Progression of Lung Inflammation and Damage in Rats After Cessation of Silica Inhalation

Details

• Personal Author:
  Battelli L ; Brumbaugh K ; Castranova, Vincent ; Hubbs, Ann F. ; Khan A ; McLaurin J ; Mercer R ; Porter DW ; Ramsey D ; Robinson VA ; Teass A
• Description:
  Human epidemiologic studies have found that silicosis may develop or progress even after occupational exposure has ended, suggesting that there is a threshold lung burden above which silica-induced pulmonary disease progresses without further exposure. We previously described the time course of rat pulmonary responses to silica inhalation as biphasic, the initial phase characterized by increased but controlled pulmonary inflammation and damage. However, after a threshold lung burden was exceeded, rapid progression of silica-induced pulmonary disease occurred. To test the hypothesis that there is a threshold lung burden above which silica-induced pulmonary disease progresses without further exposure we initiated a study to investigate the relationship between silica exposure, the initiation and progression of silica-induced pulmonary disease, and recovery. Rats were exposed to silica (15 mg/m3, 6 h/day) for either 20, 40, or 60 days. A portion of the rats from each exposure were maintained without further exposure for 36 days to examine recovery. The major findings of this study are: (1) silica-exposed rats were not in pulmonary overload, and lung silica burden decreased with recovery; (2) pulmonary inflammation, damage and lipidosis increased with recovery for rats exposed to silica for 40 and 60 days, but not 20 days; (3) histopathology revealed changes in silica-induced alveolitis, epithelial hypertrophy and hyperplasia, and alveolar lipoproteinosis consistent with bronchoalveolar lavage (BAL) endpoints; and (4) pulmonary fibrosis developed even when exposure was stopped prior to its initial development. [Description provided by NIOSH]
• Subjects:
  Aluminum Silicates Irritants Lung Lung Diseases Occupational Health Respiratory System Respiratory Tract Diseases Safety Silicon Dioxide
• Keywords:
  Author Keywords: Silica Inhalation Lung-burden Lung-disease Lung-disorders Pulmonary-function Pulmonary-system Pulmonary-system-disorders Pulmonary Inflammation Recovery Respiratory-infections Respiratory-irritants Respiratory-system-disorders Silica-dusts Silica Lung Burden Silicates Silicosis

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• ISSN:
  1096-6080
• Document Type:
  Text
• Genre:
  Journal Article
• Place as Subject:
  Ohio ; OSHA Region 3 ; OSHA Region 5 ; West Virginia
• CIO:
  National Institute for Occupational Safety and Health (NIOSH)
• Division:
  HELD - Health Effects Laboratory Division ; DART - Division of Applied Research and Technology
• Topic:
  Workplace Safety & Health
• Location:
  North America
• Pages in Document:
  370-380
• Volume:
  79
• Issue:
  2
• NIOSHTIC Number:
  nn:20024935
• Citation:
  Toxicol Sci 2004 Mar; 79(2):370-380
• Contact Point Address:
  Dale W. Porter, Health Effects Laboratory Division, National Insitute for Occupational Safety and Health, 1095 Willowdale Road, M/S 2015, Morgantown WV, 26505
• Email:
  DPorter@cdc.gov
• CAS Registry Number:
  Quartz (SiO2) (CAS RN 14808-60-7)
• Federal Fiscal Year:
  2004
• Peer Reviewed:
  True
• Source Full Name:
  Toxicological Sciences
• Collection(s):
  National Institute for Occupational Safety and Health
• Main Document Checksum:
  urn:sha-512:5b90d0aca2ddf138db237049e7503e1293d5c5efa42aa11cde223c0bebf2979cdaa3b25148d08e89d2ca19e0be150ec30ba096e91201fbb37e4ed6d2280d777b
• Download URL:
  https://stacks.cdc.gov/view/cdc/196501/cdc_196501_DS1.pdf
• File Type:
  [PDF - 331.01 KB ]