Risk assessment of the decay of asbestos cement roofs

Our plain-English summary of Risk assessment of the decay of asbestos cement roofs, by A. Campopiano, D. Ramires, A.M. Zakrzewska, et al (The Annals of Occupational Hygiene, 2009).

The study

• Authors: A. Campopiano, D. Ramires, A.M. Zakrzewska, R. Ferri, A. D'annibale, G. Pizzutelli
• Journal: The Annals of Occupational Hygiene
• Published: 2009;53(6):627-38
• Cited by: 10 articles, as counted by NIH iCite
• Read it: PubMed · Publisher

Abstract

Objectives: In an assessment of the risk of asbestos fibres release from asbestos cement materials, an important role is played by the assessment of the surface corrosion and by the disaggregation of asbestos cement. The aim of this work is to evaluate the differences among several methods used for the risk assessment that lead to a specific choice of abatement techniques.

Methods: The state of deterioration of 40 asbestos cement roofs was evaluated using two priority assessment algorithms elaborated in Italy, the 'pull-up test' described by the Italian Organization for Standardization and the indicators described in the Italian legislation coupled with the observation of a small sample, taken from each roof, by a stereomicroscope.

Results: The results obtained with the methods, proposed in this study, for the risk assessment of the decay of asbestos cement roofs show slight differences among them, only one deviates from the others in judgement on the state of conservation of the roof.

Conclusions: It is very important to train the operator conducting the study since a completely subjectivity-free method does not exist. Whatever method is used will always be affected by the subjectivity linked to the competency and the training of the operator. Moreover, each method on its own cannot assess the risk of exposure to asbestos, but reliable assessment of asbestos-containing materials requires the use of more than one method, such as visual inspections, a pull-up test, and an assessment algorithm.

In plain English

This study compared methods for judging the deterioration of asbestos cement roofs. The authors assessed roofs on 40 buildings with four methods. These were two Italian scoring systems (A and B algorithms), a 'pull-up' adhesive-tape test, and indicators from a 1994 Italian decree with stereomicroscope examination. The authors reported only slight differences among the methods, except for the B algorithm. It rated 57% of roofs 'poor'. The authors said the A algorithm marked almost all of these for removal, but their table marks 12 of the 23 for removal and 11 for encapsulation. The A algorithm never scored a roof low enough to be left untreated. The authors found the pull-up test fairly in agreement with it. Mean airborne asbestos levels beside 20 buildings ranged by building type from 0.0 fibres per litre (95% confidence limits 0.0 to 0.4) at public buildings to 0.6 (0.2 to 1.4) at disused industrial sites. All airborne asbestos fibres found were chrysotile. The authors concluded that no method is free of operator subjectivity and that several methods should be combined.

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: Field comparison of methods for assessing the deterioration of asbestos cement roofs, with air sampling near some of the buildings
• Who was studied: Asbestos cement roofs on 40 buildings (public, agricultural and industrial), assessed using Italian methods; air sampling was done near 20 of the buildings; study dates not given
• Exposure: Weathered asbestos cement roofing sheets; amosite and chrysotile fibres were identified by electron microscopy in material lifted by the pull-up test
• Main results:
  • The B algorithm classified 57% of the roofs as poor. The authors stated that almost all of the same roofs were rated high risk, to be removed, by the A algorithm. However, Table 3 marks only 12 of the 23 B-'Poor' roofs 'Remove' and the other 11 'Encapsulate'.
  • The A algorithm never gave any roof a score below 26, the maximum score at which material could be left without treatment
  • The authors found the pull-up test fairly in agreement with the A algorithm
  • In tape material from roofs classed 'very poor' by the pull-up test, the asbestos fibres were completely free of the cement
  • Mean airborne asbestos concentrations near the buildings, in fibres per litre with 95% confidence limits: farms (5 buildings, 13 samples) 0.4 (0.1 to 1.0); industrial sheds (4 buildings, 10 samples) 0.4 (0.1 to 1.0); repair shops (2 buildings, 4 samples) 0.4 (0.1 to 1.0); industrial disused sites (7 buildings, 30 samples) 0.6 (0.2 to 1.4); public buildings (2 buildings, 6 samples) 0.0 (0.0 to 0.4)
  • The authors described the airborne levels as low and comparable with WHO reference values for urban areas, despite heavy roof deterioration
  • All airborne asbestos fibres found by SEM analysis were chrysotile; no airborne amphibole fibre was detected
• The authors' conclusion: The authors concluded that no single method can assess the risk of asbestos exposure on its own, and that combining visual inspection, the pull-up test and the A algorithm gives a reliable assessment
• Limitations the authors state:
  • Every method is affected by the subjectivity, competence and training of the operator
  • One A-algorithm item (surface release onto a rubbed latex glove) is very hard to judge visually
  • An air sample reflects only the time of sampling and gives no information about earlier fibre release
  • The gutter-material indicator depends on recent weather; heavy rain can remove the material

Topics

Medical terms in this study, explained in our Lexicon: Asbestos-Cement, Abatement, Asbestos-Containing Material (ACM).

Related studies

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• Occurrence, spatial distribution, seasonal variations, potential sources, and inhalation-based health risk assessment of organic/inorganic pollutants in ambient air of Tehran — M. Kermani, Z. Asadgol, et al. (2021)
• Monitoring of airborne asbestos fibers in an urban ambient air of Shahryar City, Iran: levels, spatial distribution, seasonal variations, and health risk assessment — F. Taghizadeh, A.J. Jafari, et al. (2019)
• Asbestos Exposure Level and the Carcinogenic Risk Due to Corrugated Asbestos-Cement Slate Roofs in Korea — E.S. Lee, Y.K. Kim (2021)
• Asbestos fibre burden in the lungs of patients with mesothelioma who lived near asbestos-cement factories — P.G. Barbieri, D. Mirabelli, et al. (2012)

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