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This document provides information about fiberglass fragments and indoor air quality fiberglass contamination issues in residential and light-commercial buildings. © Copyright 2010 Daniel Friedman, All Rights Reserved. Information Accuracy & Bias Pledge is at below-left. Use links at the left of each page to navigate this document or to view other topics at this website. Green links show where you are in our document or website.

Airborne Fiberglass Fragments as a Possible Health Concern

A Guide to Large versus Very Small Fiberglass Fragments in Building Dust

In our page top photo of fiberglass insulation fragments collected in an indoor air sample, you can see not only a large and typical fiberglass insulation strand with its characteristic colored resin binder. You can also spot much smaller fiberglass fragments.

When a forensic laboratory is asked to screen dust or air samples for fiberglass, depending on the lab's protocols it's not certain that fibers of both large dimension and small fiber fragments will both be reported.

Small glass fiber fragments are easily "lost" in other non-fungal granular debris in building dust. We posit that studies of the level of airborne fiberglass in buildings may be faulty if the methods used to screen for fiberglass fragments do not include small, even sub-micron particles along with the common large particles.

Most Buildings Probably have Mostly Large Fiberglass Fragments - Some Have Sub-Micron Fragments of Fiberglass Dust

Our field and lab experience suggest that while we find fiberglass in nearly all modern indoor environmental dust, the common particles are usually long and large (and presumed less of a health risk than very small particles).

However in environments where fiberglass insulation is old, damaged by foot traffic, handling, pests such as mice, or where it was chopped or disturbed, on occasion we find high levels of very small, even sub-micron fiberglass particles.

We may also find an elevated level of small fiberglass insulation fragments in buildings or in the HVAC system of buildings where fiberglass-lined HVAC ductwork has been mechanically cleaned - a process that can loosen and damage the fiberglass liner. We have also found high levels of fiberglass fragments in indoor air and dust in buildings where amateur do-it-yourself return air ducts were constructed using conventional fiberglass insulating batts as a "duct" liner (photo, above-left).

Therefore a first level of inspection for this hazard starts with the age of the building and the visual determination of the condition of its insulation.

Fiberglass fragments are inorganic material typically from fiberglass insulation; depending on their size and quantity these may be a respiratory irritant or may contribute to more serious health concerns.

The presence of incidental fibers in buildings is common. The Association of Man-made Mineral Fiber Producers asserted to the US EPA in 1992 that a study at that time " does not provide evidence of significant adverse health effects following inhalation of glass fiber." ("Respirable Fibrous Glass Chronic Multidose Inhalation Study-Preliminary Final Results," TIMA, 4 May 1992 delivered to U.S. EPA by hand.) The Seventh Annual Report on Carcinogens (June 1994) lists glass fibers of respirable size as a substance "reasonably anticipated to cause cancer in humans."

DJF Opinion: Caution about fiberglass fragment size: when reading studies about airborne fiberglass, pay close attention to the methods used to collect samples and the methods used to identify and count fiberglass particle fragments. For example, some counting devices or microscopic methods exclude all particles below a give size by the choice of instrument or counting method itself. See Lab Identification of Fiberglass for details.

Deciding not to look for very small particles (which if present may be the more harmful ones) or using a methodology that excludes them means that study is not going to find them even if they in fact were dominant by number or even total volume in a sample.

Prudent Avoidance of Fiberglass Insulation Dust

It is possible that small fiberglass particles in air may constitute a meaningful health risk (obviously depending on the overall exposure level) which has not been explored. It seems reasonable to me to suggest that that prudent avoidance of fiberglass dust would be appropriate. Improper cleaning or treatment of fiberglass ducts with biocides and particularly, mechanical cleaning that can damage the fiberglass lining HVAC ducts may in fact increase rather than decrease indoor air quality problems in a building, particularly if occupants have other respiratory or pulmonary concerns/vulnerabilities.

See Glass Wool Fibers Expert Panel Report, Part B - Recommendation for Listing Status for Glass Wool Fibers and Scientific Justification for the Recommendation" for a 2009 update on the carcinogenicity of fiberglass fragments.

Following a discussion of the body of knowledge, the expert panel reviewed the RoC listing criteria and made its recommendation. The expert panel recommended by a vote of 8 yes/0 no that glass wool fibers, with the exception of special fibers of concern (characterized physically below), should not be classified either as known to be a human carcinogen or reasonably anticipated to be a human carcinogen. The expert panel also recommended by a vote of 7 yes/0 no/1 abstention, based on sufficient evidence of carcinogenicity in well-conducted animal inhalation studies, that special-purpose glass fibers with the physical characteristics as follows longer, thinner, less soluble fibers (for 1 example, > 15 μm length with a kdis of < 100 ng/cm2/h) are reasonably anticipated to be a human carcinogen for the listing status in the RoC. The major considerations discussed that led the panel to its recommendation include the observations of tumors in multiple species of animals (rats and hamsters). Both inhalation and intraperitoneal routes of exposure produced tumors, although inhalation was considered more relevant for humans.

