Inflammation but no DNA (deoxyribonucleic acid) damage in mice exposed to airborne dust from a biofuel plant

Objectives Particles in ambient air are associated with such health effects as lung diseases and cancer of the lung. Exposure to bioaerosols has been found to be associated with respiratory symptoms. The toxic properties of exposure to combustion and bioaerosol particles from biofuel plants have not been studied in detail. This study investigated whether exposure to dust from biofuel plants induces DNA (deoxyribonucleic acid) damage and inflammation in exposed mice. Methods DNA damage and inflammation were evaluated in mice exposed through the intratracheal installation of airborne dust collected at a biofuel plant at the straw storage hall and in the boiler room. The mice were given either a single dose of dust (18 or 54 mu g) or four doses of 54 mu g on each of four consecutive days. Control mice were exposed to a 0.9% sodium chloride solution. Results In the mice exposed to 4 x 54 mu g of dust, the lung tissue mRNA (messenger ribonucleic acid) levels of interleukin-6 (IL-6), monocyte chemoattractant protein-1 (MCP-1), and macrophage inflammatory protein-2 (MIP-2) were increased more than 10-fold if the dust was from the boiler room and 30- to 60-fold if the dust came from the straw storage hall. The levels of DNA strand breaks in broncheoalveolar lavage (BAL) cells from the mice exposed to dust did not differ from those in the control samples. Conclusions The results indicate that the instillation of dust from a biofuel plant, at doses corresponding to 2 weeks of exposure to human endotoxins, results in a strong inflammatory response without detectable DNA damage in BAL cells. The dust from the straw storage hall induced the strongest inflammatory response and had the highest concentration of most microbial components.