Environmental asbestos contamination in an abandoned chrysotile mining site: the example of Val Malenco (central Alps, northern Italy)

The Valmalenco area (central Alps, northern Italy) is well-known for the widespread mining and quarrying activities. Serpentinites are extracted and processed as valuable dimension stone in open-cast quarries, and a big underground mine provides talc as industrial mineral. The presence of long-fiber chrysotile veins, especially in the eastern part of the valley, gave rise in the past to widespread mining activity, particularly between the end of the XIX century and 1975, leaving huge amounts of mining waste and tailings. In recent times, part of the tailings have been stabilized and reclaimed, covered with soil and planted. Extensive sampling of mine tailings, soils and alluvial sediments was performed, to detect asbestos contamination (XRPD, SEM-EDS, TEM). Airborne asbestos was measured by environmental monitoring on polycarbonate filters (SEM and TEM), at the abandoned mines and at the closest centers. Huge amounts of chrysotile are still present in mine tailings (up to 20 wt.%), whereas soils and sediments were mostly below the 1000 ppm threshold; chrysotile is widespread almost in every part of the valley. Small amounts (< 400 ppm) of asbestiform tremolite were detected. Airborne asbestos was below the PEL of 2ff/l for living environments, with some peaks at mine dumps and close to active serpentine quarries. This preliminary study provides useful tips and effective technical measures for risk reduction in the extractive context.