Biopersistence of fibrous thermal insulations (AES fibers) after heat exposure using intratracheal instillation technique

Abstract

Abstract Because refractory ceramic fibers (RCF) were classified as possibly pathogenic to humans, alkaline earth silicate (AES) wools have been used as a substitute product for high-temperature applications. All in vivo assays developed to evaluate its pathogenicity were assessed using as-received AES samples. The classification as a pathogen does not apply if the retention half-time for fibers longer than 20 μm is less than 40 days. Therefore, this work describes the evaluation of one AES sample after heat treatment, using the intratracheal instillation technique in rats. Over a three-month post-treatment period, the rats were dissected, and their lungs were examined. The half-time calculation for the retained fibers longer than 20 µm in the lungs was 56 days. Therefore, this AES sample after heat treatment could be presumed to have pathogenic potential for humans.