Biodurability/retention of Libby amphiboles in a case of mesothelioma

Our plain-English summary of Biodurability/retention of Libby amphiboles in a case of mesothelioma, by R.F. Dodson, E.J. Mark, L.W. Poye (Ultrastructural Pathology, 2014).

The study

• Authors: R.F. Dodson, E.J. Mark, L.W. Poye
• Journal: Ultrastructural Pathology
• Published: 2014;38(1):45-51
• Type of article: Case report
• Cited by: 4 articles, as counted by NIH iCite
• Read it: PubMed · Publisher

Abstract

Mesothelioma is considered a signal tumor for exposure to asbestos (fibrous materials) and can occur decades after first exposure. The present case study reports on tissue burden of fibrous dust in a person who used a vermiculite material (Zonolite) as an attic insulator some 50 years prior to her death. The exposure occurred in two construction/renovation projects in her private residencies. She potentially had exposures to wall board/joint compounds during renovations. She additionally was reported to occasionally be involved in occupational activity, including drilling holes in presumed asbestos-containing electrical boxes. The tissue burden analysis revealed the presence of noncommercial amphibole asbestos fibers and consistent presence in the lung and lymph samples of Libby amphibole fibers. The findings of Libby amphibole fibers in human tissue can be attributed to exposure to Libby vermiculite. This study illustrates that analytical transmission electron microscopy can distinguish these structures from "asbestos" fibers. Further, the findings indicate that a population of these structures is biodurable and retained in the tissue years after first/last exposure.

In plain English

This case report described one person, an 81-year-old woman diagnosed with diffuse malignant mesothelioma after imaging showed a pleural-based mass in the right chest. She died about 3 months after diagnosis. In 1964 to 1965 and in the early 1970s she poured and spread bags of Zonolite vermiculite insulation in the attics of two homes, and during those renovations she sanded wallboard and joint compound. From the mid 1950s until the 1970s she also worked with her husband in their electrical and refrigeration business, where they sometimes drilled holes in electrical boxes. The authors analyzed her lung and lymph node tissue by microscopy. Libby amphibole fibers were found at all sites examined. In the right lung they were equivalent to 96,410.7 per gram dry weight, and in the lymph tissue to 508,810.8 fibers per gram dry weight. A few tremolite asbestos, anthophyllite asbestos and talc fibers were also found. Most Libby amphibole fibers were long: 94.4% were longer than 5 micrometers, and their average length was 20.7 micrometers. The authors concluded that Libby amphiboles are biodurable and can remain in lung and lymph tissue long after sporadic exposure.

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: Case report: analysis of fiber content (tissue burden) in lung and lymph node tissue from one person with mesothelioma
• Who was studied: One 81-year-old woman with hypertension. She presented with symptoms in November 2011, had a pleural-based mass in the right chest, was diagnosed with diffuse malignant mesothelioma, and died about 3 months after diagnosis. Twelve pieces of lung tissue (left and right lung) and three pieces of peribronchial lymph tissue were analyzed. No location is given for the patient.
• Exposure: Pouring and spreading bags of Zonolite (vermiculite) attic insulation in two homes, in 1964 to 1965 and in the early 1970s. Sanding of wallboard and joint compound during the same renovations. Electrical work in the family electrical and refrigeration business from the mid 1950s until the 1970s, including drilling holes in electrical boxes. The authors put the time from the Zonolite exposure to death at more than 50 years.
• Main results:
  • Libby amphibole fibers were found at every site examined, at both high and low magnification. The lymph samples had the highest percentage of total fibers being Libby amphiboles.
  • Right lung, high-magnification scan: 3 Libby amphiboles, equivalent to 96,410.7 per gram dry weight of tissue. The same scan also found 2 tremolite asbestos fibers and 1 talc fiber/ribbon.
  • Lymph tissue, high-magnification scan: 6 Libby amphiboles, equivalent to 508,810.8 fibers per gram dry weight of tissue. The same scan also found 1 tremolite asbestos fiber, 1 anthophyllite asbestos fiber, 1 silica fiber, 1 titanium fiber and 5 talc fibers/ribbons.
  • Left lung, high-magnification scan: 2 talc fibers/ribbons, 1 anthophyllite asbestos fiber, 1 tremolite cleavage fragment and 1 Libby amphibole.
  • One classical ferruginous body was found in the left lung sample, equivalent to 20 per gram wet weight, which was the detection limit. None was detected in the lymph tissue.
  • 94.4% of the Libby amphibole structures were longer than 5 micrometers, and their average length was 20.7 micrometers. The scanned text prints the unit as 'mm', a scanning error for the micrometer symbol: fibers counted by electron microscopy within grid openings cannot be centimeters long.
  • No ferruginous bodies or uncoated fibers were found in the control blanks.
• The authors' conclusion: The authors concluded that Libby amphiboles are biodurable. In their view, sporadic exposure over months, here from dumping bags of vermiculite in attics, can result in a population of Libby amphiboles remaining long-term in lung and lymph tissue.
• Limitations the authors state:
  • The tissue burden shows only what was in the tissue at the time of sampling.
  • Because of clearance over more than 50 years, the authors assumed the Libby amphibole found reflects only a small fraction of what was originally in the lung.

Mines named here

Asbestos mines this study is about. Each mine's page says who ran it, when it worked, and what it produced.

• Libby vermiculite mine, Montana

All asbestos mines

Topics

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

Medical terms in this study, explained in our Lexicon: Libby amphiboles, Mesothelioma, Signal Tumor, vermiculite, Zonolite, Insulator, Joint Compound, Amphibole Asbestos.

Related studies

• In vitro determinants of asbestos fiber toxicity: effect on the relative toxicity of Libby amphibole in primary human airway epithelial cells — K.E. Duncan, P.M. Cook, et al. (2014)
• Separation and characterization of respirable amphibole fibers from Libby, Montana — J.S. Webber, D.J. Blake, et al. (2008)
• Lung cancer screening in patients with Libby amphibole disease: High yield despite predominantly environmental and household exposure — G. Loewen, B. Black, et al. (2019)
• Mortality in a cohort of vermiculite miners exposed to fibrous amphibole in Libby, Montana — J.C. McDonald, J. Harris, et al. (2004)
• Internalization of Libby amphibole asbestos and induction of oxidative stress in murine macrophages — D.J. Blake, C.M. Bolin, et al. (2007)
• Associations between radiographic findings and spirometry in a community exposed to Libby amphibole — T.C. Larson, M. Lewin, et al. (2012)

Browse more research in Ultrastructural Pathology, or return to medical research.