Durability of ceramic fibers in the human lung. Preliminary results
Abstract
A proper understanding of the pulmonary toxicology of man-made mineral fibres (MMMF) requires information on their durability in the human lung but to date there is little information on this subject. Recently however, we have had the opportunity to document some interesting aspects of the short-term durability of ceramic fibres in human lung by analysing fibres recovered in broncho-alveolar lavage fluid obtained frorn seven men currently employed in the MMMF production industry. Fibres recovered from the lungs by lavage were characterized by analytical transmission electron microscopy. Both normal and highiy-transfonned ceramic fibres were detected. The transformed fibres exhibited a spectrum ofmorphological features and elemental compositions. Some retained a typical ceramic chemistry but were heavily coated with ironcontaining material. Others had a hollow tube morphology, made up offine iron-containing granules without any of the normal major ceramic elements. Such fibres were sometimes found lying under a bed ofsiliceous Seachate. It is hypothesized (hat the transformation process first involves a coating of the ceramic fibres with iron-containing granules, followed by a progressive dissolution of the structural elements. We conclude that some ceraraic fibres are not durable in the human lung.