Exposure to Amosite-Containing Ceiling Boards in a Public School in Switzerland: A Case Study
1.2. Context of the Study
2. Materials and Methods
2.2. Study Population
2.3. Exposure Scenarios
2.4. Exposure Concentrations
- In situ measurements, according to the German norm VDI 3492:2013, were performed to assess ambient concentrations, and events-related concentrations associated with regular maintenance activities (e.g., changing a neon lamp in the ceiling board).
- Laboratory measurements were performed in an 8 m3 enclosed booth to assess events-related concentrations of potentially high emission (e.g., the fall or breakdown of a ceiling board). Concentrations in the classrooms were estimated, using IH Mod tool version 0.212 , and assuming a one-box dilution model.
- Previous technical data, issued from the Evalutil database  or reports issued from institutional bodies, was used when the two first methods were inappropriate.
- Monte-Carlo simulations have been conducted, using Stata IC 14.2 (StataCorp LP, 4905 Lakeway Drive College Station, TX, USA) in order to assess the maximal background concentration.
2.5. Dose-Response Model
- The risk calculation has been adjusted taking into account the life expectancy in the Swiss population . As the incidence of IM tends to increase with age and the pathology often manifests itself late, the life expectancy of the population concerned plays an important role in calculating the whole-life risk.
3.1. Exposure Scenarios
3.2. Exposures Concentrations
3.3. Background Exposure
3.4. Events-Based Exposures
3.5. Risk Assessment
- Exposure estimates are based on a limited number of recent measurements, and thus not necessarily representative of past exposures and subject to uncertainties.
- The dose-response models available for asbestos have been built on cohorts of adult workers highly exposed to asbestos fibers. Extrapolation to low doses in the general population is therefore a source of uncertainty.
Conflicts of Interest
Appendix A.1. Exposure Concentrations
- In situ measurements. Asbestos air measurements were performed in accordance with the method VDI 3492:2013 (The reference method in Switzerland (VDI 3492:2013) is based on Scanning Electron Microscopic (SEM). Transmission Electron Microscopy (TEM), which has a better performance for small and thin fibers, has been adopted in several countries. No count differences are expected however for amosite fibers to their relative thickness and length.) Ambient measurements, reflecting the regular use of the building, were performed in classrooms and corridors at the end of the week. Events-related measurements associated with regular maintenance activities (e.g., changing a neon lamp in the ceiling board), were performed in classrooms that were isolated prior to the asbestos removal. It should be noted that for practical reasons, event-related measurements were often performed using sampling times shorter than the regular 8-h (typically 4 h).
- Laboratory measurements. Events-related measurements of potentially high emission (e.g., the fall or breakdown of a ceiling board) were performed in the laboratory of the Institute of Work and Health (IST). The emitting events were simulated in an 8 m3 enclosed booth in which air movements were induced using a portable fan. The sampling time was of 1, h hour after the simulated event. Concentrations in the classrooms were estimated by computing the fibers emission rate related to the event and using a one-box model to assess the corresponding concentration in the classrooms. A volume of 140 m3 with an air renewal of 0.5–1 [h−1] was used to represent an average sized classroom with a poor ventilation. Computations were performed using IH Mod tool version 0.212 (AIHA, Falls Church, VA, USA) .
- Use of technical data. Three sources of exposure data were considered in this study: the Evalutil database , results from a measurement campaign conducted by National Research and Safety Institute for occupational accidents prevention in France (INRS, 2011), as well as measurements results issued from the Cantonal Service for Industrial Toxicology and Protection against Indoor Pollution, Geneva, Switzerland. Although the latest was unpublished material, it was considered as highly relevant because it involved ceiling-boards similar to the ones identified in this study.
- Monte-Carlo simulations was used, using Stata IC 14.2 (StataCorp LP, College Station, TX, USA) in order to assess the maximal background concentration.
