Intratracheal instillation serves as a model for inhalation exposure. However, for this, materials are dispersed in appropriate media that may influence toxicity. We tested whether different intratracheal instillation dispersion media influence the pulmonary toxicity of different nanomaterials. Rodents were intratracheally instilled with 162 µg/mouse/1620 µg/rat
carbon black (CB), 67 µg/mouse
titanium dioxide nanoparticles (TiO2) or 54 µg/mouse
carbon nanotubes (CNT). The dispersion media were as follows: water (CB, TiO2); 2% serum in water (CB, CNT, TiO2); 0.05%
serum albumin in water (CB, CNT, TiO2); 10% bronchoalveolar lavage fluid in
0.9% NaCl (
CB), 10% bronchoalveolar lavage (BAL) fluid in water (CB) or 0.1% Tween-80 in water (CB).
Inflammation was measured as pulmonary influx of neutrophils into bronchoalveolar fluid, and DNA damage as
DNA strand breaks in BAL cells by comet assay.
Inflammation was observed for all nanomaterials (except 38-nm TiO2) in all dispersion media. For CB,
inflammation was dispersion medium dependent. Increased levels of
DNA strand breaks for CB were observed only in water, 2% serum and 10% BAL fluid in
0.9% NaCl. No dispersion medium-dependent effects on genotoxicity were observed for TiO2, whereas CNT in 2% serum induced higher
DNA strand break levels than in 0.05%
serum albumin. In conclusion, the dispersion medium was a determinant of CB-induced
inflammation and genotoxicity. Water seemed to be the best dispersion medium to mimic CB inhalation, exhibiting
DNA strand breaks with only limited
inflammation. The influence of dispersion media on nanomaterial toxicity should be considered in the planning of intratracheal investigations.