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Lung inflammation after exposure to nonfibrous silicates increases with chelatable [Fe3+]
A J Ghio1, R J Pritchard, J R Lehmann
1National Health and Environmental Effects Research Laboratory, Environmental Protection Agency, Research Triangle Park, North Carolina 27711, USA.
Journal of Toxicology and Environmental Health
|September 1, 1996
Summary
Lung inflammation in rats increases with surface-bound iron on mineral oxides. This study links iron complexation on dust particles to increased oxidative stress and neutrophilic alveolitis, highlighting iron's role in respiratory inflammation.
Area of Science:
- Environmental Science
- Toxicology
- Materials Science
Background:
- Lung exposure to iron complexes is linked to neutrophilic alveolitis.
- Mineral oxides can complex iron on their surfaces, potentially influencing biological responses.
Purpose of the Study:
- To test the hypothesis that lung inflammation in rats increases with surface-complexed iron (Fe3+) on mineral oxides.
- To investigate the relationship between surface iron concentration, oxidant generation, and inflammatory responses in the lungs.
Main Methods:
- Intratracheal instillation of 10 mineral oxides with measurable surface Fe3+ into rats.
- Assessment of thiobarbituric acid (TBA)-reactive products (oxidant generation) and lavage neutrophils/protein (inflammation) at 4 days post-instillation.
- Correlation analysis between chelatable iron concentrations and inflammatory markers, excluding silicates with structural iron.
Main Results:
- All mineral oxides increased lavage neutrophils and protein compared to saline.
- A significant correlation was found between chelatable iron and TBA-reactive products (r = 0.82; p = .04) after excluding structural iron.
- Among dusts without structural iron, surface iron correlated with lavage protein (r = 0.80; p = .05) and showed a trend with neutrophils (r = 0.73; p = .10).
Conclusions:
- Mineral oxides complex iron cations on their surfaces.
- In vitro oxidant generation and in vivo acute lung inflammation increase with surface iron concentration in mineral oxides lacking structural iron.