PCBs (polychlorinated biphenyls) were used for decades by electrical utilities as a fire retardant in the insulating oil in electrical equipment.
In the 1970s, concerns were raised about the safety of PCBs. Detroit Edison ceased purchasing any new PCB-containing equipment in 1976, before the passage of a law defining this substance as “toxic.”
We removed all PCB-containing equipment from public access areas in July of 1984 – four years ahead of the federal deadline and as part of EPA Region V's PCB Phasedown program, we removed from service the 13,000 PCB capacitors in Detroit Edison substations by 2004.
We continue phasing out equipment with oil that is classified as “containing” or “contaminated” by PCBs. That equipment is converted to “non-PCB” through retirement, retrofitting, or replacement.