Alveolar and lung fibre levels in non-occupationally exposed subjects.

Mineral fibre concentrations and characteristics were evaluated by the same electron microscope methods in 15 bronchoalveolar lavage samples and in 40 surgical lung tissue samples of subjects with no occupational exposure to asbestos. Both fibre alveolar load and lung burden evaluated by transmission electron microscopy were higher in the groups of industrial workers with no specific asbestos exposure than in the groups of individuals exposed only to general environmental pollution. In both types of samples, the fibre burden consisted of extremely small fibres (mean length less than 2 microns, mean diameter less than 0.1 micron), with a trend towards a further reduction in mean length in the lung tissue as compared with the alveolar load. These data suggest that there is a need for a critical reconsideration of the methods of evaluating environmental fibre pollution and of those for assessing exposure-effect relationships.