Before EPA banned the manufacture of PCB's in 1978, PCBs were used in the manufacture of fluorescent light ballasts. The use of PCB's in ballasts manufactured prior to 1978 was not regulated by the EPA. All light ballasts manufactured since 1978 which do not contain PCBs should be marked by the manufacturer with the statement "No PCB's". For those manufactured prior to that time , or for those ballasts which contain no statement regarding PCB content, you should assume that they do contain PCB's. If the ballast does contain PCBs, they are located inside the small capacitor. There would be approximately 1 to 101/2 ounces of PCB fluid in the capacitor itself. If the ballast fails, the capacitor may break open, allowing the PCB oil to drip out of the fixture. The capacitor does not always leak when the ballast fails, but when it does happen, measures should be taken to limit or avoid personal exposure.