Comparison of properties of dust in alveolar of rats and the workplace.

Objectives: The purpose of this study was to analyze the α-SiO₂ content, composition, dispersion, morphology, and free radical content of dust between the alveolar and the workplace, to explore the possible changes in the properties (especially the pathogenicity) of dust after it enters the lung.

Methods: We collected the dust in the workplace in HANDAN Coal mine. They were selected by a 400 mesh sieve and was made a suspension of 50 mg/ml, which would be used to perfuse into the trachea of rats. When one week, four weeks, eight weeks, fourteen weeks, twenty weeks after perfusing, we harvested dust in rats alveolar through lung lavage for further processing.

Results: In the animal test, typical fibrous nodules appeared 20 weeks after dust exposure. No inflammatory reaction was observed in the saline group. The results of animal experiments showed that there was no significant difference in the content of α-SiO₂ between dust in the workplace and the lung lavage (P > 0.05). The content of the Fe element gradually increased with dust exposure time. The 12 elements of Al, Mg, Si, Pb, Mn, Ni, Zn, Cu, Cr, Sb, Cd, and AS were reduced in the experiment group compared with the workplace group. The shape of the dust in the workplace was mostly spherical. The shape of the dust extracted from the lung lavage fluid was mostly blocky and angular, and a few dust edges were sharp, and more than 80% of the particle size was smaller than 5 μm, while less than 1% of the particle size was larger than 10 μm. The amount of hydroxyl radical released by lung lavage dust in phosphate buffer was higher than that of the workplace dust.

Conclusions: After the dust entered the alveoli, the content of α-SiO₂ in the dust did not change with dust exposure time, while the content of elements in the dust, the morphology, and dispersion of the dust changed. The ability of dust in alveoli to produce hydroxyl radicals in phosphate buffer was higher than that in the workplace.