Non-neoplastic and neoplastic pleural endpoints following fiber exposure

Our plain-English summary of Non-neoplastic and neoplastic pleural endpoints following fiber exposure, by V.C. Broaddus, J.I. Everitt, B. Black, et al (Journal of Toxicology and Environmental Health. Part B, Critical Reviews, 2011).

The study

• Authors: V.C. Broaddus, J.I. Everitt, B. Black, A.B. Kane
• Journal: Journal of Toxicology and Environmental Health. Part B, Critical Reviews
• Published: 2011;14(1-4):153-78
• Type of article: Review
• Cited by: 42 articles, as counted by NIH iCite
• Read it: PubMed · Publisher · Free full text

Abstract

Exposure to asbestos fibers is associated with non-neoplastic pleural diseases including plaques, fibrosis, and benign effusions, as well as with diffuse malignant pleural mesothelioma. Translocation and retention of fibers are fundamental processes in understanding the interactions between the dose and dimensions of fibers retained at this anatomic site and the subsequent pathological reactions. The initial interaction of fibers with target cells in the pleura has been studied in cellular models in vitro and in experimental studies in vivo. The proposed biological mechanisms responsible for non-neoplastic and neoplastic pleural diseases and the physical and chemical properties of asbestos fibers relevant to these mechanisms are critically reviewed. Understanding mechanisms of asbestos fiber toxicity may help us anticipate the problems from future exposures both to asbestos and to novel fibrous materials such as nanotubes. Gaps in our understanding have been outlined as guides for future research.

In plain English

This article was a review, not a new study. The authors reviewed published research on how asbestos fibers reach and stay in the pleura, the lining of the lungs and chest wall. They also reviewed proposed biological mechanisms behind non-cancer pleural diseases (benign asbestos pleurisy, pleural plaques, diffuse pleural thickening, rounded atelectasis) and diffuse malignant pleural mesothelioma. They drew on human studies, rodent experiments and cell-culture work. The work they summarized included three findings. Boutin and colleagues (1996) reported asbestos fibers concentrated in focal "black spots" of the parietal pleura in eight exposed patients. A follow-up of workers exposed to Libby vermiculite reported pleural changes rising from 2% in 1980 to 29% (80 of 280 workers) in 2005. A meta-analysis found amphibole asbestos more potent than chrysotile for mesothelioma. The authors noted that most pleural fiber burden studies reported short chrysotile fibers, whose role in disease has not been established. They stated that animal data may have limited relevance to humans and that tissue sampling can introduce error. The authors concluded by outlining knowledge gaps, including for newer fibrous materials such as nanotubes, as guides for future research.

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 of published research (human, animal and cell-culture studies) on pleural effects of fibers
• Who was studied: No new population studied; the authors reviewed published studies in humans, laboratory animals (rats, hamsters, mice) and cell cultures
• Exposure: Asbestos fibers (chrysotile, amosite, crocidolite, tremolite), Libby amphibole (winchite, richterite, tremolite) in Libby vermiculite, erionite, synthetic vitreous fibers, and carbon nanotubes
• Main results:
  • The authors summarized Boutin et al. (1996). In 8 asbestos-exposed patients, that study reported fibers accumulated in focal "black spots" of the parietal pleura. The mean concentration was 4.1 (plus or minus 1.9) million fibers per gram in black spots versus 0.5 (plus or minus 0.2) million per gram in normal parietal pleura.
  • The authors summarized a 25-year follow-up of workers exposed to Libby vermiculite (Rohs et al.). The prevalence of pleural changes in these workers rose from 2% in 1980 to 29% (80 of 280 workers) in 2005.
  • The authors cited a meta-analysis of epidemiologic evidence (Berman and Crump, 2008) reporting that amphibole asbestos is more potent than chrysotile asbestos in inducing diffuse malignant mesothelioma.
  • The authors noted that most studies of pleural fiber burden reported short chrysotile fibers, and that the role of these fibers in pleural disease has not been established.
  • The authors described pleural plaques as the most common pleural manifestation of asbestos exposure.
• The authors' conclusion: The authors concluded that understanding mechanisms of asbestos fiber toxicity may help anticipate problems from future exposures to asbestos and to novel fibrous materials such as nanotubes. They outlined gaps in understanding as guides for future research.
• Limitations the authors state:
  • The authors stated that data from animal studies may have limited relevance for humans, because the visceral pleura of rodents differs from that of humans.
  • The authors stated that tissue sampling for fiber burden is a potential source of error, because fibers are unevenly distributed, especially in the parietal pleura.
  • The authors noted that, because of its lower biopersistence, chrysotile may not be reliably analyzed by autopsy studies.

Topics

The National Library of Medicine indexes this study under subjects our site covers: Pleural plaques and thickening.

Medical terms in this study, explained in our Lexicon: Fibrosis, Pleural Mesothelioma, Translocation, Pleura.

Related studies

• Pulmonary endpoints (lung carcinomas and asbestosis) following inhalation exposure to asbestos — B.T. Mossman, M. Lippmann, et al. (2011)
• Factors that impact susceptibility to fiber-induced health effects — J.E. Below, N.J. Cox, et al. (2011)
• Models for mesothelioma incidence following exposure to fibers in terms of timing and duration of exposure and the biopersistence of the fibers — G. Berry (1999)
• p53, Cip1, and Gadd153 expression following treatment of A549 cells with natural and man-made vitreous fibers — N.F. Johnson, R.J. Jaramillo (1997)
• Macrophage phagocytic activity and cell phagocytic capacity following intratracheal instillation of a comixture of asbestos fibers — I. Trosic, M. Matausic-Pisl, et al. (1995)
• Are pleural plaques an appropriate endpoint for risk analyses? — L.D. Maxim, R. Niebo, et al. (2015)

Browse more research in Journal of Toxicology and Environmental Health. Part B, Critical Reviews, or return to medical research.