Chronic inhalation of short asbestos fibers.
Platek-SF; Groth-DH; Ulrich-CE; Stettler-LE; Finnell-MY; Stoll-M
Fundam Appl Toxicol 1985 Apr; 5(2):327-340
The effects of chronic exposure to short asbestos (1332214) fibers were studied in rats and monkeys. Male Sprague-Dawley-rats and cynomologous-monkeys were exposed to chrysotile-asbestos (12001295) fibers less than 5 micrometers (microm) in length and at a concentration of 1.0 milligram per cubic meter (mg/m3) 7 hours per day, 5 days a week for 18 months. Selected rats were killed 1, 3, 6, 12, 18, and 24 months after the start of exposure and examined for gross and histopathological abnormalities. The left lungs were removed and assayed for inflammatory responses using beta- glucuronidase, acid-phosphatase, and lactate-dehydrogenase (LDH). Open lung biopsies were performed on the monkeys 28 months after the start of exposure. No significant difference in the histochemical responses to beta-glucuronidase, acid-phosphatase, and LDH between exposed and control rats was seen. No gross or histopathological abnormalities that could be attributed to asbestos exposure were seen. Asbestos bodies adjacent to the terminal bronchioles in the lung biopsy samples of the exposed monkeys were observed. No fibrosis was observed. The authors note that the monkeys are being maintained and observed for signs of latent pulmonary disease. They conclude that inhalation exposures to 1mg/m3 chrysotile-asbestos containing fibers shorter than 5microm is insufficient to cause pulmonary fibrosis or tumors after 24 months. Other studies in which asbestos induced pulmonary fibrosis and lung tumors used asbestos containing high concentrations of fibers that were longer than 5microm. Fiber lengths are very important in inducing biological effects.
NIOSH-Author; Airborne-dusts; Respiratory-irritants; Pulmonary-function; Respiration; Pulmonary-congestion; Lung; Toxicology; Lung-function; Lung-cells; Toxic-materials; Toxic-effects
Fundamental and Applied Toxicology
International Research and Development Corporation, Matawan, Michigan 49071