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FIBERGLASS HAZARDS
  FIBERGLASS CONTAMINATION TEST PROCEDURE
  Recognizing Fiberglass Insulation
  Recognizing Fiberglass Duct Insulation
  Lab Identification of Fiberglass
  Fiberglass Fragment Hazards
  Fiberglass Detection in Building Air
  Mold in Fiberglass Insulation
  Mold in Foam Insulation
  Moldy insulation may look clean
  Why does mold grow in fiberglass?
  When to test insulation for mold
  How to Test for Mold in Insulation
  Fiberglass Hazard References

INSULATION INSPECTION & IMPROVEMENT

For more information about fiberglass as an indoor air quality concern see:

• Fiberglass in Indoor Air, HVAC Ducts, and Building Insulation
• Fiberglass Particle Identification in the Fiberglass Test Laboratory
• Goodman Gray Flex Duct Deterioration and Failures
• Mold in Fiberglass Insulation
• Optimum Indoor Air Filters
• Owens Corning Flex Duct Deterioration and Failures
• World Trade Center Dust Particle Identification

• Fiberglass building insulation and HVAC duct work insulation hazards
• Fiberglass carcinogenicity: "Glass Wool Fibers Expert Panel Report, Part B - Recommendation for Listing Status for Glass Wool Fibers and Scientific Justification for the Recommendation", The Report on Carcinogens (RoC) expert panel for glass wool fibers exposures met at the Sheraton Chapel Hill Hotel, Chapel Hill, North Carolina on June 9-10, 2009, to peer review the draft background document on glass wool fibers exposures and make a recommendation for listing status in the 12th Edition of the RoC. The National Institute of Environmental Health Sciences is one of the National Institutes of Health within the U.S. Department of Health and Human Services. The National Toxicology Program is headquartered on the NIEHS campus in Research Triangle Park, NC. The National Institute of Environmental Health Sciences is one of the National Institutes of Health within the U.S. Department of Health and Human Services. The National Toxicology Program is headquartered on the NIEHS campus in Research Triangle Park, NC.

  Following a discussion of the body of knowledge, the expert panel reviewed the RoC listing criteria and made its recommendation. The expert panel recommended by a vote of 8 yes/0 no that glass wool fibers, with the exception of special fibers of concern (characterized physically below), should not be classified either as known to be a human carcinogen or reasonably anticipated to be a human carcinogen. The expert panel also recommended by a vote of 7 yes/0 no/1 abstention, based on sufficient evidence of carcinogenicity in well-conducted animal inhalation studies, that special-purpose glass fibers with the physical characteristics as follows longer, thinner, less soluble fibers (for 1 example, > 15 μm length with a kdis of < 100 ng/cm2/h) are reasonably anticipated to be a human carcinogen for the listing status in the RoC. The major considerations discussed that led the panel to its recommendation include the observations of tumors in multiple species of animals (rats and hamsters). Both inhalation and intraperitoneal routes of exposure produced tumors, although inhalation was considered more relevant for humans.

• Fiberglass insulation mold: occurrence of mold contamination in fiberglass insulation can be impossible to see with the naked eye, but can be significant

• World Health Organization International Agency for Research on Cancer - IARC Monographs on the Evaluation of Carcinogenic Risks to Humans - VOL 81 Man-Made Vitreous Fibers, 2002, IARCPress, Lyon France, pi-ii-cover-isbn.qxd 06/12/02 14:15 Page i - World Health Organization, 1/21/1998. - Fiberglass insulation is an example of what IARC refers to as man made vitreous fiber - inorganic fibers made primarily from glass, rock, minerals, slag, and processed inorganic oxides. This article provides enormous detail about fiberglass and other vitreous fibers, and includes fiberglass exposure data.
• http://monographs.iarc.fr/ENG/Monographs/vol81/mono81.pdf - the article (large PDF over 6MB)
  http://monographs.iarc.fr/ENG/Monographs/vol81/mono81-6A.pdf - article details
  http://monographs.iarc.fr/ENG/Monographs/vol81/mono81-6C.pdf - studies of cancer in experimental animals in re vitreous fibers such as fiberglass;
  http://monographs.iarc.fr/ENG/Monographs/vol81/mono81-6E.pdf - summary of data reported & evaluation
  http://monographs.iarc.fr/ENG/Monographs/vol81/mono81-6F.pdf for the article references
  To search the IARC monographs on various environmental concerns and carcinogens, use http://monographs.iarc.fr/ENG/Monographs/PDFs/index.php

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More Information on Building Diagnostic Inspections and Repairs

For more information about fiberglass as an indoor air quality concern see:

• Fiberglass in Indoor Air, HVAC Ducts, and Building Insulation
• Asbestos Identification in Buildings: How to find & identify asbestos-containing materials
• Asbestos in Good Condition
• Mold in Fiberglass, when, why, and how fiberglass becomes a reservoir of problem mold in buildings.

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