Asbestos fibre burden in gallbladder: A case study.

The methods conventionally used to determine the burden of asbestos fibres inhaled/incorporated in lung require chemical digestion of the biological matrix before counting/characterising the inorganic fibrous phases under scanning electron microscopy and energy dispersive spectroscopy (SEM/EDS). Asbestos fibres can also be present in extra-pulmonary organs, and we set out to quantify the fibres in gallbladder. Although the standardised procedure requires approximately 5 × 10-1 g of wet tissue, this amount of tissue is not always available. We applied the procedure on about 9 × 10-4 g of gallbladder from a patient with known environmental and workplace exposure to asbestos. The patient died of malignant pleural mesothelioma and was also affected by severe bile-tract problems. The traditional procedure of digesting tissue samples in NaClO and filtering the resulting suspension was carried out. The filter was then examined under SEM/EDS using two methods 1. following the standardised procedure to assess the fibre burden in lung by investigating only 2 mm2 of the filter (660 microscopic fields), and 2. analysing all the microscopic fields in one-quarter of the filter (about 82 mm2). In parallel, histological sections (prepared in the usual way for medical diagnosis) were analysed without digestion or manipulation of the sample using variable pressure SEM/EDS. The fibre counts obtained using the two methods were of the same order of magnitude, i.e., ∼105 fibres/g of wet tissue. We showed that the counting of fibres in human tissue may be successfully carried out even when a limited amount of tissue is available. We also found that, when exposure to asbestos is considerable, the number of asbestos fibres accumulating in the gallbladder may be significant.

Assessment of cancer risks due to environmental exposure to asbestos.

In a rural area widespread pollution of friable and non-friable waste products was present, used to harden dirt tracks, yards, and driveways during 1935-1974. Exposure to environmental asbestos was assessed by a site approach, based on number of polluted sites within postal code areas, and by a household approach, based on number of households in the close vicinity to polluted sites within postal code areas. Based on asbestos soil investigations, 293 sites were identified with asbestos waste material at the surface, of which 77% contained crocidolite fibres as well as chrysotile fibres. The 293 sites-at-risk varied from 5 m(2) to 2722 m(2) and were surrounded by 347 households within 100 m of these sites. Distance to the plant was associated with the number of sites (r=0.36), and with the number of households (r=0.52). However, categorization of postal code areas into low, intermediate or high likelihood of exposure to asbestos showed a modest agreement between the site and household approach. In the site approach a total of 2.3 million person-years at risk were estimated with an average exposure of 1674 fibres/m(3) and an expected 1.8 cases of malignant mesothelioma each year. The household approach resulted in estimates of 1.2 million person-years at risk, and 0.9 cases of malignant mesothelioma per year, respectively. This study illustrates that asbestos waste on the surface of roads and yards in an area with over 130,000 inhabitants may result in long-term exposure to asbestos that will cause several cases of malignant mesothelioma each year. Although distance to plant, number of polluted sites and number of exposed household were associated, the modest agreement among these measures of exposure indicate that the exposure assessment strategy chosen in a particular study may result in considerable misclassification. Without detailed information on individual behaviour within the polluted area, it is difficult to show that a more individually oriented approach will perform better than an ecological approach.

Desmoplastic malignant mesothelioma of the pleura: autopsy reveals asbestos exposure.

Desmoplastic mesothelioma is a rare subtype of diffuse malignant mesothelioma, and is often difficult to distinguish from reactive pleural fibrosis because of associated extensive collagen fibrosis. An 82-year-old woman with a severe cough was revealed to have pleural effusion and diffuse pleural thickening on the right side. Antibiotics were ineffective, and a compression fracture of the ninth and tenth thoracic vertebral bodies was recognized on X-ray. Autopsy revealed a diffuse pleural thickening with hyalinized collagen tissue in the central part of the pleura. However, the peripheral part of the fibrous tissue was composed of spindle and polygonal cell proliferation that were immunohistochemically positive for antibodies against cytokeratin and vimentin. In addition, the ninth and tenth thoracic spines were infiltrated by similar cells. The condition was diagnosed as desmoplastic mesothelioma with bone metastases. Asbestos bodies were detected in the thickened pleura and fibrosed alveolar septa, and it was suggested retrospectively that the patient had been exposed to asbestos. Thus, autopsy analyses of fibrous pleurisy are necessary to detect a desmoplastic variant of mesothelioma of the pleura and its association with asbestos exposure.