Lung Asbestos Fibre Burden and Pleural Mesothelioma in Women with Non-occupational Exposure

Background Malignant pleural mesothelioma (MPM) due to environmental and familial (domestic) asbestos exposure is well recognized. However, information on cumulative asbestos dose in subjects affected by MPM is limited. Objectives To evaluate the residual lung asbestos fibre and asbestos body burden in women with MPM with past environmental and/or familial asbestos exposure. Methods We collected lung samples from autopsies regarding 15 non-occupationally asbestos-exposed MPM cases, divided in three groups: (i) familial exposure from the Fincantieri shipyards in Monfalcone (No. 7), (ii) environmental and familial asbestos exposure from the asbestos-cement plant Fibronit in Broni (No. 6), and (iii) environmental exposure from the Fibronit plant (No. 2). Asbestos body (AB) and fibres (AF) per gram of dry lung tissue were counted by optical and scanning electron microscopy, respectively, and expressed as geometric means and standard deviations (GM, GSD). Results GM/GSD of AB counts were 6123/9.6 (Group 1), 13 800/10.4 (Group 2), and 8400/1.1 (Group 3); GM/GSD of AF were 0.6/2.1 (Group 1), 7.9/2.1 (Group 2), and 6.0/2.3 (Group 3) million. Pleural plaques were observed in 12 cases. Conclusions Exclusive familial exposure to asbestos determined cumulative doses close to those observed in moderate occupational exposure circumstances. Our results also suggest that combined environmental and familial exposures may cause unexpectedly high cumulative fibre doses.

The asbestos fibre burden in human lungs: new insights into the chrysotile debate

The traceability of asbestos fibres in human lungs is a matter of discussion especially for chrysotile. This issue is of high significance for differential diagnosis, risk assessment and occupational compensation. At present no intra-individual longitudinal information is available. This study addresses the question whether the asbestos fibre burden in human lungs decreases with time after exposure cessation.The database of the German Mesothelioma Register was screened for patients with asbestos body counts of at least 500 fibres per gram of wet lung, which had been analysed twice from different tissue excisions at minimum intervals of 4 years.Twelve datasets with individual longitudinal information were discovered with a median interval of about 8 years (range 4–21 years). Both examinations were performed after exposure cessation (median: surgery, 9.5 years; autopsy, 22 years). Pulmonary asbestos fibre burden was stable between both examinations (median 1623/4269 asbestos bodies per gram wet lung). Electron microscopy demonstrated a preponderance of chrysotile (median 80%).This study is the first to present longitudinal intra-individual data about the asbestos fibre burden in living human lungs. The high biopersistence of amphiboles, but also of chrysotile, offers mechanistic explanations for fibre toxicity, especially the long latency period of asbestos-related diseases.