PCBs

PCBs is the acronym for Polychlorinated biphenyls which are complex chlorinated compounds. In the 1935 Monsanto bought Swann Chemical Company, the company that invented PCBs and became the source of all PCBs in the United States. Monsanto PCB customers like General Electric and Westinghouse also released massive amounts into the environment. 

The Agency for Toxic Substances and Disease Registry (ATSDR) states "There are no known natural sources of PCBs. PCBs are either oily liquids or solids that are colorless to light yellow. Some PCBs can exist as a vapor in air. PCBs have no known smell or taste." 

"PCBs have been used as coolants and lubricants in transformers, capacitors, and other electrical equipment because they don't burn easily and are good insulators. The manufacture of PCBs was stopped in the U.S. in 1977 because of evidence they build up in the environment and can cause harmful health effects. Products made before 1977 that may contain PCBs include old fluorescent lighting fixtures and electrical devices containing PCB capacitors, and old microscope and hydraulic oils," ATSDR states. 

Indeed as the book Our Stolen Future notes PCB's "might be found virtually anywhere imaginable: in the sperm of a man tested at a fertility clinic in upstate New York, in the finest caviar, in the fat of a newborn baby in Michigan, in penguins in Antarctica, in the bluefin tuna served in a sushi bar in Tokyo, in the monsoon rains falling in Calcutta, in the milk of a nursing mother in France, in the blubber of a sperm whale cruising in the South Pacific, in a wheel of ripe brie cheese, in a handsome striped bass landed off Martha’s Vineyard on a summer weekend. Like most persistent synthetic chemicals, PCB’s are world travelers." (Our Stolen Future, p. 91-92)"