Airborne concentrations of chrysotile asbestos in serpentine quarries and stone processing facilities in Valmalenco, Italy

Our plain-English summary of Airborne concentrations of chrysotile asbestos in serpentine quarries and stone processing facilities in Valmalenco, Italy, by A. Cattaneo, A. Somigliana, M. Gemmi, et al (The Annals of Occupational Hygiene, 2012).

The study

• Authors: A. Cattaneo, A. Somigliana, M. Gemmi, F. Bernabeo, D. Savoca, D.M. Cavallo, P.A. Bertazzi
• Journal: The Annals of Occupational Hygiene
• Published: 2012;56(6):671-83
• Cited by: 16 articles, as counted by NIH iCite
• Read it: PubMed · Publisher

Abstract

Asbestos may be naturally present in rocks and soils. In some cases, there is the possibility of releasing asbestos fibres into the atmosphere from the rock or soil, subsequently exposing workers and the general population, which can lead to an increased risk of developing asbestos-related diseases. In the present study, air contaminated with asbestos fibres released from serpentinites was investigated in occupational settings (quarries and processing factories) and in the environment close to working facilities and at urban sites. The only naturally occurrence of asbestos found in Valmalenco area was chrysotile; amphibole fibres were never detected. An experimental cut-off diameter of 0.25 μm was established for distinguishing between Valmalenco chrysotile and antigorite single fibres using selected area electron diffraction analyses. Air contamination from chrysotile fibres in the examined occupational settings was site-dependent as the degree of asbestos contamination of Valmalenco serpentinites is highly variable from place to place. Block cutting of massive serpentinites with multiple blades or discs and drilling at the quarry sites that had the highest levels of asbestos contamination generated the highest exposures to (i.e. over the occupational exposure limits) asbestos. Conversely, working activities on foliated serpentinites produced airborne chrysotile concentrations comparable with ambient levels. Environmental chrysotile concentrations were always below the Italian limit for life environments (0.002 f ml(-1)), except for one sample collected at a quarry property boundary. The present exposure assessment study should encourage the development of an effective and concordant policy for proper use of asbestos-bearing rocks and soils as well as for the protection of public health.

In plain English

This study measured airborne asbestos during quarrying and processing of serpentinite stone in Valmalenco, Italy. The authors took personal and fixed-site air samples at five quarrying sites (A to E) and at facilities processing their stone, plus ambient samples near facility boundaries and in nearby towns. Of 111 samples, 105 were valid. Only chrysotile and antigorite fibres were detected; amphibole fibres were not present. Mean chrysotile concentrations were 0.0265 fibres per ml during extraction (40 samples), 0.0971 during processing (43 samples) and 0.0005 in ambient air (22 samples). Site E gave the highest levels, and multi-blade cutting gave the highest activity mean (0.3110 fibres per ml). The results report that 7 of 83 occupational samples exceeded the 0.1 fibres per ml occupational limit, but the discussion gives six. The authors said five were fixed-site samples in enclosed cutting areas where workers need not be present. Work on foliated serpentinite stayed below 0.004 fibres per ml. One ambient sample, at a quarry boundary, exceeded the Italian 0.002 fibres per ml limit. The authors concluded that contamination was site-dependent.

We wrote this plain-English summary from the full article with the help of AI, and a second AI model checked each sentence against the article. It is not the authors' wording; the abstract and the article are their own account.

