Asbestos in the air of public buildings: a public health risk?

Our plain-English summary of Asbestos in the air of public buildings: a public health risk?, by J. Whysner, V.T. Covello, M. Kuschner, et al (Preventive Medicine, 1994).

The study

• Authors: J. Whysner, V.T. Covello, M. Kuschner, A.B. Rifkind, K.K. Rozman, D. Trichopoulos, G.M. Williams
• Journal: Preventive Medicine
• Published: 1994;23(1):119-25
• Type of article: Review
• Cited by: 12 articles, as counted by NIH iCite
• Read it: PubMed · Publisher

Abstract

The Environmental Health and Safety Council of the American Health Foundation has examined current estimates of cancer risks associated with the presence of asbestos-containing materials (ACM) in public buildings. The Council finds that even complete removal of asbestos from all of these buildings will provide no measurable benefit to public health. The removal of nonfriable ACM only can be postulated to protect the public against a small hypothetical risk that cannot be measured epidemiologically. Moreover, examination of the assumptions used in the risk assessment calculations leads to the conclusion that these small calculated risks are likely to represent overestimates. In recent surveys, the measured asbestos levels in indoor air cast some doubt on whether occupant exposure to asbestos levels are contributed to significantly by ACM even when some of the material is friable or in bad condition. Furthermore, the models used for cancer risk estimates assume no threshold level for cancer and conclude that any exposure is carcinogenic. This may be unjustified in light of information on the mechanisms for some asbestos-caused disease. Based on the best available data, it is very unlikely that cancer will result from indoor asbestos exposure, especially where ACM is well maintained.

In plain English

This review examined estimates of cancer risk from asbestos in the air of U.S. public buildings, including schools. The authors described models that extend lung cancer and mesothelioma risks seen in asbestos workers to the far lower levels found in buildings. Using a study by Crump and Farrar, described as having the most extensive data, they calculated 1.6 cases of the two cancers combined per million people over a lifetime, for 50 years of exposure to an average level of 0.0008 (the unit is not legible). Assuming 70 million people were exposed, that came to about 1.6 cases a year. For schools, one estimate gave 10 to 59 added cases a year in the U.S. population, and another gave an excess of 11 cases. Based on that last calculation, the authors put the contribution at under 0.01% of the roughly 154,000 lung cancer and mesothelioma cases a year nationally. They listed reasons the models may overestimate risk, including possible threshold doses and the use of amphibole-based mesothelioma data for chrysotile. The authors concluded that real risks are most likely lower than predicted and may conceivably be zero, while noting that the methods are replete with uncertainty.

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: review and assessment of published cancer risk estimates and risk models for asbestos in public buildings
• Who was studied: people exposed to asbestos in public buildings, including schools, in the United States, as modeled in risk calculations; no group of people was studied directly
• Exposure: asbestos in the indoor air of public buildings and schools, coming from asbestos-containing material; chrysotile and amphibole fibers are discussed
• Main results:
  • Using the study by Crump and Farrar, described as having the most extensive data, 50 years of exposure to an average level of 0.0008 (unit not shown in the legible passage) was calculated to give 1.6 cases of lung cancer and mesothelioma combined per million lifetime
  • Assuming 70 million people in the United States are exposed at this level, the same risk was expressed as about 1.6 cases per year
  • For school exposure, one set of calculations gave a lifetime incremental risk of 3.5 to 7.0 per million persons, implying an additional 10 to 59 cases per year of lung cancer and mesothelioma combined in the total U.S. population
  • Using the methods of the HEI-AR report and the average school building levels found by Corn et al., an excess of 11 cases of mesothelioma and lung cancer combined was estimated; the legible text does not show the time period or population this figure refers to
  • Compared with about 154,000 lung cancer and mesothelioma cases a year in the United States, exposure from schools and public buildings, based on the calculation immediately preceding it (the 11 excess cases), was estimated to contribute less than 0.01% of the total
  • The authors stated that the added risks from asbestos levels in public buildings are so low that they could not be detected in human studies, even for a rare tumor such as mesothelioma
  • Reasons listed for possible overestimation included possible threshold doses for mesothelioma and lung cancer, and the use of amphibole-related mesothelioma data to estimate risk from chrysotile
  • Among the reasons given for leaving well-maintained asbestos in place: removal may raise air levels for a period of time, and alternatives such as encapsulation are effective
• The authors' conclusion: The authors concluded that real risks are most likely lower than the risks predicted by the models and may conceivably be zero
• Limitations the authors state:
  • The authors stated that the risk-assessment methods used by government agencies are replete with uncertainty

Topics

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

Related studies

• Comments on the Health Effects Institute-Asbestos Research (HEI-AR) report: "Asbestos in public and commercial buildings," with emphasis on risk assessment methods used — T.D. Sterling, C.W. Collett, et al. (1993)
• Adverse health effects of fluoro-edenitic fibers: epidemiological evidence and public health priorities — C. Bruno, P. Comba, et al. (2006)
• Asbestos in New York City public school buildings--public policy: is there a scientific basis? — R. Wilson, A.M. Langer, et al. (1994)
• Asbestos exposures in public and commercial buildings — A.C. Upton, R.A. Shaikh (1995)
• Public Health and Independent Risk Assessment — P. Vineis (2019)
• Rural public health policy models to address an evolving environmental asbestos disaster — S.W. Kuntz, C.A. Winters, et al. (2009)

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