Worker’s asbestos exposure in quarrying and processing of the “Serpentino della Val Malenco”, Central Alps, Italy: risk assessment and prevention

The “Serpentino della Valmalenco”, derived from the Malenco massif (Central Alps, Sondrio) is a well known serpentinitic dimension and building stone, exploited since the XI century, now widespread and appreciated worldwide. There are about 15 active quarries in the valley, that produce altogether 70000 m3/yr of serpentinites (“massive” and schistose commercial varieties), with more than 30 enterprises performing both quarrying and processing. Evaluation of worker’s airborne asbestos exposure was required, both in quarries and in processing laboratories, according to the Italian laws M. D.14/05/09 (“Pietre Verdi”) and Lgs. D. 81/08, because of quarrying activities interference with non-commercial chrysotile asbestos veins. INAIL and the University of Milano-Bicocca collected more than 500 samples (both massive rock/veins and airborne dust) during the 2005-2009 surveys. Personal and environmental airborne samples were analyzed by means of phase-contrast microscopy (PCM) and SEM-EDS at the INAIL-CONTARP laboratories, whereas the massive samples were collected and studied in the laboratories of the University of Milano-Bicocca (SEM-EDS, XRPD, PLM, FT-IR). The assessed exposure levels were mainly below the OEL (occupational exposure limit, 0.1 ff/cm3), except for sporadic and localized cases. The critical factors in airborne asbestos evaluation were the correct dust amount on the filters (depending on quarrying or processing activity) and the distinction between chrysotile asbestos and fibrous antigorite splinters. Field surveys, geostructural mapping (fracture/vein geometry, opening and filling) and sampling in quarries proved to be essential in forecasting chrysotile veins in quarry front prosecution. The analysis performed on massive rock or veins samples highlighted the analytical problem in detecting low level asbestos contents in serpentinitic rocks, and the need of a electronic microscope approach. The collected results represent an essential tool for the actions of the surveillance authorities and the technical and scientific basis for preventive measures, in the context of the Operative Agreement INAIL – Regional Local Authority of Lombardia. This item has the aim to describe the planning and the implementation of the synergic collaboration among Institutions, Local Authorities and enterprises in order to improve occupational health and safety and risk prevention of the mining industry.