The University at Albany NIEHS Basic Research Program has focused on the problems related to PCB exposure to residents of the Akwesasne Nation located on the junction of Ontario, Quebec and New York state. Among the thousands of contaminants found in the environment, few are as well recognized or more feared by the public than polychlorinated biphenyls (PCBs). These compounds have contaminated thousands of miles of rivers and streams throughout the world including miles of the Hudson and St. Lawrence Rivers of New York, and dozens of marine and fresh water harbors of both coasts and the Great Lakes. Removal of PCBs from the environment are estimated to cost billions of dollars in the U.S. alone. Remediation costs for removal and treatment or isolation of this pollutant from sections of the Hudson and St. Lawrence are estimated to be about $1 billion!
PCBs are a class of chlorinated organic compounds manufactured by Monsanto during the 1930s to late 1970s. These substances were widely used throughout the world until health officials and researchers began to suspect that the compounds caused serious human health effects. During the approximate 40 years of production, more than 700,000 tons of PCBs were manufactured in North America. Because of its unique heat resistance and electrical characteristics, the compound was widely used as an additive in transformer and hydraulic fluids and continues to be used in a variety of applications throughout the world.
This class of contaminants is made up of multiple compounds. Individual aroclors can consist of more than 200 individual chemicals, each with a different number and arrangement of chlorines around a central carbon double ring, or biphenyl. PCBs in the environment can include 70-90 unique chlorinated compounds or congeners, each with their own characteristics and behavior.
Even though this class of contaminants is considered to be insoluble in water and was not thought to readily volatilize to the atmosphere, the compound is found in remote areas of the world, thousands of miles from sources. That means the compound is highly mobile and can be readily transported by water and air. In comparison to many other contaminants, PCBs are relatively insoluble in water, yet can be found in almost every living organism on Earth, including humans.
The PCB molecule is comprised of a central carbon biphenyl (above in red) with a variable number (1-10) of attached chlorines (Cl). The number and positions of the chlorines varies creating 209 possible compounds or congeners. The PCB depicted above is a dichlorobiphenyl or a PCB with two chlorines attached to the biphenyl ring.
