An Australian stocks and flows model for asbestos

Our plain-English summary of An Australian stocks and flows model for asbestos, by S. Donovan, J. Pickin (Waste Management & Research, 2016).

The study

• Authors: S. Donovan, J. Pickin
• Journal: Waste Management & Research
• Published: 2016;34(10):1081-1088
• Cited by: 2 articles, as counted by NIH iCite
• Read it: PubMed · Publisher

Abstract

All available data on asbestos consumption in Australia were collated in order to determine the most common asbestos-containing materials remaining in the built environment. The proportion of asbestos contained within each material and the types of products these materials are most commonly found in was also determined. The lifetime of these asbestos containing products was estimated in order to develop a model that projects stocks and flows of asbestos products in Australia through to the year 2100. The model is based on a Weibull distribution and was built in an excel spreadsheet to make it user-friendly and accessible. The nature of the products under consideration means both their asbestos content and lifetime parameters are highly variable, and so for each of these a high and low estimate is presented along with the estimate used in the model. The user is able to vary the parameters in the model as better data become available.

© The Author(s) 2016.

In plain English

This paper described a spreadsheet model that estimated how much asbestos remained in Australia's built environment and when it would become waste, projected to 2100. It studied materials and waste, not disease. Using British Geological Survey records, the authors put total apparent asbestos consumption in Australia from 1920 to 2003 at 12.8 million tonnes. They divided this among product groups such as asbestos cement sheeting, cement water pipes, flooring, friction products and roofing, and estimated how long each lasted. In the best estimate, stocks peaked at 10.5 million tonnes in 1981. In 2016, 44% (5.6 million tonnes) remained in stock, and by 2055 10% would remain. Modelled asbestos waste peaked in 2004 at 170 thousand tonnes, although the conclusion section gives 2014. The authors noted that this modelled decline did not match landfill records, which showed an apparent recent upward trend. Results varied widely with the assumed product lifetimes, and the model could not tell asbestos fiber types apart. The authors concluded the model provides a first-order estimate.

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: Stocks and flows modelling study using a Weibull lifetime distribution, built in an Excel spreadsheet, with best, low and high estimates
• Who was studied: Asbestos stocks and waste flows for Australia as a whole, modelled from 1920 through to 2100
• Exposure: Asbestos consumed in Australia from 1920 to 2003, 12.8 million tonnes in total, allocated in the model to product groups: cement sheeting (domestic and commercial), cement water pipes, flooring products, friction products, roofing products and other
• Main results:
  • Best estimate for stocks: peak of 10.5 Mt in 1981. By 2011, 50% of consumed asbestos remained in use. In 2016, 44% (5.6 Mt) remained in stock. By 2055, 10% will remain.
  • Across the best, low and high lifetime estimates, the year of peak stocks ranged from 1980 to 1986
  • Best estimate for waste flows: asbestos waste quantities peaked in 2004 at 170 kt and declined thereafter
  • The peak waste year ranged from 1983 under the short lifetime estimate to 2041 under the long lifetime estimate
  • The modelled decline in waste was not consistent with landfill records, which showed uneven annual quantities but an apparent recent upward trend
  • The conclusion section states the best-estimate waste peak as 2014, which differs from the 2004 given in the results section
• The authors' conclusion: The authors concluded that the model provides a first-order estimate of asbestos stocks and flows in Australia, and that it offers a way to project future asbestos waste quantities
• Limitations the authors state:
  • The model cannot differentiate between different types of asbestos
  • The model does not account for the impact of government interventions
  • Sensitivity analysis showed significant variation in the results, reflecting uncertainty in input parameters, particularly product lifespans
  • Very little information was available on how asbestos was allocated to product groups in specific years
  • Pipe lifetime data came from Western Australia, so applying them to the rest of Australia is an assumption
  • No data sources were found to confirm replacement intervals for friction products, so the authors assumed these were retired with the vehicle
  • Mixing of asbestos waste with demolition waste and soil is not part of the primary model
  • Variation in soil and rubble volumes in landfill consignments could mask the trend in asbestos-containing product waste

Topics

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

Related studies

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• The transformation sequence of cement-asbestos slates up to 1200 degrees C and safe recycling of the reaction product in stoneware tile mixtures — A.F. Gualtieri, C. Cavenati, et al. (2008)
• Neutralization of cement-asbestos waste by melting in an arc-resistance furnace — J. Witek, R. Kusiorowski (2017)
• Accuracy of a mobile app to identify suspect asbestos-containing material in Australian residential settings — M.H. Govorko, L. Fritschi, et al. (2018)
• Current and future risks of asbestos exposure in the Australian community — C. Gray, R.N. Carey, et al. (2016)
• Asbestos concerns in Australian buildings — T.K. Burki (2016)

Browse more research in Waste Management & Research, or return to medical research.