In Vitro Toxicity Evaluation of Wood Dust Released from Sanding Wood with and Without a Wood Sealant Containing Zinc Oxide Nanoparticles

Details

• Personal Author:
  Burrelli L ; Erdely AD ; Eye T ; Griffith J ; Kodali VK ; Lippy B ; McKinney W ; Mike C ; Roberts, Jennifer R. ; West, Gavin H. ; Zeidler-Erdely PC ; Burrelli L ; Erdely AD ; Eye T ; Griffith J ; Kodali VK ; Lippy B ; McKinney W ; Mike C ; Roberts, Jennifer R. ; West, Gavin H. ; Zeidler-Erdely PC
• Description:
  Background and Purpose: Nanotechnology enabled products are currently being deployed in the construction industry to improve durability, strength, and life span. One such application that is finding widespread usage is the incorporation of zinc oxide (ZnO) into sealants to enhance the durability of wood and reduce use of harmful chemicals. The International Agency for Research on Cancer has classified wood dust as a Group 1 carcinogen and is known to cause cancer in the nasal cavity, paranasal sinuses, and nasopharynx. ZnO nanoparticles are known to cause pulmonary irritation, metal fume fever and systemic toxicity. We Investigated whether coating wood with a sealant containing ZnO alters the release characteristics of wood dust particulates during product handling and if ZnO nanoparticle coating amplified wood dust toxicity. Methods: Particles were collected from three sanding operations performed by a tradesperson using a random orbital sander on a plywood board, with and without a ZnO-sealant coating. To further determine the influence of size fraction on the toxicity profile, the collected dust was separated into PM5 and > PM5 particulate using a custom dust separation system equipped with a cyclone separator and an acoustical aerosol generator. The dose-response toxicity of the four-wood dust particulate (PM5 Wood Dust, PM5 Zinc Wood Dust, >PM5 Wood Dust and >PM5 Zinc Wood Dust) was evaluated using human bronchial epithelial cells (BEAS-2B) and differentiated human macrophages (THP-1) over a wide dose range of 0-156.25 µg/cm2 or 0-500 µg/ml. Results: Scanning mobility particle sizer measurements during the sanding operation showed highest differential particle number concentrations in the size range below 100 nm. Sanding treated wood did not release excess particle number compared to untreated wood. A Microorifice Uniform Deposit Impactor was used to monitor the aerodynamic size of the collected particles and found 96.8% of the particles to be ≤ 10µm and 75% of the particulate ≤ 5.6 µm. Electron microscopy revealed that the collected wood dust particles were in the micron size range and had an irregular morphology. The presence of zinc on the surface of wood dust was confirmed by energy-dispersive X-ray spectroscopy. Dynamic light scattering showed that both types of PM5 particulates had an average hydrodynamic aggregate diameter of 650 +/- 400 nm and no significant alteration with the coating. The uptake of both respirable wood dusts was confirmed in both cell types using transmission electron microscopy. The ferric reducing ability of the serum assay showed PM5 particulates to be more reactive than > PM5 particulates, but there was no change in reactivity between the zinc-coated and uncoated wood dust. Cytotoxicity in the epithelial cells did not alter with the zinc sealant coating compared to uncoated wood dust and the IC50 of PM5 Wood Dust, PM5 Zinc Wood Dust, >PM5 Wood Dust and >PM5 Zinc Wood Dust particulate is 7.1 (3-11), 7.5 (4 -11), 54.5 (12-97), 41.4 (21-62) µg/cm2, respectively. PM5 wood dust was 5-6-fold more toxic than > PM5 particulates. Membrane damage measured by lactate dehydrogenase (LDH) release showed a similar trend with PM5 particulates showing greater membrane damage compared to > PM5 particulates and no alteration due to coating. The differentiated macrophages were less sensitive than the epithelial cells but showed similar responses in cytotoxicity and membrane damage. Conclusions: Overall, the PM5 wood dust samples had greater toxicity than the larger particulate sample. Coating wood with a ZnO containing sealant did not change the toxicity of the wood dust in vitro in either of the size fractions. [Description provided by NIOSH]
• Subjects:
  Construction Industry Dust Occupational Health Particulate Matter Safety Wood
• Keywords:
  Construction Industry In Vitro Study Nanoparticles Particulates Sealants Wood Dusts Zinc Oxide
• ISSN:
  1096-6080
• Document Type:
  Text
• Genre:
  Abstract or Summary ; Abstract or Summary
• Place as Subject:
  Maryland ; OSHA Region 3 ; West Virginia
• CIO:
  National Institute for Occupational Safety and Health (NIOSH) ; National Institute for Occupational Safety and Health (NIOSH)
• Division:
  HELD - Health Effects Laboratory Division ; HELD - Health Effects Laboratory Division
• Topic:
  Workplace Safety & Health ; Workplace Safety & Health
• Location:
  North America ; North America
• Volume:
  198
• NIOSHTIC Number:
  nn:20069333
• Citation:
  Toxicologist 2024 Mar; 198(S1):309
• CAS Registry Number:
  Zinc oxide (ZnO) (CAS RN 1314-13-2) ; Zinc oxide (ZnO) (CAS RN 1314-13-2)
• Federal Fiscal Year:
  2024
• NORA Priority Area:
  Construction ; Construction
• Peer Reviewed:
  False
• Source Full Name:
  The Toxicologist. Society of Toxicology 63rd Annual Meeting & ToxExpo, March 10-14, 2024, Salt Lake City, Utah
• Collection(s):
  National Institute for Occupational Safety and Health
• Main Document Checksum:
  urn:sha-512:3972a3d2431315e672ba847d28b3120c6aed67a0a1638c42feb505c8746f37745234781698670793c2fc274765edf6e8dd9a8bd02667ef8159f6388619bce0fe
• Download URL:
  https://stacks.cdc.gov/view/cdc/207833/cdc_207833_DS1.pdf
• File Type:
  [PDF - 558.92 KB ]