Effect of thermal treatment on the surface characteristics and hemolytic activity of respirable size silica particles.

Details

• Personal Author:
  Bolsaitis P ; Keane MJ ; Razzaboni BL ; Wallace WE Jr.
• Description:
  The effect of thermal treatment on the surface properties and hemolytic activity of respirable silica particles was examined. Min- u-sil (14808607), Cab-o-sil (7631869), and cristobalite (14464461) were tested for their ability to hemolyze sheep blood erythrocyte suspensions before or after calcining by heating to 100 to 1095 degrees-C for 48 or 72 hours. Changes induced in surface structure were examined by photo acoustic infrared spectroscopic analysis and zeta potential measurements. The hemolytic activity of untreated Cab-o-sil was approximately 1 order of magnitude greater than that of untreated Min-u-sil when expressed on a per unit mass basis. Both dusts were significantly more hemolytic than cristobalite. When expressed on a per unit surface area basis the hemolytic potential of untreated Min-u-sil was approximately 3 to 4 times that of Cab-o-sil. The hemolytic potentials of untreated Cab-o-sil and cristobalite were comparable on this basis. Calcination decreased the hemolytic activity of Min-u-sil and Cab-o-sil. The lo of hemolytic activity was paralleled by a loss of infrared absorption bands characteristic of surface silanol groups. The calcined Min-u- sil and Cab-o-sil dusts gradually recovered their hemolytic potential when stored in desiccators. Recovery occurred within 10 to 30 days in the case of Cab-o-sil, but required at least 180 days in the case of Min-u-sil. The recovery of hemolytic activity was accompanied by an increase in infrared spectral bands characteristic of the hydroxylated surface. Calcination was accompanied by the zeta potentials becoming more negative. Min-u-sil samples that had lost 50% of their hemolytic activity after being heated to 800 degrees for 48 hours were treated with 5% sodium-hydroxide or 10% hydrochloric-acid. Min-u-sil recovered its full hemolytic potential after treatment with sodium-hydroxide, but not hydrochloric-acid. The authors conclude that the hemolytic activity of respirable silica particles can be correlated with the concentration of silanol groups on the surface.
• Subjects:
  Accidents, Occupational Education Hazardous Substances Manufacturing And Industrial Facilities Occupational Health Safety
• Keywords:
  Chemical Structure Cytotoxicity Hemolysis In Vitro Studies NIOSH Author Respirable Dust Silica Dusts Surface Properties Thermal Effects
• Publisher:
  National Institute for Occupational Safety and Health
• Document Type:
  Text
• Genre:
  Conference/Symposia Proceedings
• Place as Subject:
  OSHA Region 3 ; Pennsylvania
• CIO:
  National Institute for Occupational Safety and Health (NIOSH)
• Topic:
  Workplace Safety & Health
• Location:
  North America
• Pages in Document:
  215-230
• NIOSHTIC Number:
  nn:00198434
• Citation:
  Proceedings of the VIIth International Pneumoconioses Conference, August 23-26, 1988, Pittsburgh, Pennsylvania, USA. Atlanta, GA: U.S. Department of Health and Human Services, Public Health Service, Centers for Disease Control, National Institute for Occupational Safety and Health, DHHS (NIOSH) Publication No. 90-108, 1990 Sep; (Part I):215-230
• CAS Registry Number:
  Quartz (SiO2) (CAS RN 14808-60-7) ; Silica (CAS RN 7631-86-9) ; Cristobalite (CAS RN 14464-46-1)
• Federal Fiscal Year:
  1990
• Peer Reviewed:
  False
• Part Number:
  I
• Source Full Name:
  Proceedings of the VIIth International Pneumoconioses Conference, August 23-26, 1988, Pittsburgh, Pennsylvania, USA
• Collection(s):
  National Institute for Occupational Safety and Health
• Main Document Checksum:
  urn:sha-512:51af3d2d024c5935dcad62dc60525551ffa871b19b2a38647d1bae3cce2bcf003609e6fc4aedae934975827e2c8123d7b68930cc599cd3b1ad16af26111b7175
• Download URL:
  https://stacks.cdc.gov/view/cdc/180497/cdc_180497_DS1.pdf
• File Type:
  [PDF - 173.39 KB ]