Fly ash-induced changes in hamster tracheal epithelium in vivo and in vitro

The effects of fly ash from a coal-fired power plant on tracheal epithelium of crRGH (SYR) Syrian golden hamsters were studied in organ cultures and after in vivo exposures. The tracheal epithelium of animals receiving 5-9 daily (5 d/wk) 3-h exposures to 2 mg fly ash per cubic meter showed large areas of basal cell hyperplasia and stratification. Surface alterations characteristic of stratified metaplasia were observed. Exposure to 1 mg/m3 produced diffuse basal cell hyperplasia. Hamster tracheal ring cultures exposed in vitro to 50 micrograms/ml fly ash for 1 h/d or to 10 micrograms/ml for 3h/d showed epithelial changes similar to those observed in vivo. Whole suckling hamster tracheas in organ culture exposed to fly ash at concentrations of 10 and 50 micrograms/ml for 1 or 3 h/d exhibited cornifying epidermoid metaplasia after 7 exposures. The most characteristic findings in surface cells were broad metaplastic areas with keratin formation.