Continued controversy on chrysotile biopersistence

Our plain-English summary of Continued controversy on chrysotile biopersistence, by K. Donaldson, G. Oberdörster (International Journal of Occupational and Environmental Health, 2011).

The study

• Authors: K. Donaldson, G. Oberdörster
• Journal: International Journal of Occupational and Environmental Health
• Published: 2011;17(1):98-9; discussion 99-102
• Type of article: Comment, Letter
• Cited by: 5 articles, as counted by NIH iCite
• Read it: PubMed · Publisher

Summary of the article

In this letter, Donaldson and Oberdörster responded to Henri Pezerat's 2009 article "Chrysotile biopersistence: The misuse of biased studies," which had questioned Dr. Bernstein's inhalation studies reporting short lung half-times for chrysotile. The authors stated that fiber pathogenicity follows a single paradigm in which long, thin, biopersistent fibers are central. They argued that the chrysotile in both the Bernstein studies and the contrasting Coin study had been pre-treated, and that pre-treatment is common and necessary to produce a respirable cloud. They added that chrysotile from different deposits differs in composition, for example in Al content varying by a factor of 5. They noted that Bernstein had reported half-lives from 1/3 day to 11.4 days in different samples. They called for a side-by-side comparison of the samples rather than suspicion of personal bias. In a reply, the journal's editor, David Egilman, noted that Pezerat had died. He argued that "short" fibers and "biopersistence" were not consistently defined, and that short chrysotile fibers predominate in the human pleura. He stated that Bernstein reported clearance half-times of 11.4 days for fibers longer than 20 µm but 108.4 days for fibers shorter than 5 µm. He argued that the three studies the letter cited did not support the biopersistence theory and that sample preparation alters fiber toxicity. He proposed defining short fibers as those under 5 µm. He stated that Donaldson consulted for DuPont on Kevlar.

PubMed has no abstract for this study, and the article doesn't print one. We wrote this summary from the full article with the help of AI. It is not the authors' wording.

In plain English

Donaldson and Oberdörster wrote this letter to the editor, answered by editor-in-chief David S. Egilman; neither presented new data. The letter responded to Henri Pezerat's critique of Bernstein's chrysotile inhalation experiments. The writers argued three things: that biopersistence and fiber length are central to fiber pathogenicity, that fiber pre-treatment is necessary, and that chrysotile from different deposits may persist differently. They cited Bernstein's half-lives of 1/3 day to 11.4 days and called for side-by-side comparison of Bernstein's and Coin's samples. The editor questioned how "short" and "biopersistence" were defined. The editor also argued that fibers clearly persist long enough to cause disease, citing mutagenic effects within hours, days and weeks. The reply called the writers' range misleading because it covered fibers longer than 20 µm. Bernstein reported 29.7 days for fibers 5 to 20 µm and 108.4 days for fibers under 5 µm. The reply said Bernstein did not describe sample preparation, noted Donaldson consults for DuPont on Kevlar, and judged Pezerat's critique "on target." The writers denied alliance with, or funding from, asbestos manufacturers or pro-asbestos pressure groups. The editor disclosed litigation consulting for injured workers and companies.

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: Letter to the editor (correspondence) with a reply from the journal's editor-in-chief; no original data
• Exposure: Chrysotile asbestos, specifically how long its fibers persist in the lung (biopersistence) in published inhalation experiments, and whether fiber pre-treatment affected those results
• Main results:
  • Argument (letter writers, not a finding): a fiber pathogenicity paradigm places biopersistence and fiber length at its centre
  • Argument (letter writers): pre-treatment of fibers is common and necessary to produce a respirable cloud
  • Argument (letter writers): the chrysotile used by Coin may have been more resistant to dissolution and breakage than Bernstein's samples
  • Letter writers cited half-lives from Bernstein's work (another study) of 1/3 day to 11.4 days in different chrysotile samples
  • Letter writers stated that both the Bernstein and the Coin studies could be criticized for poorly describing pre-treatment
  • Editor's reply argued that biopersistence, like "short", was not defined
  • Editor's reply argued that the key question is whether fibers persist long enough to induce disease, and answered that they clearly do
  • Editor's reply cited studies (other studies) showing mutagenic effects associated with carcinogenicity within hours, days and weeks
  • Editor's reply called the letter writers' 1/3 to 11.4 day range misleading and incomplete because it applied to fibers longer than 20 µm
  • Editor's reply cited Bernstein et al.'s clearance half-times (another study): 11.4 days for fibers longer than 20 µm, 29.7 days for fibers 5 to 20 µm, and 108.4 days for fibers shorter than 5 µm
  • Editor's reply argued that short chrysotile fibers are the predominant, often the only, fiber found in the human pleura
  • Editor's reply stated that Bernstein did not describe the source and preparation of the fibers used
  • Editor's reply stated that Donaldson consults for DuPont on Kevlar
  • Editor's reply concluded that Pezerat's critique of the biopersistence theory was on target
  • Letter writers stated they were not allied to, or funded by, any asbestos manufacturing company or pro-asbestos pressure group
  • Editor's disclosure: consulting for injured workers and companies in asbestos litigation
• The authors' conclusion: The letter writers concluded that hard data, not suspicion of bias, were needed to explain variability in chrysotile retention half-time. They called for side-by-side comparison of the chrysotile samples used by Coin and by Bernstein.

Topics

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

Medical terms in this study, explained in our Lexicon: Chrysotile, biopersistence, Pleura.

Related studies

• Chrysotile biopersistence: the misuse of biased studies — H. Pezerat (2009)
• Chrysotile biopersistence in the lungs of persons in the general population and exposed workers — A.M. Langer, R.P. Nolan (1994)
• A biopersistence study following exposure to chrysotile asbestos alone or in combination with fine particles — D.M. Bernstein, K. Donaldson, et al. (2008)
• Comparison of Calidria chrysotile asbestos to pure tremolite: final results of the inhalation biopersistence and histopathology examination following short-term exposure — D.M. Bernstein, J. Chevalier, et al. (2005)
• The importance of fiber biopersistence and lung dose in determining the chronic inhalation effects of X607, RCF1, and chrysotile asbestos in rats — T.W. Hesterberg, G.A. Hart, et al. (1998)
• The biopersistence of Canadian chrysotile asbestos following inhalation: final results through 1 year after cessation of exposure — D. Bernstein, R. Rogers, et al. (2005)

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