Why must PCB content in transformer oil be strictly controlled?

PCBs are persistent toxic chemicals with serious environmental and human health concerns, and many jurisdictions heavily restrict their use, handling, and disposal. Even low level PCB contamination can trigger regulatory obligations such as special labeling, worker protection, transport documentation, spill response requirements, and disposal via licensed hazardous waste processes. Strict PCB control reduces legal risk, cleanup cost, and liability in case of leaks. It also prevents cross contamination of oil processing equipment and storage tanks, which can spread the problem to otherwise clean assets and complicate routine maintenance and recycling programs.