Appendix A.2. Background Estimate through Monte Carlo Simulation
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|Population||Scenario||First Exposure Age (yr.)||End Exposure Age (yr.)||Comment|
|pessimistic 1||6||17||repetition of two years, asbestos-contaminated boards in each classroom|
|pessimistic 2||6||17||scenario pessimistic 1 + unusual exposure each year (e.g., fire remediation) (1)|
|pessimistic 1||25||54||highest duration and weekly hours in the building among the respondents|
|pessimistic 2||25||54||scenario pessimistic 1 + unusual exposure each year (e.g., fire remediation) (1)|
|pessimistic 3||25||65||scenario pessimistic 2 + whole worklife exposure (hypothetical scenario)|
|pessimistic 1||20||60||whole worklife exposure (hypothetical scenario)|
|Description||Population||Average Scenario||Pessimistic Scenario|
|Event||Pupils||Teachers||Janitor||Concentration (F/m3)||Event Duration (h)||Event Frequency (yr−1)||Contribution to the Yearly Dose1 (F/m3)||Event Duration (h)||Event Frequency (yr−1)||Contribution to the Yearly Dose (F/m3) (1)|
|Background indoor exposure (regular use of the building)||●||75||940||0.5||18||1200||1.0||47|
|Hitting a board (incident)||●||●||●||1000||4||19.0||40||4||38.0||79|
|Board replacement (regular maintenance)||●||50,000||0.25||2.5||16||0.25||5.0||33|
|Lamp replacement (regular maintenance)||●||20,000||0.17||37.5||65||0.17||75.0||130|
|Board replacement (regular maintenance)||●||●||400||4||0.06||0.05||4||0.13||0.10|
|Lamp replacement (regular maintenance)||●||●||200||4||0.94||0.39||4||1.9||0.78|
|Cutting/adjusting a board||●||9000||n.a||n.a||n.a||0.1||5||0.83|
|Breaking a board (incident)||●||●||●||5500||4||0.01||0.14||4.0||0.03||0.29|
|Fall (incl. breaking) of a board (incident)||●||●||●||10,500||4||0.01||0.27||4.0||0.03||0.55|
|Remediation work after a fire (incident)||●||1000||50.0||1.00||26.04|
|Population||Scenario||Av. Yearly Exposure conc. F/m3||ER Mesothelioma||ER Lung Cancer|
|Pupils||average||59||5.5 × 10−6||4.0 × 10−7|
|pessimistic (1)||128||1.4 × 10−5||1.0 × 10−6|
|pessimistic (2)||155||1.7 × 10−5||1.2 × 10−6|
|Teachers||Average||52||1.8 × 10−6||3.0 × 10−7|
|pessimistic (1)||140||8.7 × 10−6||2.7 × 10−6|
|pessimistic (2)||170||1.06 × 10−5||3.3 × 10−6|
|Janitor||Real||200||6.8 × 10−6||2.0 × 10−6|
|pessimistic (1)||320||2.97 × 10−5||8.3 × 10−6|
|ER||Chrysotile only KM 0.15 10−8||Mix (Chrysotile + Amphibole) KM 1.3 10−8||Amosite only KM 3.9 10−8||Amphiboles (Amosite + Crocidolite) KM 7.95 10−8||All Fibers Kl 1.64 10−2|
|4 × 10−3||1,122,832||129,578||43,211||21,186||155,262|
|1 × 10−4||27,996||3230||1077||528||3871|
|4 × 10−5||11,198||1292||431||211||1549|
|1 × 10−5||2799||323||108||53||387|
|1 × 10−6||280||32||11||5||39|
|1 × 10−4||55,424||6395||2132||1046||28,814|
|1 × 10−5||5542||639||213||105||2881|
|1 × 10−6||554||64||21||10||288|
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Vernez, D.; Duperrex, O.; Herrera, H.; Perret, V.; Rossi, I.; Regamey, F.; Guillemin, M. Exposure to Amosite-Containing Ceiling Boards in a Public School in Switzerland: A Case Study. Int. J. Environ. Res. Public Health 2019, 16, 5069. https://doi.org/10.3390/ijerph16245069
Vernez D, Duperrex O, Herrera H, Perret V, Rossi I, Regamey F, Guillemin M. Exposure to Amosite-Containing Ceiling Boards in a Public School in Switzerland: A Case Study. International Journal of Environmental Research and Public Health. 2019; 16(24):5069. https://doi.org/10.3390/ijerph16245069Chicago/Turabian Style
Vernez, David, Olivier Duperrex, Horacio Herrera, Vincent Perret, Isabelle Rossi, Frederic Regamey, and Michel Guillemin. 2019. "Exposure to Amosite-Containing Ceiling Boards in a Public School in Switzerland: A Case Study" International Journal of Environmental Research and Public Health 16, no. 24: 5069. https://doi.org/10.3390/ijerph16245069