Understanding Their Origins, Uses, and the 2026 Regulatory Deadline
For decades, polychlorinated biphenyls (PCBs) embodied everything industry sought in a fluid: stability, flame resistance, low volatility, and electrical insulation. These qualities explain their success and why, nearly half a century after they were banned in Canada, they remain a current issue.
From a Laboratory Discovery to an Industrial Product
German chemists Hugo Schmidt and Georg Schultz first synthesized PCBs in 1881 by chlorinating biphenyl. Large-scale production, however, did not begin until much later: the Swann Chemical Company began manufacturing them industrially in 1929, and then Monsanto acquired the company in 1935 and marketed various mixtures under the name Aroclor.
An Aroclor is not a single molecule, but a mixture of several congeners—that is, PCBs in which the number and position of the chlorine atoms vary. For most Aroclors, the last two digits indicate the approximate mass percentage of chlorine: 1242 corresponds to about 42%, 1254 to 54%, and 1260 to 60%. The higher this value, the heavier, more viscous, and less volatile the mixture tends to be.
Where Do You Still Find PCBs?
Their stability and low flammability made them ideal for use as insulating and heat-transfer fluids in transformers and capacitors. Buildings and equipment dating from before the 1980s therefore warrant special attention: oil-filled transformers, capacitors, fluorescent lamp ballasts, and certain electrical appliances may still contain them. PCBs have also been added to paints, caulking and sealing products, as well as asphalt, particularly to improve flexibility and resistance to fire or corrosion.
Stability That Has Become a Global Problem
In the environment, PCBs resist degradation for decades. Although they are poorly soluble in water but highly soluble in fats, they accumulate in living tissues, and their concentration can increase as they move up the food chain. Some also travel long distances through the air, water, and particulate matter. Uncontrolled burning can also produce highly carcinogenic dioxins and furans. This combination of persistence, bioaccumulation, and toxicity has led to their inclusion among the persistent organic pollutants covered by the Stockholm Convention.
December 31, 2026: A Deadline to Prepare For
In Canada, the phase-out of several categories of equipment containing PCBs is set for December 31, 2026. The deadline applies in particular to certain equipment containing between 50 and less than 500 mg/kg of PCBs, pole-mounted ballasts and transformers containing 50 mg/kg or more, as well as various types of equipment used in electricity generation, transmission, or distribution. Continued use may be permitted under certain circumstances, subject to ministerial approval; certain authorized activities are also exempt.
Decommissioning is only the beginning: the equipment and fluids may be subject to storage, labelling, disposal, and reporting requirements. For asset owners, the best course of action is to identify at-risk equipment, confirm the concentrations, and plan a compliant disposal process. In the next installment, we’ll explore how dechlorination can destroy PCBs, recover oil, and extend the transformer’s service life without automatically replacing equipment that is still functional.
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