Human health risks associated with asbestos abatement

Our plain-English summary of Human health risks associated with asbestos abatement, by P.C. Chrostowski, S.A. Foster, E.L. Anderson (Risk Analysis, 1991).

The study

• Authors: P.C. Chrostowski, S.A. Foster, E.L. Anderson
• Journal: Risk Analysis
• Published: 1991;11(3):465-81
• Cited by: 5 articles, as counted by NIH iCite
• Read it: PubMed · Publisher
• In J-M's library: Johns-Manville's company medical library held a copy (J-M no. 004445).

Abstract

Upperbound lifetime excess cancer risks were calculated for activities associated with asbestos abatement using a risk assessment framework developed for EPA's Superfund program. It was found that removals were associated with cancer risks to workers which were often greater than the commonly accepted cancer risk of 1 x 10(-6), although lower than occupational exposure limits associated with risks of 1 x 10(-3). Removals had little effect in reducing risk to school populations. Risks to teachers and students in school buildings containing asbestos were approximately the same as risks associated with exposure to ambient asbestos by the general public and were below the levels typically of concern to regulatory agencies. During abatement, however, there were increased risks to both workers and nearby individuals. Careless, everyday building maintenance generated the greatest risk to workers followed by removals and encapsulation. If asbestos abatement was judged by the risk criteria applied to EPA's Superfund program, the no-action alternative would likely be selected in preference to removal in a majority of cases. These conclusions should only be interpreted within the context of an overall asbestos risk management program, which includes consideration of specific fiber types and sizes, sampling and analytical limitations, physical condition of asbestos-containing material, episodic peak exposures, and the number of people potentially exposed.

In plain English

This article was a risk assessment, not a study of people. The authors took airborne asbestos measurements reported in earlier published studies of removal, encapsulation and maintenance work. Using EPA Superfund methods, they calculated upper-bound lifetime excess risks of mesothelioma and lung cancer combined for workers, teachers and schoolchildren, assuming all asbestos types equally potent. In their summary table, calculated risks during removal ranged from 9E-08 to 1E-02 (9 in 100 million to 1 in 100), depending on whether respirators were worn. For teachers, risks before and after removal both ranged from 2E-06 to 1E-05. The authors reported that removal did little to reduce risk to school populations, whose risks were about the same as outdoor background. They found that careless everyday maintenance gave workers the greatest risk, followed by removal and then encapsulation. Judging by Superfund risk criteria, the authors concluded that removal from public buildings may not be warranted and may create additional risk when considered from the standpoint of chronic exposure. They advised caution, saying other factors such as peak exposures should also be considered.

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: Quantitative risk assessment using airborne asbestos concentrations taken from the published literature, applying EPA Superfund risk assessment methods
• Who was studied: No people were studied directly. Risks were calculated for hypothetical exposure scenarios: workers (exposed for 13% of a lifetime), schoolchildren (2.7%) and teachers (10%). Risks were also calculated for the general public exposed to background levels.
• Exposure: Inhaled airborne asbestos during removal, encapsulation and operation and maintenance activities, and at background levels. Enclosure was described only qualitatively, without separate risk figures. Measurements were converted to phase contrast microscopy equivalents. All asbestos types were assumed equally potent. The authors noted that the unit risk factors came mainly from studies of the amphiboles amosite, crocidolite and anthophyllite, while most asbestos used in the United States is chrysotile.
• Main results:
  • For workers, the calculated upper-bound excess lifetime cancer risk during removal ranged from 9E-08 to 1E-02, depending on whether a respirator was worn. Respirators were assumed to be 99.97% efficient.
  • In the summary table, teacher risks before removal and after removal both ranged from 2E-06 to 1E-05.
  • Removals had little effect in reducing risk to school populations. However, substantial amounts of airborne asbestos were created during abatement, which the authors said may have posed a risk to workers.
  • Average risks for teachers and students in U.S. public buildings were not substantially different from average outdoor background risks. The authors said these levels may be too low to trigger remedial action under the Superfund program.
  • Careless everyday building maintenance produced the greatest risk to workers, followed by removals and then encapsulation.
  • Two encapsulation studies suggested encapsulation may reduce risk more effectively than removal. The authors said the data were too few for a general conclusion.
  • In a U.K. survey the authors reviewed (Burdett et al.), all three sites undergoing abatement showed signs of leakage from plastic containment barriers.
• The authors' conclusion: The authors applied Superfund-style risk criteria. On that basis, they concluded that removal of asbestos from public buildings may not be warranted by the data and may create additional health risks, when considered from the standpoint of chronic exposure. They advised caution in applying this to risk management decisions. They said fiber type and size, sampling limits, episodic peak exposures and the number of people exposed should also be considered.
• Limitations the authors state:
  • Assuming that all asbestos fiber types are equally potent may introduce substantial uncertainty. The authors considered this most probably an overestimate of risk.
  • The interaction between smoking and asbestos in causing lung cancer was not accounted for.
  • The scope was limited to chronic or repeated exposure to typical levels.
  • Risks were not calculated for episodic or peak exposures.
  • Only mesothelioma and lung cancer were considered. Other diseases were not.
  • Some data were collected in the 1970s, before sampling and analysis methods had evolved.
  • Phase contrast microscopy counts all fibers, not only asbestos, which could raise the calculated risk.
  • Where raw data were unavailable, the authors used statistics as reported by secondary sources without checking them.
  • Respirators were assumed to be 99.97% efficient. The authors said real respirators are never as efficient as the filter alone, so actual risks likely fall between the with-respirator and without-respirator values.

Topics

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

Medical terms in this study, explained in our Lexicon: Abatement, Superfund, Occupational Exposure, Encapsulation, Asbestos-Containing Material (ACM).

Related studies

• Personal airborne asbestos exposure levels associated with various types of abatement — J.H. Lange, K.W. Thomulka, et al. (2006)
• The costs of imprecision: perspectives in asbestos abatement — N.A. Esmen (1991)
• Health effects of World Trade Center (WTC) Dust: An unprecedented disaster's inadequate risk management — M. Lippmann, M.D. Cohen, et al. (2015)
• Occurrence, behaviour, and human exposure pathways and health risks of toxic geogenic contaminants in serpentinitic ultramafic geological environments (SUGEs): A medical geology perspective — W. Gwenzi (2020)
• Retrospective Exposure Assessment Methods Used in Occupational Human Health Risk Assessment: A Systematic Review — F. Borghi, L.A. Mazzucchelli, et al. (2020)
• Carcinogenic industrial air pollution and postmenopausal breast cancer risk in the National Institutes of Health AARP Diet and Health Study — J.M. Madrigal, C.N. Pruitt, et al. (2024)

Browse more research in Risk Analysis, or return to medical research.