What the study did and found

• Design: Exposure assessment study using personal and fixed-site (static) air sampling at work activities, plus ambient air sampling; fibres counted by scanning electron microscopy and identified with transmission electron microscopy and electron diffraction
• Who was studied: Five serpentinite quarrying sites (A to E) and the facilities processing their stone in Valmalenco, northern Italy, plus nearby towns. Of 111 samples, 6 were discarded, leaving 83 valid occupational samples (40 during extraction, 43 during processing) and 22 valid ambient samples. Sampling dates are not stated.
• Exposure: Chrysotile asbestos released from serpentinite rock. Quarrying activities were wet drilling, dry drilling and string cutting. Processing activities were multi-blade cutting, multi-disc cutting, monodisc cutting, dry finishing, and manual splitting of foliated serpentinite.
• Main results:
  • Only chrysotile and antigorite fibres were found in the air samples; amphibole fibres were not present.
  • Under transmission electron microscopy, 74 of 96 serpentine fibres were chrysotile. A diameter cut-off of 0.25 micrometres was proposed to tell single chrysotile fibres from antigorite fibres in Valmalenco samples.
  • Mean chrysotile concentration was 0.0265 fibres per ml (median 0.0023) in 40 extraction samples, 0.0971 (median 0.0047) in 43 processing samples and 0.0005 (median 0.0003) in 22 ambient samples. The difference between processing and quarry levels had a p-value of 0.086.
  • Site E had the highest mean occupational chrysotile concentration: 0.4488 fibres per ml in 9 samples. Site C had 0.0012 in 10 samples. For quarrying activities alone, post-hoc tests found no significant differences between sites.
  • Multi-blade cutting (12 samples, all fixed-site) had the highest mean of any activity, 0.3110 fibres per ml.
  • The results report that 7 of 83 occupational samples (about 8%) exceeded the 0.1 fibres per ml occupational limit. During processing, five of six exceedances occurred during indoor block cutting with multi-blade or multi-disc cutters. At the quarries, the one exceedance was in a worker's breathing zone during wet drilling at Site E.
  • The discussion gives six of 83 samples (7%) over the limit. It says five of these were fixed-site samples in enclosed areas where workers need not be present, and notes that occupational limits are 8-hour time-weighted averages.
  • All 10 samples taken during extraction and processing of foliated serpentinite (typical of Area C) were below 0.004 fibres per ml.
  • The Italian environmental limit of 0.002 fibres per ml was exceeded at one location next to a quarry property boundary. The discussion places it in Area C and links it to dust from truck traffic on a dirt road.
• The authors' conclusion: The authors concluded that asbestos air contamination in Valmalenco serpentinite quarrying and processing was site-dependent. In their view, block cutting with multiple blades or discs and drilling at the most contaminated quarry sites produced the highest exposures (over the occupational limit). Work on foliated serpentinite gave levels comparable with ambient air, and ambient levels were below the Italian limit except for one quarry-boundary sample.
• Limitations the authors state:
  • Few samples were taken during dry drilling because it is an unusual activity, and dry drilling was not monitored at Site E, the most contaminated site.

Topics

The National Library of Medicine indexes this study under subjects our site covers: Chrysotile.

Medical terms in this study, explained in our Lexicon: Chrysotile, Serpentine Group, Serpentinite, Amphibole Group, Antigorite, Selected Area Electron Diffraction (SAED), Occupational Exposure.

Related studies

• Chrysotile asbestos in serpentinite quarries: a case study in Valmalenco, Central Alps, Northern Italy — A. Cavallo, B. Rimoldi (2013)
• A comparison of parallel dust and fibre measurements of airborne chrysotile asbestos in a large mine and processing factories in the Russian Federation — E. Feletto, S.J. Schonfeld, et al. (2017)
• A study of airborne chrysotile concentrations associated with handling, unpacking, and repacking boxes of automobile clutch discs — G.C. Jiang, A.K. Madl, et al. (2008)
• Airborne concentrations of chrysotile asbestos during operation of industrial crane controls and maintenance of associated arc chutes — M.J. McCoy, R.C. Lewis, et al. (2021)
• Occupational cohort study of current and former workers exposed to chrysotile in mine and processing facilities in Asbest, the Russian Federation: Cohort profile of the Asbest Chrysotile Cohort study — J. Schüz, I. Bukhtiyarov, et al. (2020)
• Airborne asbestos concentration from brake changing does not exceed permissible exposure limit — C.L. Blake, D.R. Van Orden, et al. (2003)

Browse more research in The Annals of Occupational Hygiene, or return to medical research.