Commercial Uses of PCBs

All PCBs are practically insoluble in water but are soluble in hydrophobic media, such as fatty or oily substances. Commercially, they were attractive because they

• are chemically inert liquids and are difficult to burn,

• have low vapor pressures,

• are inexpensive to produce, and

• are excellent electrical insulators.

As a result of these properties, they were used extensively as the coolant fluids in power transformers and capacitors. Later, they were also employed as plasticizers, i.e., agents used to make plastic materials such as PVC products more flexible, in carbonless copy paper, as de-inking solvents for recycling newsprint, as heat transfer fluids in machinery, as waterproofing agents, and so on. ;

Because of their stability and extensive usage, together with careless disposal practices, PCBs became widespread and persistent environmental contaminants. When their accumulation and harmful effects became recognized, open uses—i.e., those for which their disposal could not be controlled—were terminated. Although North American production of PCBs was halted in 1977, the substances remain in use in some electrical transformers currently in service. As these units are gradually decommissioned, their PCB content usually is stored in order to prevent further contamination of the environment. In the United States, the EPA expected a 90% reduction of PCB use in electrical equipment by 2006. Canada has proposed a phase-out of all PCB uses by 2008. In some locales, stored PCBs are destroyed by incineration, using techniques discussed in Chapter 16. Previously, PCB-containing transformers and capacitors were often just dumped into landfills, and their PCB content was allowed to leak into the ground. Indeed, PCBs were inadvertently released into the environment during their production, their use, their storage, and their disposal.

Continue reading here: PCBs Cycling Among Air Water and Sediments

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