Lung Response to Coal Dust and Crystalline Silica Exposure in Rats

Details

• Personal Author:
  Beck T ; Joseph P ; McKinney W ; Sager T
• Description:
  The role of crystalline silica in the re-emergence of coal workers pneumoconiosis reported in certain U.S. Appalachian states was investigated by employing an experimental rat model of lung toxicity. A computer-controlled, automated aerosol generation system was custom-built and employed to generate aerosols containing crystalline silica (Min-U-Sil 5) or coal dust (Keystone Mineral Black 325BA). Determination of the particle size distribution in the aerosol samples generated, using a micro-orifice uniform deposit impactor (MOUDI), showed a mass median aerodynamic diameter of 1.6 µm [geometric standard deviation (sg) 1.6] and 1.36 µm (sg 2.3), respectively, for the crystalline silica and coal dust particles. Male Fisher 344 rats (n=4/group) weighing approximately 200 g were used in the whole-body inhalation exposure lung toxicity study. The four exposure groups were: 1. Filtered-Air (6 hours/day, 5 days/week during week 1 followed by 6 hours/day, 4 days/week during weeks 2-5), 2. Min-U-Sil 5 (15 mg/m3, 6 hours/day, 5 days during week 1 followed by filtered air for 6 hours/day, 4 days/week during weeks 2-5), 3. Coal dust (filtered air for 6 hours/day, 5 days during week one followed by coal dust, 10 mg/m3, 6 hours/day, 4 days/week during weeks 2-5), and 4. Min-U-Sil 5 + coal dust (Min-U-Sil 15 mg/m3, 6 hours/day, 5 days during week 1 followed by coal dust, 10 mg/m3, 6 hours/day, 4 days/week during weeks 2-5). At the end of the fifth week, since the initiation of the first exposure, the rats were euthanized, and bronchoalveolar lavage (BAL) was performed to determine the induction of lung toxicity. Exposure of rats to Min-U-Sil 5 or coal dust alone did not change lactate dehydrogenase (LDH) activity in bronchoalveolar lavage (BAL) fluid at the post-exposure time interval when the analysis was performed. On the other hand, combined exposure of the rats to Min-U-Sil 5 and coal dust, at the same post-exposure time interval, resulted in a 1.3-fold increase in LDH activity suggesting a modest induction of lung toxicity in the rats, compared to the individual agents. Similarly, the number of PMNs detected in the Min-U-Sil 5 alone, coal dust alone, or Min-U-Sil 5 + coal dust exposed rats were 1.41-, 1.13-, and 4.24-fold higher than air controls, respectively, confirming mild, but enhanced lung toxicity of the combined exposure. A similar trend in the generation of oxidants by the lung phagocytes was detected in the rats exposed to the test agents alone or in combination. Collectively, these results indicate that the combined exposure to Min-U-Sil 5 (crystalline silica) and coal dust results in lung toxicity in the rats whereas exposure of either of the agents separately, under the conditions employed in the current study, did not result in significant lung toxicity. This data is consistent with the theory of potential involvement of crystalline silica in the re-emergence of coal workers pneumoconiosis reported in the US. [Description provided by NIOSH]
• Subjects:
  Aerosols Animals Coal Coal Mining Lung Lung Diseases Mining Occupational Health Respiratory System Respiratory Tract Diseases Safety Silicon Dioxide

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• Keywords:
  Aerosol Generators Animal Studies Black Lung Disease Coal Dust Coal Workers Pneumoconiosis Crystalline Silica Lung Tissue
• Series:
  Mining Publications
• ISSN:
  1096-6080
• Document Type:
  Text
• Genre:
  Abstract or Summary
• Place as Subject:
  OSHA Region 3 ; Pennsylvania ; West Virginia
• CIO:
  National Institute for Occupational Safety and Health (NIOSH)
• Division:
  HELD - Health Effects Laboratory Division ; PMRD - Pittsburgh Mining Research Division
• Topic:
  Workplace Safety & Health
• Location:
  North America
• Volume:
  192
• NIOSHTIC Number:
  nn:20067222
• Citation:
  Toxicologist 2023 Mar; 192(S1):344
• CAS Registry Number:
  Quartz (SiO2) (CAS RN 14808-60-7)
• Federal Fiscal Year:
  2023
• NORA Priority Area:
  Mining
• Peer Reviewed:
  False
• Source Full Name:
  The Toxicologist. Society of Toxicology 62nd Annual Meeting & ToxExpo, March 19-23, 2023, Nashville, Tennessee
• Collection(s):
  National Institute for Occupational Safety and Health
• Main Document Checksum:
  urn:sha-512:d3e3f011c8946483c99bc04ae70150ccdcf1919681e6e623b04378ec2b8777eb01a8d4cadae6556c6603b0742b61174c8b1b970bb29d50cc2ea027f86a67f8e8
• Download URL:
  https://stacks.cdc.gov/view/cdc/215615/cdc_215615_DS1.pdf
• File Type:
  [PDF - 1.11 MB ]