Asbestos fate in ACM and lungs: a comparative characterization.

In 2006 it has been proposed to introduce the term of “nanosafety”. Nowadays, developments in nanotechnology grow increasingly, with the intention of new useful discoveries and the concern of possible health consequences, some of them have been already experienced by mankind since more than 100 hundred years. Among these health risks, asbestos cement was invented by Hatschek and patented under the name “Eternit” in 1900. Until now, this technologically exceptional material is used in many countries, however accepting the fatal health consequences created by the disease asbestos. It is evident that many protocols applied to the asbestos problem can be easily exploited to monitor these emerging technologies and new harmful mineral nanoparticle and fiber. From this perspective, we will analyze the fibers contained in two different matrices: the first type artificial and the second type organic. We have purposely avoided to gather information on the source material, not to influence our judgment or to address the analytical process, as if it were performed on an unknown material. In order to characterize the target materials, we combined different analytical techniques: XRPD, SEM and TEM. Handling the three, depending on what samples gradually reveals. A sample from an unknown fiber cement sheet roof was characterized, combining X-ray powder diffraction (XRPD), scanning electron microscopy (SEM) and transmission electron microscopy (TEM). The same was performed on a lung of a Eternit factory worker died of mesothelioma, using only TEM because of the sample nature (received already embedded in paraffin). To the naked eye the ACM sample present two principal component: the cement matrix and the fibrous component. A first investigation through XRPD reveals the possible presence of typical cement phases in the matrix. No fibrous phases has been identified at this point. Having a thought on the production process, we could imagine that the fibers presence in an XRD support is really low in relation to other components. Historically, in asbestos sheet, was recognized a percentage of fibers variable from 10 to 16, randomly distributed in the whole matrix. Moreover, the sample is heterogeneous powder, multiphase and randomly oriented, all factors that tend to hide the possibility to detect the fibrous component. SEM observation brings in evidence the presence of many fibers bundles distributed in the whole sample and in intimate contact with the matrix components. Going beyond with the TEM, it’s possible to identify the fibrous phase combining high resolution (HRTEM) techniques, bright field (BF) imaging and selected area electron diffraction (SAED). In a preliminary TEM investigation the specimen contained in the lung present partially and totally amorphized fibers, mainly of chrysotile and rare amphibole fibers. These fibers are more sensitive to the beam than the natural ones and seems to be covered by an amorphous shell that shows that the amorphization process starts from the surface and proceed through the core of the fiber.