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Article: PCBs (Polychlorinated Biphenyls)
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- Pollution A to Z
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CopyrightCOPYRIGHT 2004 The Gale Group Inc. This material is published under license from the publisher through the Gale Group, Farmington Hills, Michigan. All inquiries regarding rights should be directed to the Gale Group. (Hide copyright information)
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PCBs (Polychlorinated Biphenyls)
PCBs, known to cause cancer in animals and believed to cause cancer in humans, are among the most widespread and hazardous synthetic pollutants. They comprise a group of 209 structurally similar compounds, so-called
congeners
. The individual congeners differ in the degree of chlorination and the positions of the chlorine atoms in the molecule. They are numbered from one to 209 according to a scheme proposed by Ballschmiter and Zell (hence, the term BZ numbers).
PCBs are obtained by the controlled reaction of biphenyl with elemental chlorine under the
catalytic
influence of iron or iron chloride. The commercial formulations were mixtures of various ...