Environmental scanning electron microscopy technique to identify asbestos phases inside ferruginous bodies

Asbestos exposure diagnosis in pulmonary tissues

The diagnosis of asbestosis requires different criteria depending on whether it is in a clinical or medical/legal setting. In the latter context, only when a "diffuse interstitial fibrosis associated to asbestos bodies (ABs)" is present, it can be said to be asbestosis. Considering the medical/legal setting, the diagnosis must be certain and proven. Unfortunately, it is often difficult to identify ABs by light microscopy (LM), but this does not mean that the diagnosis should be clinically excluded. Other parameters are important, such as working history and/or diagnostic imaging. In addition to LM, normally used for diagnosis, there are other techniques, e.g.: scanning electron microscopy with attached microanalysis microprobe (SEM/EDS), but they require tissue digestion and higher cost. A new approach with micro-Raman spectroscopy and SEM/EDS techniques is able to analyse histological sections without other manipulations that could interfere with analysis of asbestos fibres. In this work, we propose an algorithm for asbestosis diagnosis, especially in the forensic medical field, demonstrating the importance of close collaboration between multiple professionals.

Closing the knowledge gap on the composition of the asbestos bodies

Asbestos bodies (AB) form in the lungs as a result of a biomineralization process initiated by the alveolar macrophages in the attempt to remove asbestos. During this process, organic and inorganic material deposit on the foreign fibers forming a Fe-rich coating. The AB start to form in months, thus quickly becoming the actual interface between asbestos and the lung tissue. Therefore, revealing their composition, and, in particular, the chemical form of Fe, which is the major component of the AB, is essential to assess their possible role in the pathogenesis of asbestos-related diseases. In this work we report the result of the first x-ray diffraction measurements performed on single AB embedded in the lung tissue samples of former asbestos plant workers. The combination with x-ray absorption spectroscopy data allowed to unambiguously reveal that Fe is present in the AB in the form of two Fe-oxy(hydroxides): ferrihydrite and goethite. The presence of goethite, which can be explained in terms of the transformation of ferrihydrite (a metastable phase) due to the acidic conditions induced by the alveolar macrophages in their attempt to phagocytose the fibers, has toxicological implications that are discussed in the paper.

Asbestos fiber identification in liver from cholangiocarcinoma patients living in an asbestos polluted area: a preliminary study

PURPOSE

To assess whether asbestos fibers may be observed in liver tissue of patients with cholangiocarcinoma (CC) with environmental or working asbestos exposure.

METHODS

Detection of fibers was performed directly on histologic sections of liver from 7 patients with CC using optical microscope and variable pressure scanning electron microscopy equipped with energy-dispersive spectroscopy (VP-SEM/EDS). All patients were from Casale Monferrato, Italy, a highly asbestos-polluted town. Due to ethical constraints, observers were blinded to patients' clinical features.

RESULTS

Fibers/bundles of fibers of chrysotile were detected in 5 out of 7 patients (71%). The boundary between healthy and neoplastic tissue or the fibrocollagen tissue produced by the neoplasia were identified as areas of fiber incorporation.

CONCLUSIONS

This study is the first report about the detection of chrysotile asbestos fibers in the liver of patients with CC. Further studies on larger cohorts are needed to corroborate our preliminary findings.

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.

Asbestos fibres detected by scanning electron microscopy in the gallbladder of patients with malignant pleural mesothelioma (MPM)

Gallbladders from patients affected by both malignant pleural mesothelioma (MPM) and important gallbladder disorders were analyzed to verify the presence of asbestos fibres. Histological thin sections were analyzed by optical microscope and variable pressure scanning electron microscopy coupled with energy dispersive spectroscopy, allowing morphological and chemical characterization of each inorganic phase observed. Fibres of chrysotile and crocidolite, minerals regulated as asbestos, were identified. By immunohistochemical analysis, connective tissue was recognized as the incorporation site. These findings confirm that asbestos fibres can reach the gallbladders of patients with MPM, for whom the development of respiratory diseases confirms asbestos exposure.

Asbestos fibers in the gallbladder of patients affected by benign biliary tract diseases

PURPOSE

This exploratory study aimed to evaluate the presence of asbestos fibers in the biliary tract of patients living in an asbestos-polluted area using scanning electron microscopy.

METHODS

Thin gallbladder sections were obtained from five patients who were operated on for gallbladder stones and the bile fluid of one of the patients was analyzed using variable-pressure scanning electron microscopy coupled with energy-dispersive spectroscopy. All patients were from Casale Monferrato, Italy, a well-known asbestos-polluted city, where the Eternit factory had operated since the beginning of the century until 1985.

RESULTS

All the inorganic phases found in the gallbladder were analyzed for morphology and chemistry. Fibers and particles consistent with minerals defined by law as 'asbestos' were detected in three out of five patients.

CONCLUSION

These findings suggest that asbestos fibers can be found in the gallbladder of patients exposed to asbestos, although how they reach the biliary tract remains unknown. Further studies to confirm these results are under way.