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Caulk in Buildings Could Contain not only PCBs, but also Asbestos


EMSL Analytical wants property owners and environmental professionals to be aware of the risks.

Westmont, NJ

Recently the U.S. Environmental Protection Agency (EPA) announced new guidance to communities on PCBs in caulk from buildings constructed or renovated between 1950 and 1978. PCBs are not the only dangers that can be found in old caulk, asbestos caulking was widely used in the construction industry as a sealant, adhesive and as a patching material for cracks, seams and gaps in construction. Caulk as a construction material is widely used in all types of construction and asbestos-containing caulk was a highly ubiquitous substance.

Before safety rulings made its inclusion in construction materials illegal in the late 1970s, caulk manufacturers often used asbestos due to its beneficial fire resistance, strength and insulative properties. Before the 1970s, all types of asbestos, including Amphibole asbestos, were used in caulk formulas. Some caulks can be close to 100 percent asbestos, however most caulks contained 25% asbestos.

After the 1970s, the predominant type of asbestos in caulk compounds was Chrysotile. When first applied in its semi-liquid state, it was essentially as harmless as any other caulking material. However, over time and especially with exposure to the weather, air, and other environmental elements, caulking of any material breaks down and becomes brittle. As the material naturally degrades small asbestos fibers may be released into the air, especially when caulking is used around window or door seams which are subject to disturbance from vibration and air erosion.

Caulk samples containing more than one percent (1%) asbestos is considered a Category I Nonfriable Regulated Asbestos Containing Material (RACM) by the US EPA NESHAP (1990). “Caulk presents a difficult analytical challenge to asbestos laboratories due to the presence of organic matrix materials due to the problem of coating and obscuring asbestos fibers present with opaque matter which can inhibit detection, yielding a false negative result,” reported Robert DeMalo, Senior Vice President, Laboratory Services at EMSL Analytical. “For this reason, several regulatory agencies, including the US EPA and NYS ELAP, recommend matrix modification steps to improve the ability of the laboratory in detecting asbestos in an organic matrix such as caulk.”

The gravimetric reduction preparation technique as described in EPA/600/R-93/116 section 2.3 should be followed for caulk samples followed by analysis via Polarized Light Microscopy (PLM). If the PLM results yield concentrations of one percent (1%) or less asbestos, then the sample should then proceed to analysis via Transmission Electron Microscopy (TEM).

EMSL has been a leader in providing asbestos testing solutions since 1981. To learn more about asbestos testing in caulk and other materials please visit, email or call (800) 220-3675.

About EMSL Analytical, Inc.
EMSL Analytical is a nationally recognized and locally focused provider of environmental, food, and materials testing services and products to professionals and the general public. The company has an extensive list of accreditations from leading organizations as well as state and federal regulating bodies.


 Caulk PCBs Asbestos
 property owners risks
 EPA construction sealant
 adhesive patch material
 amphibole chrysotile RACM

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