2012 EPA Research Progress Report
PCB Research Supports Safer Schools
In 2012, EPA researchers completed the first three of five studies they are conducting to answer questions about polychlorinated biphenyls, or “PCBs,” in schools. What they are learning is providing key information to minimize exposures and better protect students, teachers, and others.
PCBs are a structurally similar group of manmade chemicals useful for a variety of applications. Some PCBs, for example, are slippery, making them valuable as industrial lubricants. Heat and flame resistant, they were also used as insulators in transformers, electrical appliances, and fluorescent light fixtures. PCBs were also used as stabilizers in paints, adhesives, and caulking.
PCBs were widely used from 1950 until the late 1970s. Congress banned their use and manufacture in 1976 in the face of growing evidence linking their exposure with adverse human health effects, including cancer, reproductive problems, and neurological development.
While PCB exposures have been greatly reduced, the combination of their previous widespread use and persistence has meant they are still present in the environment. Buildings, including schools, built or renovated between 1950 and 1970 may contain PCBs, particularly in caulking or fluorescent lighting fixtures.
In response to concerns raised by parents, EPA scientists are identifying and evaluating potential PCB sources in schools and advancing a better understand of how people might be exposed. The researchers are also investigating methods to minimize or eliminate PCB emissions in schools.
In 2012, EPA researchers released the results of three studies. The first two studies focused on primary sources (such as caulk and lighting fixtures) and secondary sources (paint, masonry walls, and dust that can absorb PCBs from primary sources) of PCBs in schools. The third study investigated a containment method know as “encapsulation” where PCB sources are covered with a coating material to reduce air and surface concentrations of PCBs.
Results of the studies include:
- Caulk put in place between 1950 and 1979 may contain as much as 30% PCBs and can emit PCBs into the surrounding air. PCBs from caulk may also contaminate adjacent materials such as masonry or wood.
- Fluorescent lighting fixtures that still contain their original PCB-containing light ballasts have exceeded their designed lifespan, and the chance for rupture and emitting PCBs is significant. Sudden rupture of PCB-containing light ballasts may result in exposure to the occupants and may also result in the addition of significant clean-up costs.
- Some building materials (e.g., paint and masonry walls) and indoor dust can absorb PCB emissions and become potential secondary sources. When the primary PCB-emitting sources are removed, the secondary sources often emit PCBs.
- Encapsulation is only effective at reducing air concentrations to desirable levels when PCB content in the source is low. Selecting high-performance coating materials is key to effective encapsulation. Multiple layers of coatings enhance the performance of the encapsulation.