# Mineral Fibres and Asbestos Bodies in Human Lung Tissue: A Case Study
## 4 Conclusions  
Our investigation provides new insights into the activity of asbestos in the human lung and proves that amphibe fibres can persist unaltered (showing just a thin amorphous coating) in the lung tissue for a lifetime. On the other hand, chrysotile fibres undergo dissolution, with Mg release and production of amorphous silica-rich remnants. In this study, the overall crystallinity of crocidolite fibres has been verified. In a separate study [74], synchrotron nano-diffraction data have shown that amosite fibres recovered from the lungs of the subject investigated here preserve the original atomic distribution in the crystal structure after 40 y of residence in the lungs. Here, 75% of the mineral fibres (coated and non-coated fibres) were longer than 5 um and thinner than 0.4 um. All fibres displayed an aspect ratio greater than 3:1, and 31% were coated with ABs. ABs consist of a mixture of Fe-containing proteins (ferritin and hemosiderin), goethite and apatite. ABs apparently nucleate only at the surface of fibres longer than 10 um and thinner than 0.5 um. These fibres display L and W values that are very close to the \"Stanton-size parameters\" (L > 8 um and W < 0.25 um) and they eventually lead to frustrated phagocytosis and chronic inflammation in the alveolar space. The fibre-coating process represents the exocytotic activity of macrophages aimed at the isolation of these fibres by deposition of ferroproteins (e.g., ferritin) onto the fibre surface. The occurrence of goethite in mature ABs attests to the alteration of ferrihydrite inside the ferritin, to the degradation of the protein shell, and to exposure of its iron core. This phenomenon can possibly lead to the release of \"safely stored iron\" in the extracellular space and may induce an Fe-mediated ROS activation. The following are available online at [[http://www.mdpi.com/2075-163X/9/10/618/s1](http://www.mdpi.com/2075-163X/9/10/618/s1)]([http://www.mdpi.com/2075-163X/9/10/618/s1](http://www.mdpi.com/2075-163X/9/10/618/s1)), Figure S1: Results of the stability test carried out on a mineral particle during an TEM investigation. Stability tests were performed by observing the same ROI for 2 min. After 2 min under the electron beam of the microscope, the crystalline structure of the mineral particle remains unaltered, and there is no formation of an amorphous phase at the particle edges. (a) Whole picture of the mineral particle. (b) HRTEM image of the mineral particle after 2 min under the electron beam, showing a highly crystalline structure (red square is the ROI). Figure S2: (a) SEMimage of non-coated amosite fibre found in the lung tissue of the male subject. SEM image was acquired using the signal of secondary electrons. Fibre is surrounded by residues of incomplete ashing. (b) SEM-EDX spot analysis (white star) of amosite shown in Figure S2a. (c) HRTEM micrograph of an individual non-coated crocidolite fibre found in the lung tissue of the male subject. Crocidolite fibre exhibits a thin amorphous layer on its surface. Red arrows and red lines highlight the amorphous layer. (d) FFT pattern extracted from HRTEM image shown in S2c, where the red square represents the region of interest. The d-spacings (A) and the angle determined from the pattern are: \([010]\) = 17.8 A, \([001]\) = 5.3 A, and \(\alpha\) = 90\({}^{\circ}\). Calculated cell parameters are consistent with the data for the South-African crocidolite (RRUEF ID = R0600228) [39]. Figure S3: (a) HRTEM micrograph of partially-coated crocidolite fibre found in the lung tissue of the male subject. Red arrows highlight the ABs segments (b) FFT pattern of the crocidolite fibre shown in Figure S3a, where the red square is the region of interest. The d-spacings (A) and the angle determined from the pattern are: \([010]\) = 17.7 A, \([001]\) = 5.3 A, and \(\alpha\) = 90\({}^{\circ}\). [PERSON] and [PERSON] conceptualised the research project. [PERSON], [PERSON], [PERSON], [PERSON] and [PERSON] designed the study and analysed the data. [PERSON] and [PERSON] carried out SEM analyses.