Pulmonary fibrosis produced in F-344 XXXX by subchronic inhalation of aerosols of a 4000 molecular weight @entity11540 / @entity21806 polymer.

@entity11540 @entity21806 @entity82 @entity401 @entity548 @entity39 @entity133 @entity358 @entity1017 @entity35
Inhalation of aerosols of the @entity11540 / @entity21806 polymer (U-5100) evaluated in this study has previously been shown in acute and 2-week studies to produce toxicologic effects on the lungs, with increased lung weights and microscopic findings of congestion and @entity548 of @entity358 and @entity39 of alveolar epithelial cells (D. R. Klonne, D.J. Nachreiner, D. E. Dodd, P. E. Losco, and T.R. Tyler, 1987, Fundam. Appl. Toxicol. 9, 773-784). In the present studies, F-344 @entity35 were exposed 6 hr/day, 5 day/week for 2 weeks to aerosols at mean concentrations of 0, 0.9, or 5.0 mg/m3 or for 13 weeks to mean concentrations of 0, 0.3, 1.1, or 5.2 mg/m3. Following the 2-week study, minimal multifocal @entity548 and eosinophilic proteinaceous debris in alveoli were observed in the 0.9 mg/m3 group; similar lesions plus @entity39 were found in the 5 mg/m3 group. In the 13-week study, the 5.2 mg/m3 group had a slight decrease in body @entity1017 , while increases in absolute and/or relative lung weights occurred for both the 1.1 and 5.2 mg/m3 groups at the end of the exposure regimen and at the end of a 5-week recovery period. Histologic lesions of the lungs occurred in all U-5100-exposed groups and consisted of @entity548 , @entity133 , @entity401 , and multifocal @entity82 . The incidence and severity of the @entity358 were concentration related.(ABSTRACT TRUNCATED AT 250 WORDS)
