What are PCB risks associated with legacy transformer oils?

Legacy transformer oils manufactured before the late 1970s may contain polychlorinated biphenyls (PCBs), which are toxic, persistent environmental pollutants. PCB exposure is linked to cancer, neurological damage, and immune system disorders. These oils pose serious risks during leaks, fires, or improper disposal. Because PCBs bioaccumulate and do not easily degrade, contaminated equipment and soil require specialized handling and remediation under strict environmental regulations.