Occupational exposure to airborne asbestos from coatings, mastics, and adhesives

Our plain-English summary of Occupational exposure to airborne asbestos from coatings, mastics, and adhesives, by D.J. Paustenbach, A. Sage, M. Bono, et al (Journal of Exposure Analysis and Environmental Epidemiology, 2004).

The study

• Authors: D.J. Paustenbach, A. Sage, M. Bono, F. Mowat
• Journal: Journal of Exposure Analysis and Environmental Epidemiology
• Published: 2004;14(3):234-44
• Cited by: 12 articles, as counted by NIH iCite
• Read it: PubMed · Publisher

Abstract

Over the past few years, a question has arisen about the degree of exposure to airborne asbestos associated with the application, cleanup, and tear-out of glues and mastics used between 1940 and the present. These liquid products were used either to adhere insulation to pipes and boilers or to cover the insulation so as to protect it. In this study, four asbestos-containing products, a coating, two mastics, and an adhesive, which were representative of the various classes of products that have been used historically, were tested to determine the airborne concentration of asbestos fibers released during five different activities (application, spill cleanup, sanding, removal, and sweep cleaning). Each activity was performed for 30 min (often in triplicate). Personal (n=172) and area (n=280) air samples were collected during the tests, and each was analyzed for total fiber concentrations using phase contrast microscopy (PCM), and for asbestos fiber count using transmission electron microscopy (TEM). A measurable concentration of asbestos fibers was detected in six of the 452 samples collected (0.0017-0.0184 fibers/ml). The observed asbestos fibers counts for each product were similar to background. Only one asbestos fiber was detected in an indoor background sample; no asbestos fibers were identified in any of the outdoor background samples. The (raw) PCM-total fiber concentrations were adjusted based on TEM analyses that reported fraction of asbestos fibers (to derive a PCM-asbestos concentration) and by the fraction of the 8-h workday that a worker spends performing the activity (to derive a calculated TWA). For the coatings, mastics, and adhesives evaluated in the present study, the calculated TWAs using hypothetical work scenarios were well below the current Occupational Safety and Health Administration (OSHA) Permissible Exposure Limit (PEL) of 0.1 fibers/ml. The calculated TWAs ranged from 0.03 to 0.009 fibers/ml. The actual concentration of airborne asbestos due to these products is almost certainly much less than the TWAs, and may be so low as to not be measurable. These results support the historical view that these products, over the past 50 years, did not pose an occupational health hazard under foreseeable uses.

In plain English

This was an experimental air-sampling study. Four products once made by Amchem Products, Inc. were remanufactured in 2002 from 1960s formulation sheets: a coating (Lagtone 31-95), two mastics (Sealfas 41-96 and C.I. Mastic 60-25) and an adhesive (Fibrous Adhesive 81-27). They contained about 1% to 9% chrysotile asbestos. All four were applied and tested in spill cleanup; three were also sanded, and only Lagtone 31-95 and Sealfas 41-96 were cut away and swept up. Testing was indoors or outdoors, and 172 personal and 280 area air samples were taken. Electron microscopy found asbestos fibers in six of the 452 samples. All were chrysotile, at 0.5 to 1 fiber per sample, and none were found during application or removal. One asbestos fiber was found in an indoor background sample. For hypothetical workdays, the authors calculated 8-hour average exposures of 0.009 to 0.03 fibers/ml, below the OSHA limit of 0.1 fibers/ml. They noted these values are hard to tell apart from background. The authors concluded there was virtually no occupational exposure to asbestos from these products during the activities tested.

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: Experimental simulation study measuring airborne fibers released from asbestos-containing products during controlled work activities
• Who was studied: No people were studied. Four products (one coating, two mastics, one adhesive) historically made by Amchem Products, Inc. were remanufactured in a pilot plant in summer 2002 from 1960s formulations. They were tested at a single facility (indoor room and outdoor area). In total, 452 air samples were analyzed: 172 personal and 280 area.
• Exposure: Chrysotile asbestos in the products: Lagtone 31-95 about 1%, Sealfas 41-96 about 9%, C.I. Mastic 60-25 about 8%, and Fibrous Adhesive 81-27 about 9% (8% in the text). Five activities were tested, often in triplicate. All four products were tested for application and spill cleanup. Sanding was tested on Lagtone 31-95, Sealfas 41-96 and C.I. Mastic 60-25. Removal (cutting) and sweep cleaning were tested only on Lagtone 31-95 and Sealfas 41-96.
• Main results:
  • Asbestos fibers were detected by TEM in 6 of 452 samples: four area samples and two personal samples.
  • Detections came from sanding, spill cleanup and sweep-cleaning tests. Counts were 0.5 to 1 fiber per sample (five fibers in total), all chrysotile. No asbestos fibers were detected in the application or removal tests.
  • Total fibers (asbestos and non-asbestos) were detected by PCM in 120 of 452 samples. Only eight of these detections were in personal samples, all for Lagtone 31-95.
  • PCM-asbestos concentrations calculated for the samples with asbestos ranged from 0.003 to 0.040 fibers/ml.
  • Background samples: one asbestos fiber was detected in an indoor background sample, and none in outdoor background samples.
  • Scenario A was a hypothetical worker doing application, spill cleanup, sweep cleanup and sanding. The calculated 8-hour TWA was no greater than 0.009 fibers/ml.
  • Scenario B was a hypothetical worker doing 2 hours of spill cleanup and 4 hours of sanding. The calculated 8-hour TWA was 0.03 fibers/ml.
  • Scenario C was a hypothetical worker doing removal/cutting and sweep cleaning. The calculated 8-hour TWA was 0.009 fibers/ml in the Results section; the Discussion prints 0.0009.
  • Using the measured concentrations, the authors calculated that sanding Sealfas 41-96 for 8 hours would give a TWA of 0.04 fibers/ml.
• The authors' conclusion: The authors concluded that calculated TWAs were well below the OSHA PEL of 0.1 fibers/ml. In their view, there was virtually no occupational exposure to the asbestos in these products during application, spill cleanup, sanding, cutting and removal, and sweep cleanup.
• Limitations the authors state:
  • The authors stated that the calculated TWA values are difficult to distinguish from background and may not be due to release from the products.
  • The authors stated that sanding was not a typical or routine activity for these products and was included only to represent aggressive handling.

Topics

Medical terms in this study, explained in our Lexicon: Occupational Exposure, phase contrast microscopy (PCM), Transmission Electron Microscopy (TEM), OSHA, Permissible Exposure Limit (PEL), Foreseeability.

Related studies

• Simulation tests to assess occupational exposure to airborne asbestos from asphalt-based roofing products — F. Mowat, R. Weidling, et al. (2007)
• Airborne exposure during asbestos abatement of floor tile, wall plaster, and pipe insulation — J.H. Lange (2005)
• Asbestos abatement of pipe and floor tile/mastic and comparison of critical plastic barrier controls — J.H. Lange (2004)
• Simulation tests to assess occupational exposure to airborne asbestos from artificially weathered asphalt-based roofing products — P. Sheehan, F. Mowat, et al. (2010)
• Occupational exposure to airborne asbestos from phenolic molding material (Bakelite) during sanding, drilling, and related activities — F. Mowat, M. Bono, et al. (2005)
• Airborne exposure concentrations during asbestos abatement of ceiling and wall plaster — J.H. Lange, K.W. Thomulka (2002)

Browse return to medical research.