734894c960f46b7e183dc4c10999ba4723c94be32014318a7f5e977ef809db8df2df2186ed47599358995ca66562b71b83a3442b09b0e43cb7f