Saturday, 01 November 2014

Asbestos in Asphalt Shingles

Historically, asbestos has been used as an ingredient in several different asphalt roofing products. In 1990, U.S. EPA published a notice in the Federal Register (55 FR 5144, Feb. 13, 1990) identifying products made with asbestos. The Asbestos NESHAP regulation lists the following asphalt roofing products as possibly containing asbestos (40 CFR 61 Subpart M, Appendix A):
  • Built-up roofing
  • Asphalt-containing single ply membrane systems
  • Asphalt shingles
  • Asphalt-containing underlayment felts
  • Asphalt-containing roof coatings and mastics
  • Asphalt-containing base flashings
In reality, while asbestos was commonly used in many asphalt roofing materials, asbestos was rarely used in the shingles themselves. It is acknowledged by the asphalt shingle manufacturers that between 1963 and the mid 1970s, some manufacturers did use asbestos in the fiber mat of shingles. Manufacturer information on how many asbestos-containing shingles were sold is not available, but the amount of asbestos used in shingles was typically less than 1% [NESHAP defines ACM as any material containing more than 1% asbestos]. and it was only in a small portion of the manufacturers' production. Unfortunately, less is known about the possible presence of asbestos in imported roofing coatings.
Because of concerns raised over the possible presence of asbestos in asphalt shingles, several shingle recyclers have done extensive testing to confirm that asbestos is not a concern. The Construction & Demolition Recycling Association (CDRA) has compiled (and continues to compile) a database of test results for asbestos in asphalt shingles. These test results come from facilities that recycle asphalt shingles and from exploratory testing. Individuals interested in the raw data should contact the CDRA. In addition, individuals with additional sampling data are greatly encouraged to share the results with the CDRA so the information can be posted on this webpage. CDRA is especially interested in analyses utilizing the transmission electron microscopy (TEM) method. Post Consumer Shingles
It is noted that samples of built-up roofing, roofing mastics, roofing felts and other asphalt roofing products other than shingles have been shown to contain asbestos. Below is an overview of sampling results for asphalt shingles gathered to date.
Iowa

A construction and demolition debris recycler in Iowa has sampled loads of shingles since 1999. The shingles are sampled by taking random grab samples from a load and having a laboratory analyze for asbestos using polarized light microscopy (PLM). Out of a total of 1791 samples tested, none was found to have detectable levels of asbestos.

Maine

An asphalt shingle recycler in Maine (see case study) tested 118 samples. Representative composite samples were collected on a per-incoming-load basis and analyzed using PLM. None of the samples was found to contain asbestos.

Massachusetts

An asphalt shingle recycler in Massachusetts tested incoming asphalt shingles on a per-load basis. A total of 2,288 composite, representative samples were taken from the incoming product. Samples were analyzed using PLM. Twelve samples contained asbestos, but 11 contained less than 1% [NESHAP defines ACM as any material containing more than 1% asbestos]. The twelfth sample had 2% asbesto.  These results, as defined by NESHAP, show only 1 in 2, 288 samples had sufficient asbestos to categorize it as ACM. Samples were also collected from the tarpaper and the outgoing finished product and analyzed using PLM. Out of 69 tarpaper samples, two contained over 5% asbestos and two contained less than 1% asbestos.  Out of 109 finished, outgoing product samples, two contained less than 1% asbestos. (see "Asbestos analysis of Post-Consumer Asphalt Shingle Waste")

Missouri

Testing results were provided by the Missouri Division of Environmental Quality. During an asbestos survey, six shingle samples were collected and analyzed with PLM. No asbestos was detected.

Florida

Shingle testing was completed as a part of the "Roof to Roads" project. Two hundred and eighty-seven samples were taken of incoming shingles: 2 tested above 1% for asbestos. Seventeen samples were also taken during the shingle grinding process. None of the samples had asbestos over 1%.

 

Last Updated: ( Wednesday, 08 May 2013 )