Why Are PCBs a Problem?
Although they’re no longer commercially produced, PCBs are still found in products and materials produced before the ban, and they can be released into the environment in a number of ways. They can escape from electrical transformers, be dumped illegally or improperly, or be released from poorly maintained hazardous waste sites, or from landfills not designed to handle hazardous waste.
PCBs can also be released in several different forms, with different effects. If released as a liquid, they can find their way into nearby soil and water. High temperature fires (intentional or unintentional) can turn liquid PCBs into an aerosol form which can be inhaled, or can be transported elsewhere by air currents. If PCBs burn at high temperatures, they can also be converted into far more toxic dioxins and furans.
Because PCBs don’t readily break down, they may cycle between air, water, and soil for a long time. Studies have found that PCBs can be transported by global air currents, and the lighter the form of PCB, the farther it can travel. Trace levels of PCBs have been found all over the world, even in ice, and snow and sea water, far from where they originated.
Low levels of PCBs also make their way from the environment into food. They can accumulate in the leaves and above-ground parts of plants and crops and can also accumulate in the cells of small organisms and fish. Their presence in both food and the environment means that almost everyone has been exposed to low levels of the chemical.