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PCBs in Caulk in Older Buildings

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PCBs in Caulk Hotline

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PCB Guidance Reinterpretation

Important Resources

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In recent years, EPA has learned that caulk containing potentially harmful polychlorinated biphenyls (PCBs) was used in many buildings, including schools, in the 1950s through the 1970s. Most schools and buildings built after 1979 do not contain PCBs in caulk. On September 25, 2009, EPA announced new guidance for school administrators and building managers with important information about managing PCBs in caulk and tools to help minimize possible exposure. Through EPA PCB Regional Coordinators, the Agency will also assist communities in identifying potential problems and, if necessary, developing plans for PCB testing and removal.

For more information:

The EPA is conducting research to address several unresolved scientific questions that must be better understood to assess the magnitude of the problem of PCBs in caulk and identify the best long-term solutions. For example, the link between the concentrations of PCBs in caulk and PCBs in the air or dust is not well understood. The Agency is doing research to determine the sources and levels of PCBs in schools and to evaluate different strategies to reduce exposures. The results of this research will be used to provide further guidance to schools and building owners as they develop and implement long-term solutions. Read more about Research on PCBs in Caulk.

EPA has calculated prudent public health levels that maintain PCB exposures below the “reference dose” – the amount of PCB exposure that EPA does not believe will cause harm. Read Public Health Levels for PCBs in Indoor School Air || PDF version (2 pp, 14 KB)


Caulk is a flexible material used to seal gaps to make windows, door frames, masonry and joints in buildings and other structures watertight or airtight. At one time caulk was manufactured to contain PCBs because PCBs imparted flexibility.

First Step: Take Steps to Minimize Exposure

Although this is a serious issue, the potential presence of PCBs in schools and buildings should not be a cause for alarm. If your school or building was built or renovated between 1950 and 1979, there are several steps schools can take to reduce potential exposure until it can be determined with certainty if PCBs are present in caulk used in the building and any contaminated caulk can be removed. One of the most important steps is to minimize the potential for PCBs to be present in the indoor air. Indoor air levels of PCBs within a school can be reduced by ensuring that the ventilation system is operating as designed, and to repair or improve the system if it is not.

Many old lighting systems contain ballasts manufactured with PCBs. These PCBs can get into the air if the ballast fails or ruptures. Replacement of old lighting systems with new, energy efficient systems will eliminate a potential source of PCBs.

Other steps include:

EPA also has developed an informational brochure to provide the general public with important information on PCBs in building caulk, Preventing Exposure to PCBs in Caulking Material || PDF version (4 pp, 2.7 MB) || en Español (PDF) (4 pp, 2.7 MB), EPA Publication EPA-747-F-09-005.

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If school administrators and building owners are concerned about potential PCBs in the caulk, they should consider testing to determine if PCBs are present in the air. If testing reveals PCB levels above the levels EPA has determined to be safe, schools should attempt to identify any potential sources of PCBs that may be present in the building, including testing samples of caulk and looking for other potential PCB sources (e.g., old transformers, capacitors, or fluorescent light ballasts that might still be present at the school).

If elevated levels of PCBs are found in the air, schools should also have the ventilation system evaluated to determine if it is contaminated with PCBs. Although the ventilation system is unlikely to be an original source of PCB contamination, it may have been contaminated before other sources of PCBs were removed from the school and may contribute to elevated air levels of PCBs. Contaminated ventilation systems should be carefully cleaned.  Ideally, such cleaning should be planned in concert with removal of any sources of PCBs that are found to avoid re-contamination of the system.

During the search for potential sources, schools should be especially vigilant in implementing practices to minimize exposures and should retest to determine whether those practices are reducing PCB air levels. It is important to note that interior surfaces and settled dust can absorb PCBs from contaminated air, and these “secondary sources” can emit PCBs after the primary source is removed. Therefore, a remediation plan should consider the potential effects for these secondary sources on indoor air quality.

Other Sources, Including Caulk

Should those practices not reduce exposure, caulk and other known sources of PCBs (e.g., paints, floor and ceiling tiles) should be removed as soon as practicable. Please note that you cannot tell if caulk has PCBs by looking at it. While it is possible that PCBs could be released into the environment through the cracking or flaking of caulk, EPA believes the old caulk that is still flexible or is in visibly good condition could be a significant source of PCBs into the air. The only way to be sure that caulk has PCBs is to have a professional test the caulk.

Where schools or other buildings were constructed or renovated between 1950 and 1979, EPA recommends that PCB-containing caulk be removed during planned renovations and repairs (when replacing windows, doors, roofs, ventilation, etc.).

Based on EPA's Office of Research and Development's (ORD) laboratory research, encapsulation was found to be most effective for interior surfaces that contain low levels of PCBs (i.e. several hundred parts per million). Depending on the PCB reduction goal, the performance of the encapsulant, and the conditions of the building, the upper limit of the PCB concentration for successful encapsulation may vary. Therefore, post-encapsulation monitoring is an essential part of the encapsulation process. Building owners should consult EPA's research on this issue for more specifics. Encapsulation may be useful for the reduction of emissions from secondary sources such as contaminated building materials under and around PCB-containing caulk or paint that has been removed. Encapsulation was not found to be effective in reducing emissions from sources that have a high PCB content (for example caulk) for more than a short period of time. Because each site will present unique circumstances, please consult your EPA PCB Regional Coordinator regarding the application of encapsulation measures on a case by case basis. It is critically important to assure that PCBs are not released to air during replacement or repair of caulk in affected buildings. Assessment of the ventilation system for potential contamination, proper cleaning when required, and isolation of the system to prevent further contamination are also important.

Test Methods

For determining the presence of PCBs in indoor air, EPA has two approved methods:

EPA recommends that caulk suspected to contain PCBs be tested directly for the presence of PCBs and removed if PCBs are present at significant levels. The PCB regulations provide appropriate methods for testing. More information on these procedures can be found at:

Contact EPA's Toxic Substances Control Act (TSCA) Hotline at 1-888-835-5372 or the EPA PCB Regional Coordinator for your state for assistance.

Schools Information Kit

A Schools Information Kit provides information for parents, students and staff about PCBs in caulk, including:

Information for Contractors Working in Older Buildings

Read Contractors Handling PCBs in Caulk During Renovation, EPA's guidance to contractors and maintenance personnel working in older buildings that may contain PCB-contaminated caulk.

Read EPA's Steps to Safe Renovation and Abatement of Buildings that Have PCB-Containing Caulk.

Additional Information

Additional EPA brochures and fact sheets on best practices for addressing PCBs in caulk:

Where Can I Get More Information?

For more information on how to properly test for and address PCBs in caulk, call the EPA's Toxic Substances Control Act (TSCA) Hotline at 1-888-835-5372 or contact the EPA PCB Regional Coordinator for your state.


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