Novel selective dyeing method for chrysotile asbestos detection in concrete materials

Our plain-English summary of Novel selective dyeing method for chrysotile asbestos detection in concrete materials, by Y. Oke, N. Yamasaki, G.Y. Amamoto, et al (Environmental Science & Technology, 2008).

The study

• Authors: Y. Oke, N. Yamasaki, G.Y. Amamoto, K. Sasaki, N. Maeta, H. Fujimaki, T. Hashida
• Journal: Environmental Science & Technology
• Published: 2008;42(5):1638-42
• Read it: PubMed · Publisher

Abstract

There are a tremendous number of asbestos-containing buildings without any surveys on the presence of asbestos because of the difficulty to detect asbestos in building materials simply and quickly, although a great deal of worldwide effort was put into removing asbestos of which inhalation causes serious diseases. In this study, we newly developed a simple dyeing method to detect chrysotile asbestos, the most commonly used type of asbestos, in asbestos-cement composite materials using magnesium-chelating organic dyes. As an essential process for selective dyeing of chrysotile asbestos, special pretreatment with a calcium-chelating agent was developed to prevent the dyes from reacting with calcium, which is the major component of concrete materials. Our developed selective dyeing method was shown to possess sufficient sensitivity for detecting chrysotile asbestos in an amount greater than 0.1 mass% in concrete specimens, and there was an approximately linear relationship between the area fraction of dyed spots and the mass fraction of chrysotile asbestos. Our results may provide a basis for further development of a simple on-site detection method for chrysotile asbestos in building materials and may facilitate the progress of control and removal of asbestos in the environment.

In plain English

This was a laboratory study that developed a dyeing method for spotting chrysotile asbestos in cement and concrete. It examined materials, not people, and did not look at health effects. The authors tested an asbestos cement slate, whose fibers they identified as chrysotile using microscopy and elemental analysis. They also tested concrete pieces they made with set amounts of chrysotile, from zero to 15 percent by mass. Specimens were first soaked in a calcium-binding chemical called EGTA and then in a magnesium-binding dye, either Ponceau S or Trypan Blue. With the EGTA pretreatment, the chrysotile fiber bundles in the slate showed up as dyed spots. Without it, the whole surface dyed evenly and the fibers could not be told apart from the cement. Concrete with no asbestos showed no dyed spots, and spots were readily seen at 0.1 percent by mass. The dyed area rose roughly in line with asbestos content, though the measurements scattered considerably. The authors concluded that the method could be a basis for simple, quick on-site detection of chrysotile in building materials.

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: Laboratory method-development experiment (no human subjects)
• Who was studied: Building-material specimens: pieces of an asbestos cement slate, and laboratory-made portland cement concrete specimens containing chrysotile asbestos at mass fractions from zero to 15 mass%
• Exposure: Chrysotile asbestos in cement-based materials. Specimens were pretreated with the calcium-chelating agent EGTA and then dyed with the magnesium-chelating dyes Ponceau S or Trypan Blue. Cement slate specimens without pretreatment were dyed for comparison.
• Main results:
  • In polarized light microscopy of the cement slate, all fiber bundles had extinction angles between 0 and 7 degrees, consistent with chrysotile (80 bundles measured), and no other fiber types were seen
  • In cement slate specimens pretreated with EGTA, dyed spots appeared, and EDX analysis identified them as chrysotile fiber bundles
  • Without EGTA pretreatment, the cement slate surfaces dyed uniformly and cement could not be distinguished from chrysotile
  • In the concrete specimens, the number and area of dyed spots increased as the chrysotile mass fraction increased
  • The concrete specimen with no chrysotile (0 mass%) showed no dyed spots
  • Dyed spots were readily observed in the concrete specimen containing 0.1 mass% chrysotile
  • The area fraction of dyed spots showed an approximately linear relationship with the mass fraction of chrysotile
• The authors' conclusion: The authors concluded that the selective dyeing method with calcium-masking pretreatment may have sufficient sensitivity to detect the regulated quantity of chrysotile in concrete, and is expected to provide a basis for a simple and quick on-site detection method for chrysotile asbestos in building materials.
• Limitations the authors state:
  • The authors noted significant scatter in the measured area fractions of dyed spots

Topics

The National Library of Medicine indexes this study under subjects our site covers: Chrysotile.

Medical terms in this study, explained in our Lexicon: Chrysotile, Asbestos-Cement.

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