Characterization of Engineered Stone Dust-Induced Reactive Oxygen Species Generation and Cytotoxicity in vitro

Details

• Personal Author:
  Mandler, W. Kyle ; Knepp, Alycia K. ; Leonard, Stephen S. ; McKinney, Walter G. ; Keeley, Sarah ; Qian, Yong
• Description:
  Engineered stone (ES) fabrication generates respirable dust containing crystalline silica (CS), linked to accelerated silicosis outbreaks. Mechanisms underlying this toxicity, particularly the role of particle aging, remain unclear. In the occupational setting, workers are exposed to engineered stone dust (ESD) upon generation by cutting and grinding ES; however, ESD-initiated toxicity is frequently studied in labs using aged particles. This study aimed to compare radical generation and in vitro cytotoxicity of fresh versus aged ESD. Three different respirable ES types (ES A: 60% CS; B: 20%; C: 0%), granite (30%), and Min-u-Sil 5 (MS5, 99.5%) were generated using an automated cutting system and analyzed either freshly stored under N2 at -80 degrees C or after aging in air at room temperature for 2 weeks. RAW 264.7 macrophages were exposed to particles (10 µg/well, 100 µg/ml, 31.25 µg/cm2, 24 hr), and viability, apoptosis, necrosis, and intracellular reactive oxygen species (ROS) were measured. Fresh ESD/granite exhibited significantly higher electron paramagnetic resonance (EPR) radical signals than aged counterparts and MS5. Fresh ES/granite reduced macrophage viability, while aged materials/MS5 did not. Apoptosis increased with all particles where fresh/aged difference occurred only in ES B. Necrosis rose markedly with fresh ES A. Intracellular ROS was elevated by some materials, but N-acetylcysteine (NAC) antioxidant failed to prevent cytotoxicity induced by fresh particles. In conclusion, freshly generated ESD displayed greater radical-generating capacity and distinct cytotoxic effects compared to aged ESD, influenced by factors beyond CS content. ROS-independent mechanisms appear crucial for acute cytotoxicity. These findings indicate particle aging as a critical factor in ESD toxicological assessment.
• Subjects:
  Dust Occupational Health Safety
• Keywords:
  Crystalline silica; Stone grinders; Cutting tools; Cytotoxicity; Reactive oxygen species; ROS; In vitro study; Cytotoxic effects; Dust particles
• ISSN:
  1528-7394
• Document Type:
  Text
• Genre:
  Journal Article
• Place as Subject:
  West Virginia ; Philadelphia Region [OSHA]
• 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:
  12 pdf pages
• Volume:
  89
• Issue:
  7
• NIOSHTIC Number:
  nn:20071077
• Citation:
  J Toxicol Environ Health A 2026 Apr; 89(7):304-314
• Email:
  wmandler@cdc.gov
• Federal Fiscal Year:
  2026
• Peer Reviewed:
  True
• Source Full Name:
  Journal of Toxicology and Environmental Health, Part A: Current Issues
• Collection(s):
  National Institute for Occupational Safety and Health
• Main Document Checksum:
  urn:sha-512:0d9a22611aa68710c117538c67ebeb68e7bcfb91420403f165caab88adb4e2c23fff189512a704b6cbfc61784a18efd4836d285dd86fb21696ad573f150217c8
• Download URL:
  https://stacks.cdc.gov/view/cdc/257853/cdc_257853_DS1.pdf
• File Type:
  [PDF - 7.50 MB ]