An emerging environmental health issue is information published by the Environmental Protection Agency (US EPA) that caulk containing polychlorinated biphenyls (PCB) was used in many nonresidential buildings, including schools, throughout the 1950s through the 1970s. PCBs are man-made toxic chemicals that persist in the environment and bioaccumulate in animals and humans. Exposure to PCBs can affect the immune system, reproductive system, nervous system, and endocrine system and is potentially cancer-causing. Caulk is used in construction to seal gaps to make windows, door frames, masonry and joints in buildings watertight or airtight. Before the prohibition of PCBs in all U.S.-manufactured products in 1977, caulk was prepared with PCBs due to the flexibility and other valuable properties of the compound such as persistence and low reactivity. Buildings that were constructed or renovated during this period could contain caulking with elevated levels of these hazardous compounds.
Until recently, testing was seldom conducted for PCB levels and there have been few studies to determine the environmental exposures to building occupants, remediation or construction workers, or related environmental contamination. The material will evidently deteriorate and leach PCBs into nearby soil, concrete pads, bricks, mortar, storm drains and potentially volatilize. Studies have shown a correlation between PCBs in caulking and elevated levels of PCBs in indoor air and dust, in addition to ambient soil surrounding the buildings. The deteriorating caulk has the highest potential for creating dust exposing occupants via inhalation. In addition to inhalation from PCBs in the air or dust, dermal exposure may occur when a person comes in contact with the caulk, surrounding porous materials, or PCB-contaminated soil adjacent to buildings.
The US EPA recommends indoor air monitoring to determine if PCB levels exceed the suggested public health levels. If testing reveals PCB levels above these levels, the potential sources of PCBs need to be identified. Typically testing of samples of caulk, dust, and soil is performed. If elevated air levels of PCBs are found, it is also recommended that the ventilation system be evaluated to determine if it is contaminated with PCBs, since it may have been contaminated before other sources of PCBs were removed from the building and may be contributing to elevated air levels. Contaminated ventilation systems need to be decontaminated along with removal of any sources of PCBs that are found to avoid recontamination of the system.
EPA is currently researching PCB exposure related to contaminated caulk and looking into methods for mitigating exposure and potential risks associated with PCBs in caulk. In addition to the risk posed by PCBs caulk can also contain as much as 20 percent asbestos, requiring additional management during sampling and disposal.