Effect of welding fume exposure on silica-induced pulmonary toxicity in rats.

Details

• Personal Author:
  Joseph P ; McKinney W ; Mustafa M ; Sager TM ; Umbright CM
• Description:
  Mixed exposures to silica and welding fume are common in certain occupations. It is currently undetermined what health burden workers exposed to both silica and welding fume experience. The objective of this study was to determine the effect of welding fume on the lung response to silica exposure. Male Fischer 344 rats were exposed to air or silica (15 mg/m3, 6 hrs/day, 5 days). At 5- and 11-months post-silica exposure, rats received welding fume (20 mg/m3, 4 hrs/day, 4 days/week for 4 weeks) by inhalation. At 1 day post welding fume exposure bronchoalveolar lavage was conducted to assess pulmonary toxicity based on lactate dehydrogenase activity, oxidant production, cell counts, and cytokines. Lung gene expression changes were also assessed. The results showed that both silica and welding fume exposures resulted in lung toxicity, at both post-exposure time points. Both additive and synergistic lung responses were detected, based on the parameters analyzed. For example, silica or welding fume exposure, alone, resulted in neutrophil infiltration of 250 and 625 times, respectively, compared to the air-exposed controls at 12 months post-exposure. The combined exposure to silica and welding fume, however, caused neutrophil infiltration that was 1392 times higher compared to air controls. Silica or welding fume exposure alone resulted in significant increases in measured cytokine levels, compared to controls. However, the combined exposure of silica and welding fume caused a greater elevation of measured cytokine levels, at both post-exposure timepoints. For example, measured levels of MIP-2 were 37-fold and 35-fold higher in the silica alone and welding fume alone animals, respectively. However, the silica and welding fume combined exposure facilitated an additive effect, where the measured MIP-2 level was 45-fold higher. Furthermore, global gene expression changes in the lungs were detected in all exposure groups, at both 6- and 12-months post-exposure. For example, silica exposure alone resulted in 125 and 750 significantly differentially expressed genes (SDEGs), while the welding fume alone group had 1068 and 2255 SDEGs, and the silica-welding fume combined exposure had 1808 and 1910 SDEGs, at the 6- and 12-month time intervals, respectively. Together, these results suggest an additive/synergistic effect of the combined silica and welding fume exposure on the assessed lung toxicity parameters. [Description provided by NIOSH]
• Subjects:
  Animals Lung Occupational Health Respiratory System Safety Silicon Dioxide Toxicology Welding
• Keywords:
  Toxicology; Welding fumes; Welders; Silica; Animal studies; Lung tissue; Cytokines; Pulmonary effects; Mixed exposures
• ISSN:
  1096-6080
• Document Type:
  Text
• Genre:
  Abstract or Summary
• Place as Subject:
  OSHA Region 3 ; West Virginia
• 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:
  83-84
• Volume:
  186
• NIOSHTIC Number:
  nn:20064922
• Citation:
  Toxicologist 2022 Mar; 186(S1):83-84
• CAS Registry Number:
  Silica (CAS RN 7631-86-9)
• Federal Fiscal Year:
  2022
• NORA Priority Area:
  Manufacturing
• Peer Reviewed:
  False
• Source Full Name:
  The Toxicologist. Society of Toxicology 61st Annual Meeting & ToxExpo, March 27-31, 2022, San Diego, California
• Collection(s):
  National Institute for Occupational Safety and Health
• Main Document Checksum:
  urn:sha-512:c20dc35be173120726ab75fc2de127a2a8c8cb9c0a83fd1805b99d84ffebb451639a8f4d0b9994281dfdba91f4cd17431ebe82a76cdb458de2c58bd84d460b5f
• Download URL:
  https://stacks.cdc.gov/view/cdc/249275/cdc_249275_DS1.pdf
• File Type:
  [PDF - 259.56 KB ]