Eugenio Barrese

Asbestos and other fibrous minerals contained in the serpentinites of the Gimigliano-Mount Reventino Unit (Calabria, S-Italy)

Serpentinites are metamorphic rocks with good technological properties and valuable ornamental characteristics, which have been exploited since ancient times. Actually, their use is limited and monitored in several countries worldwide because they can contain fibrous asbestos minerals that may be carcinogenic. Furthermore, certain types of fibrous minerals can be confused with asbestos, and must therefore be carefully investigated. We have investigated the possible presence of the asbestos and non-asbestos fibrous phases contained in serpentinitic rocks in a meta-ophiolitic sequence from the Gimigliano-Mount Reventino Unit (Southern Italy), which had not been previously assessed. The detection and quantification of asbestos and the correct distinction of the fibrous non-asbestos minerals are very important not only from a scientific point of view, but also from a legislative one. This is especially the case for the administrative agencies that have to take decisions with regards to the implementation of public and occupational health protection measures (e.g., in road yards and quarry excavations). As a consequence of this, serpentinitic rock samples have been characterized in detail through X-ray powder diffraction, scanning and transmission electron microscopy combined with energy-dispersive spectrometry, analytical electron microscopy (SEM–EDS and TEM–AEM), differential scanning calorimetry, thermogravimetry and micro-Raman spectroscopy. Two kinds of asbestos and four kinds of non-asbestos fibrous silicates have been detected in the examined samples. In order of decreasing abundance these are polygonal serpentine, chrysotile, fibrous antigorite, tremolite, gedrite and magnesiohornblende. The size, morphology, crystallinity and chemical composition of the fibres were also discussed, in the light of the possible role these properties could play in the carcinogenic effect on human health.

Synthesis and characterization of tremolite asbestos fibres

Fibres of Fe-free tremolitic amphibole were synthesized using hydrothermal conditions. The run products contained only minor amounts of one other phase, quartz, as determined by X-ray powder diffraction (XRPD). The fibrous material was characterized by scanning and transmission electron microscopies combined with energy dispersive spectrometry (SEM-EDS and TEM-EDS), differential scanning calorimetry (DSC), thermogravimetry (TG) and micro-Raman spectroscopy. The average length and width of the fibres, as determined by SEM and TEM on about 600 fibrils, fall within the definition of breathable fibres and potentially carcinogenic. Electron diffraction patterns of selected areas (SAED) from single fibres revealed a high crystallinity. Raman spectroscopy showed bands matching those observed on natural samples of tremolite. These synthetic and well-characterized fibres can be used in in vitro studies, where cell reactions to synthetic and natural tremolite fibres are compared.

Occurrence and characterization of asbestos minerals in the area of San Severino Lucano (Basilicata, Southern Italy)

Serpentinites are metamorphic rocks used for building and ornamental purposes since ancient times but they can contain asbestos minerals, thus currently their use is limited or banned in several countries. In this study we have investigated the possible presence of asbestos contained in the serpentinitic rocks outcropping near San Severino Lucano (Basilicata, Southern-Italy). Serpentinites have been characterized in detail combining different analytical techniques in order to detect asbestos minerals that maybe potentially harmful for human health.