Characterization of Dust Generated from Grinding Natural and Engineered Stones

Details

• Personal Author:
  Thompson, Drew ; Qi, Chaolong
• Description:
  Outbreaks of silicosis have been reported among stone countertop fabrication workers in the United States. Due to the high crystalline silica content in engineered stone, which can exceed 90%, dust controls currently employed in some fabrication worksites may not adequately limit exposure levels. In this study the dust generated by grinding natural and engineered stones was systematically characterized in a laboratory testing system. The stones tested included two engineered stones of crystalline silica in a polyester resin matrix (Stones A and B), an engineered stone of recycled glass in a cement matrix (Stone C), and granite. Particle size distributions were measured by Aerodynamic Particle Sizer. Aerosol samples were collected by respirable samplers, total dust samplers, and Micro-Orifice Uniform Deposit Impactor. Bulk dust samples were collected from the dust settled on the floor of the testing chamber. Samples were analyzed by gravimetric analysis and X-Ray diffraction to determine dust generation rates, crystalline silica generation rates, and crystalline silica content. No crystalline silica was detected in the bulk dust of Stone C. Stone A, Stone B, and granite bulk dust were 60%, 23%, and 30% crystalline silica, respectively. The crystalline silica content in bulk dust, respirable dust, and total dust were comparable for each stone type. Granite generated more dust per unit volume of material removed than the engineered stones, which all had similar dust normalized generation rates. Stone A had the highest crystalline silica normalized generation rates, followed by granite, Stone B, and Stone C (non-detect). For all stones containing crystalline silica, the highest size-dependent, normalized generation rate of respirable crystalline silica occurred at 3.2-5.6 µm. All stones generated similar trimodal lognormal particle size distributions, with the most prominent mode at 2-2.3 µm. These results will aid in the selection or development of optimal exposure control measures. Description provided by NIOSH
• Subjects:
  • Dust
  • Hazardous Substances
  • Occupational Health
  • Safety
  • Silicon Dioxide
• Keywords:
  • Crystalline silica; Countertops; Aerosols; Grinding equipment; Stone products; Respirable dust; Dust analysis; Silicosis
• Source:
  Abstracts from the AAAR 42nd Annual Conference, October 21-25, 2024, Albuquerque, New Mexico. Reston, VA: American Association for Aerosol Research, 2024 Oct; :262
• Document Type:
  Text
• Genre:
  Abstract or Summary
• Place as Subject:
  Chicago Region OSHA ; Ohio
• CIO:
  National Institute for Occupational Safety and Health (NIOSH)
• Division:
  DFSE - Division of Field Studies and Engineering
• Topic:
  Workplace Safety & Health
• Location:
  North America
• Pages in Document:
  1 pdf page
• NIOSHTIC Number:
  nn:20071692
• CAS Registry Number:
  • Quartz (SiO2) (CAS RN 14808-60-7)
• Federal Fiscal Year:
  2025
• Peer Reviewed:
  False
• Download URL:
  https://stacks.cdc.gov/view/cdc/259463/cdc_259463_DS1.pdf
• File Type:
  [PDF - 648.45 KB]
• Collection(s):
  National Institute for Occupational Safety and Health
• Main Document Checksum:
  urn:sha-512:a4d52c2075ad2766c2b887a2b6597f233dbe58ca0f4996d8c67addf1c27110f7808c3eb0d9b46eb6d95a459031ae1ecb3577ff38ad4d4ecfafc29603b86e4e28