Corrigendum. Are airborne refractory ceramic fibers similar to asbestos in their carcinogenicity?

Our plain-English summary of Corrigendum. Are airborne refractory ceramic fibers similar to asbestos in their carcinogenicity?, by A.M. Walker, L.D. Maxim, M.J. Utell (Inhalation Toxicology, 2012).

The study

• Authors: A.M. Walker, L.D. Maxim, M.J. Utell
• Journal: Inhalation Toxicology
• Published: 2012;24(13):928-9
• Cited by: 4 articles, as counted by NIH iCite
• Read it: PubMed · Publisher

Summary of the article

This corrigendum corrected a 2012 analysis (Inhalation Toxicology 24(7):416–424) that had compared lung cancer and mesothelioma mortality in an ongoing mortality study of workers exposed to refractory ceramic fiber (RCF) with the mortality expected if the cohort had been exposed to asbestos at the same fiber concentrations and for the same time. The original paper had concluded that both would have been significantly greater under crocidolite exposure. After publication, an external reviewer found an error in the lung cancer calculations. Cumulative exposure had not been converted from fiber-months to fiber-years per cubic centimeter. In the corrected table, 12 lung cancer deaths were observed. The expected numbers were 11.8 with no fiber effect, 12.2 if RCF were like chrysotile (p = 0.551), and about 16 if like crocidolite, using the potency value RL = 5 from Hodgson and Darnton (2000). The corrected p value for the crocidolite comparison was 0.196, compared with p < 0.001 originally. The authors therefore stated that observed lung cancer mortality could not be distinguished from that expected under crocidolite exposure. An RL of about 9.2 would have been needed to support the original conclusion. For chrysotile, the corrected values did not change the original conclusion. The mesothelioma calculations contained no error. The cohort's zero mesothelioma deaths remained significantly fewer than expected under crocidolite exposure. The next update of the study was scheduled for 2015. The work was funded by the HTIW Coalition, which represents RCF producers.

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

This was a correction notice (corrigendum) from the authors of an earlier 2012 paper in the same journal. That paper used an ongoing mortality study of workers exposed to refractory ceramic fiber (RCF). It compared their lung cancer and mesothelioma deaths with the deaths expected had they been exposed to asbestos at the same fiber levels and for the same time. The authors reported that their lung cancer calculations had not converted cumulative exposure from fiber-months to fiber-years per cubic centimeter. After correction, about 16 lung cancer deaths would be expected if the exposure had acted like crocidolite asbestos. That compared with 12 observed and 11.8 expected with no fiber effect. The corrected p value was 0.196, against less than 0.001 originally. The authors concluded that observed lung cancer mortality could not be distinguished from what crocidolite-like exposure would predict. The mesothelioma calculations had no error: the cohort had zero mesothelioma deaths, which the authors said was significantly fewer than crocidolite exposure would predict. They noted that higher asbestos potency estimates would raise expected lung cancer deaths, and that the study is continuing.

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: Corrigendum (correction notice) to the authors' own earlier analysis, published in Inhalation Toxicology 2012; 24(7): 416–424
• Who was studied: Workers occupationally exposed to refractory ceramic fiber (RCF) in an ongoing mortality study. This notice does not give the cohort size, location or dates. It reports 12 observed lung cancer deaths and zero mesothelioma deaths.
• Exposure: Refractory ceramic fiber (RCF), grouped by cumulative exposure (0–15, over 15–45, over 45–135, and over 135 fiber-months per cubic centimeter). Observed deaths were compared with deaths anticipated if the same exposure had acted like chrysotile (R = 0.5) or like crocidolite/amphibole asbestos (R = 5, the Hodgson and Darnton 2000 estimate for crocidolite).
• Main results:
  • The original lung cancer error came from not converting cumulative exposure from fiber-months per cubic centimeter to fiber-years per cubic centimeter.
  • Under the corrected calculation, about 16 lung cancer deaths (15.955 in the revised table) would be expected if the RCF cohort had been exposed to crocidolite asbestos, using RL = 5. The cohort had 12 observed deaths.
  • The number expected with no fiber effect was 11.8 lung cancer deaths.
  • For the crocidolite comparison, the corrected p value was 0.196, compared with p less than 0.001 in the original paper.
  • The authors calculated that the crocidolite lung cancer potency value (RL) would need to be about 9.2 for their original lung cancer conclusion to hold.
  • Under the chrysotile-like scenario (R = 0.5), the revised table shows 12.216 anticipated lung cancer deaths (p value 0.551). The authors said the corrected chrysotile values differed from the original paper but did not change their original conclusion.
  • The mesothelioma calculations contained no error. The authors stated that mesothelioma deaths in the RCF cohort (zero) would have been significantly greater had the cohort been exposed to crocidolite asbestos.
• The authors' conclusion: The authors concluded that the RCF cohort's observed lung cancer mortality could not be distinguished from what crocidolite-like exposure at the same concentrations and duration would predict. They said their conclusion that the cohort had less mesothelioma mortality than crocidolite exposure would predict remained valid on the available data.
• Limitations the authors state:
  • The lung cancer comparison depends on the assumed potency value for crocidolite. If that value were higher, as some later analyses suggest, the expected deaths would increase and the p value would decrease.
  • The mortality study is ongoing. The authors expect its statistical power to increase as the cohort ages and accumulates exposure, with an update scheduled for 2015.

Topics

Medical terms in this study, explained in our Lexicon: Lung Cancer, Mesothelioma, Crocidolite, Cumulative Exposure, Fiber Year, Chrysotile.

Related studies

• Are airborne refractory ceramic fibers similar to asbestos in their carcinogenicity? — A.M. Walker, L.D. Maxim, et al. (2012)
• Perspectives on refractory ceramic fiber (RCF) carcinogenicity: comparisons with other fibers — H. Greim, M.J. Utell, et al. (2014)
• Potential significance of airborne fiber dimensions measured in the U.S. refractory ceramic fiber manufacturing industry — T.J. Lentz, C.H. Rice, et al. (1999)
• Refractory ceramic fiber (RCF) toxicity and epidemiology: a review — M.J. Utell, L.D. Maxim (2010)
• Risk analysis for mortality from respiratory tumors in a cohort of refractory ceramic fiber workers — A.M. Walker, L.D. Maxim, et al. (2002)
• Review of refractory ceramic fiber (RCF) toxicity, epidemiology and occupational exposure — L.D. Maxim, M.J. Utell (2018)

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