Microstructures and biological influence of environmental exposure of asbestos

Our plain-English summary of Microstructures and biological influence of environmental exposure of asbestos, by K. Yada, N. Kohyama (Bio-medical Materials and Engineering, 2009).

The study

• Authors: K. Yada, N. Kohyama
• Journal: Bio-medical Materials and Engineering
• Published: 2009;19(2-3):231-9
• Type of article: Review
• Read it: PubMed · Publisher

Abstract

Asbestos minerals are thin fiber type of minerals and honorably said as "the minerals of the miracle" because of their valuable natures even in the strategic field. On the other hand, the relation between asbestos exposure and diseases such as lung cancer and malignant mesothelioma was proved around 1970 by epidemiology and an animal experiment in relation to their microstructures. Here, microstructures of chrysotile asbestos, a mainstream of asbestos substances, are shown. It is also shown that in what kinds of environment people are exposed to asbestos and what kinds of biological or epidemical things happen after asbestos exposure. Many kinds of fibrous materials as the substitutes of asbestos are described in relation to their carcinogenicity.

In plain English

This article was a review by two authors from Japan, not a new study of people. It described asbestos mineral structure, exposure settings, and health questions about asbestos substitutes. The authors wrote that chrysotile makes up about 90% of asbestos in quantity. Citing the first author's earlier electron microscope work, they described chrysotile fibers as hollow tubes. Diameters differed considerably between samples, with most frequent values of 22–27 nm outside and 2–8 nm inside. They stated that asbestos-related diseases take 20–40 years to show symptoms and that Japan legally banned asbestos from October 2004. They wrote that a residual effect would remain for workers handling asbestos building materials and for demolition contractors. They summarized animal experiments by Stanton and colleagues, who found the highest rate of mesothelioma with fibers less than 0.25 micrometres in diameter and 8 micrometres or more long. Pott and colleagues reported the identical result. A table of substitute fibers marked some as having reported carcinogenicity in animal experiments. The authors concluded that the biological effects of new substitutes should be carefully examined before practical use.

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: narrative review
• Who was studied: No study population. The review covered asbestos minerals, including chrysotile samples the first author had earlier examined from many localities such as Globe, AZ and Transvaal, South Africa, and described exposure situations in the USA, Japan and China.
• Exposure: Asbestos minerals: chrysotile (serpentine group) and amphiboles (crocidolite and amosite shown), plus fibrous materials used as asbestos substitutes such as glass fiber, rock wool, ceramic fibers, potassium titanate fiber, silicon carbide and carbon fiber
• Main results:
  • Chrysotile accounts for about 90% of asbestos substances in quantity
  • From the first author's earlier electron microscope work: chrysotile fibers are hollow tubes with concentric and spiral structures. The distribution of diameters differed considerably from sample to sample, depending on growth conditions in each locality.
  • The most frequent outer and inner diameters of chrysotile fibers were 22–27 nm and 2–8 nm
  • Asbestos-related diseases take 20–40 years to show symptoms
  • Japan's asbestos consumption exceeded 300,000 tons per year in the 1970s. Use was legally banned in Japan from October 2004.
  • Despite the ban, the authors wrote that a residual effect of asbestos exposure would remain for workers treating building materials such as asbestos cement, perlite board and slate, for builders of common residences, and for demolition contractors of buildings built with asbestos in large quantities
  • Animal experiments by Stanton et al. (another study, not this one) found that fibers under 0.25 micrometres in diameter and 8 micrometres or more in length showed the highest rate of mesothelioma. Pott et al. reported the identical result.
  • In the authors' table of asbestos substitutes, taken from an earlier source, some substitutes are marked as showing carcinogenicity in animal experiments
• The authors' conclusion: The authors concluded that the biological effects of new asbestos substitutes should be carefully examined before practical use

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: Environmental Exposure, Asbestos, Asbestos Exposure, Lung Cancer, Malignant Mesothelioma, Epidemiology, Chrysotile.

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