Prior to the 1970s, some ballasts - particularly those used to control "High-Output" lamps - contained PCBs. PCBs were a group of compounds with electrical insulating properties, and were found in transformers and other electrical devices. PCBs are also carcinogens, and their use in electrical equipment has been banned since the 1970s, but a ballast made before this date could contain this compound. In these older ballast designs, the PCB compounds could leak out of a ballast if it is overheated or if the ballast case is physically damaged. Newer ballasts are usually marked "NO PCBs" to indicate that they don't contain these compounds even if older models from that manufacturer didn't have any PCBs either.
If a ballast is leaking a clear or light colored oil, it may indicate the presence of PCBs. If the model number and manufacturers name are still on the ballast, contact them and ask if the ballast contained PCBs. The call centers of all ballast manufacturers have the answer to this question for all of their older ballast models. In some companies, you will be transferred to the product safety group of that company who will assist you. If you can't find out if the ballast contains PCBs or find out that it definitely does, wear gloves and clean up the oil with disposable towels. Then replace the ballast with a modern one. The clean-up materials, the old ballast and the gloves should be sent to a hazardous material handler for proper disposal.
