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Lab procedures for fiberglass dust testing: This document provides forensic laboratory procedural details for the laboratory identification of fiberglass hazards in air or in settled dust samples collected in residential and light-commercial buildings.

Readers should see Fiberglass Detection in Building Air and see Fiberglass Fragment Hazards for basic hazard information. Also see our more general articles FIBERGLASS HAZARDS and also Insulation Products MSDS and Fiberglass Insulation Exposure Limits.

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Laboratory Identification of Fiberglass Fibers

Fiberglass fragments in air, dust, or material samples are easily identified in the forensic laboratory using light and polarized light microscopy and common slide preparation techniques. While glass fibers can be identified using Cargill(R) certified refractive index liquids, it is easier and faster to examine fibers prepared in almost any common slide mounting solution by looking for the following features:

• Smooth sided manmade fibers which may appear in a wide variety of diameters and lengths, but with a characteristic concoidal fracture on the fiber end is key in laboratory identification of fiberglass fragments in air samples or settled dust samples from buildings where screening for fiberglass dust is required
• Presence of colored resin binder on fiber lengths or where fibers cross is another identifying characteristic of fiberglass insulation
• The disappearance of these fiberglass fibers from view in a light microscope when viewed with crossed polars also is used to confirm that glass fibers are present
• Presence of concoidal fractures on the ends of fibers is evidence of glass or fiberglass

The two lab photographs of fiberglass insulation just above show, from left, the characteristic concoidal fracture at the end of a fiberglass fiber, and resinous material used as a binder in fiberglass insulation. The resin binder in fiberglass insulation can appear in various colors and which gives fiberglass its individual characteristic color.

Determining the source of fiberglass particles found in a building: It may be possible to identify the manufacturer of or at least the source of fiberglass fibers found in a building by comparing the color of resin identified in the microscope with colors observed by visual inspection of fiberglass installed in different building areas.

Identifying fiberglass resins and mineral wool insulation: The left hand lab photo of fiberglass show below provides two examples of resinous binder in fiberglass insulation at a lower magnification of about 300x, with the left, triangular resin particle having been bound to two intersecting glass fibers.

Notice the considerable variation in fiberglass fiber diameter in this photo - the fibers in this photo might be from different sources as not only are they characteristically different by metrics, but their resins are of different color.

Problems in identifying very small fiberglass fragments in air and dust samples: Our own field investigations find that fiberglass particles are quite common in indoor air. Unless the forensic particle laboratory is making a point of counting small fiberglass fragments in indoor air or dust samples, only a large-particle count may be provided and the presence and potential effects of fiberglass dust may be underestimated. Furthermore, proper lab procedure and use of mountants with an appropriate refractive index to see glass fragments is critical as otherwise such particles may simply be invisible when viewed using conventional slide preparation methods.

Mineral wool insulation: The right hand photo shown below shows displays a resin binder and thin, varying-diameter fibers of glass mineral wool insulation.

Under polarized light using crossed polars, the glass fibers in these photos will simply disappear from view. (photo not shown - phase contrast microscopy or use of special mounting fluids with an appropriate refractive index may be needed especially to identify small fiberglass fragments.)

Photographs of Unbonded Fiberglass Insulation - "Blowing Wools"

Above (left) we show a macro photograph of white blown-in unbonded InsulSafe® building insulation sold by CertainTeed and provided by a homeowner who asked our lab to study dust samples from her home. At above right is the same insulation shown in the stereo microscrope at about 20x, and below the same material is magnified to 720x.

Identifying Contents of House Dust to Screen for Building Insulation

Above (left) we show a 720x micro-photograph of white blown-in unbonded InsulSafe® building insulation sold by CertainTeed. At above right our photo shows the dominant particles in the dust sample from the home under study. Magnified to 720x the fibers we found were primarily cotton, with some linen and a few synthetic fabric fibers. There was virtually none of the insulation fibers provided for comparison (above left) as a possible source of dust in the home.

Above (left) a client photo shows a heavy and rapid dust accumulation on building surfaces. At above right our lab photo shows that the prime contents of the dust were fabric fibers and starch granules, not building insulation in this case. - DF & WW 6/2010.

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Questions & answers about lab procedures for the identification of large & small fiberglass fragments in air & dust samples from buildings.

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  Lab Identification of Fiberglass

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

Books & Articles on Building & Environmental Inspection, Testing, Diagnosis, & Repair

• Our recommended books about building & mechanical systems design, inspection, problem diagnosis, and repair, and about indoor environment and IAQ testing, diagnosis, and cleanup are at the InspectAPedia Bookstore. Also see our Book Reviews - InspectAPedia.
• Environmental Health & Investigation Bibliography - our technical library on indoor air quality inspection, testing, laboratory procedures, forensic microscopy, etc.
• Adkins and Adkins Dictionary of Roman Religion discusses Robigus, the Roman god of crop protection and the legendary progenitor of wheat rust fungus.
• Kansas State University, department of plant pathology, extension plant pathology web page on wheat rust fungus: see http://www.oznet.ksu.edu/path-ext/factSheets/Wheat/Wheat%20Leaf%20Rust.asp
• "A Brief Guide to Mold, Moisture, and Your Home", U.S. Environmental Protection Agency US EPA - includes basic advice for building owners, occupants, and mold cleanup operations. See http://www.epa.gov/mold/moldguide.htm
• US EPA - Mold Remediation in Schools and Commercial Building [ copy on file as /sickhouse/EPA_Mold_Remediation_in_Schools.pdf ] - US EPA
• US EPA - Una Breva Guia a Moho - Hongo [on file as /sickhouse/EPA_Moho_Guia_sp.pdf - - en Espanol

Fiberglass in buildings: hazards, testing, cleanup, prevention: references & products

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

• Asbestos: How to find and recognize asbestos in buildings - visual inspection methods, list of common asbestos-containing materials (Asbestos is not fiberglass and vice versa).
• BASEMENT MOLD includes examples of moldy fiberglass insulation found in basements
• CRAWLSPACE MOLD includes additional examples of moldy fiberglass insulation found in crawl spaces
• Duct System Defects
• Fiberglass in Indoor Air, HVAC ducts, and Building Insulation, Indoor Air Quality Investigations, building insulation and HVAC duct work insulation hazards
• FIBERGLASS HAZARDS
• Fiberglass Particle Identification in the Fiberglass Test Laboratory
• Fiberglass References - Government Agencies & Authorities list of public documents on fiberglass
• Goodman Gray Flex Duct Deterioration and Failures
• INSULATION INSPECTION & IMPROVEMENT
• Insulation Identification Photographs - Fiberglass insulation photos, yellow, pink, green, white fiberglass identification in building attics, walls, ducts, other locations
• Insulation Identification Photographs - Cellulose insulation photos, Mineral wool insulation photos, rock wool insulation photos, cotton insulation photos, balsam wool insulation photos
• Insulation Identification Photographs - Vermiculite insulation photos
• Lab Identification of Fiberglass photographs and text assist in laboratory identification of fiberglass fibers and fragments in air, dust, or material samples in the laboratory using forensic microscopic techniques.
• Mold in Fiberglass building insulation, when, why, and how fiberglass becomes a reservoir of problem mold in buildings.
• AIR FILTERS, OPTIMUM INDOOR
• Owens Corning Flex Duct Deterioration and Failures
• World Trade Center Dust Particle Identification
• 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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