Objectives The aim of the study was to analyze the correlation between pulmonary concentrations of asbestos bodies and asbestos fibers and to characterize asbestos body counts from lung tissue of Finnish patients occupationally exposed and unexposed to asbestos.

Methods Ninety-nine surgically treated lung cancer patients were investigated. The number of asbestos bodies in iron-stained 5-µm histological lung tissue sections was determined by optical microscopy, and the pulmonary concentration of asbestos fibers was assessed by scanning electron microscopy. The correlation between asbestos body and asbestos fiber counts was calculated with linear regression. The asbestos body and asbestos fiber concentrations were also compared with exposure history according to a personal interview of the patients.

Results The average number of asbestos bodies ranged from <0.1 to 750 asbestos bodies per tissue section. All the cases with definite exposure showed an average of at least one asbestos body per tissue section. An average of at least one asbestos body per section was, however, detected in 34% of the patients with unlikely exposure. The regression equation log (AF)=-0.429+0.600.log (AB) was found to predict the concentration of asbestos fibers (AF, 106 fibers·g-1) corresponding to a given number of asbestos bodies (AB) in a section of lung tissue.

Conclusion The background level of asbestos bodies in the lungs of patients with no specific asbestos exposure seems to be higher in Finland than in other countries. In medicolegal cases, the methodological variation involved in asbestos fiber and asbestos body counting must be recognized and all available exposure data should be used to produce the best possible estimate of the exposure.

Key terms anthophyllite; crocidolite; electron microscopy; optical microscopy