Comment on "Exposure-response modeling of non-cancer effects in humans exposed to Libby Amphibole Asbestos; update" by Benson et al. (2015)

Our plain-English summary of Comment on "Exposure-response modeling of non-cancer effects in humans exposed to Libby Amphibole Asbestos; update" by Benson et al. (2015), by J.E. Goodman, K. Zu, G. Tao, et al (Regulatory Toxicology and Pharmacology, 2016).

The study

• Authors: J.E. Goodman, K. Zu, G. Tao, L.E. Kerper
• Journal: Regulatory Toxicology and Pharmacology
• Published: 2016;80:268-9
• Type of article: Letter, Comment
• Read it: PubMed · Publisher

In plain English

This is a letter to the editor, not a new study. The authors work for the consulting firm Gradient, and their work was funded by W.R. Grace & Co. They commented on an analysis by Benson et al. (2015). That analysis modeled exposure to Libby Amphibole Asbestos (LAA) against chest X-ray and CT changes in a cohort of workers from Marysville, Ohio. The authors argued that localized pleural thickening (LPT) is generally considered a benign marker of exposure, not an adverse health effect or a precursor to asbestosis or cancer. The US EPA used LPT as the basis for its Reference Concentration (RfC) for LAA. The authors stated that two studies Benson et al. cited found lung function in people with LPT was not statistically different from controls. They also raised several method concerns. Detection of changes spanned 30 years. Sensitivity analyses were insufficient. Smoking and body mass index were dropped as covariates. Including time since first exposure was not well justified. The authors considered diffuse pleural thickening and small interstitial opacities appropriate endpoints. They concluded that the Benson et al. results have several limitations and do not support the recent RfC for LAA.

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 (commentary on another published analysis); no original data
• Who was studied: No population was studied by the authors; the letter critiques Benson et al.'s (2015) analysis of a cohort of workers from Marysville, Ohio
• Exposure: Libby Amphibole Asbestos (LAA), as modeled by Benson et al. (2015) and US EPA
• Main results:
  • The authors argued that localized pleural thickening (LPT) is generally considered a benign marker of asbestos exposure, not an adverse health effect
  • The authors stated that two studies cited by Benson et al. (Clark et al. 2014 and Weill et al. 2011) found lung function in the LPT group was not statistically different from controls
  • The authors stated that LPT is not a precursor to asbestosis, cancer, or other asbestos-related diseases
  • The authors argued that combining chest X-ray data from the original cohort with HRCT data from survivors made detection of radiographic changes span 30 years
  • The authors argued that Benson et al. did not perform sufficient sensitivity analyses
  • The authors criticized the exclusion of potential confounders, including smoking and body mass index, because they were not statistically significant
  • The authors argued that time since last occupational exposure would be a more appropriate covariate than time since first exposure
  • The authors considered diffuse pleural thickening (DPT) and small interstitial opacities (SIO) appropriate endpoints for an RfC, while saying those analyses had similar limitations
  • The letter discloses that the authors are employed by Gradient and the work was funded by W.R. Grace & Co.
• The authors' conclusion: The authors concluded that the Benson et al. (2015) results are affected by several limitations and do not support the recent RfC for LAA

Topics

Medical terms in this study, explained in our Lexicon: Libby amphiboles.

Related studies

• Response to comment on "Exposure-response modeling of non-cancer effects in humans exposed to Libby Amphibole Asbestos; update" by Benson et al. (2015) submitted by Goodman et al. (2016) — R. Benson, D. Berry, et al. (2016)
• Comment on "HRCT/CT and Associated Spirometric Effects of Low Libby Amphibole Asbestos Exposure" by Lockey et al (2015) — G. Tao, K. Zu, et al. (2015)
• Influence of exposure assessment and parameterization on exposure response. Aspects of epidemiologic cohort analysis using the Libby Amphibole asbestos worker cohort — T.F. Bateson, L. Kopylev (2015)
• Pulmonary inflammatory and fibrotic responses in Fischer 344 rats after intratracheal instillation exposure to Libby amphibole — D.J. Padilla-Carlin, M.C. Schladweiler, et al. (2011)
• Long-term response of rats to single intratracheal exposure of Libby amphibole or amosite — J.M. Cyphert, D.J. Padilla-Carlin, et al. (2012)
• HRCT/CT and associated spirometric effects of low Libby amphibole asbestos exposure — J.E. Lockey, K. Dunning, et al. (2015)

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