Pulmonary toxicity associated with fly ash from fluidized bed coal combustion. II. Cellular morphometry of distal lung following a single intratracheal instillation.

Fly ash from an experimental fluidized bed coal combustor (FBC) was intratracheally instilled (once) into male Syrian golden hamsters at concentrations of 0 (control), 3, 10, 30, and 100 mg/animal. Thirty days postadministration, lungs were fixed by intratracheal perfusion, and tissues were processed for electron microscopic evaluation. Standard point count morphometry was used to analyze distal lung structures. Significant differences were found in volume density of noncellular interstitial space, with this compartment being increased in a dose-dependent manner. Volume density, numerical density, and average cellular volume of distal lung cells revealed no significant differences between treated and control animals. In addition, diffusion capacity and air-blood barrier thickness were not significantly altered in treated animals. The absence of cellular change at 30 days postexposure suggests a residual effect on noncellular interstitium, which may implicate fibrosis.