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PCB warning label on a power transformer known to contain PCBs. Polychlorinated biphenyls (PCBs) are organochlorine compounds with the formula C 12 H 10−x Cl x; they were once widely used in the manufacture of carbonless copy paper, as heat transfer fluids, and as dielectric and coolant fluids for electrical equipment. [2]
Congener descriptors give a shorthand notation for geometry and substituent positions. The twelve congeners that display all four of the descriptors are referred to as being "dioxin-like", referring both to their toxicity and structural features which make them similar to 2,3,7,8-tetrachlorodibenzo-p-dioxin (2378-TCDD). [1]
PCB-compounds, always containing low concentrations of dioxin-like PCBs and PCDFs, were synthesized for various technical purposes (see Polychlorinated biphenyls). They have entered the environment through accidents such as fires or leaks from transformers or heat exchangers, or from PCB-containing products in landfills or during incineration.
Test results conducted in the fall showed the presence of PCBs, or polychlorinated biphenyls — toxic, man-made chemicals that were banned from being produced in the United States in 1979.
(Reuters) -A Washington jury on Tuesday ordered Bayer to pay $100 million to four people who say they were sickened by toxic chemicals known as PCBs at a Seattle-area school, but found the company ...
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PCBs are toxic to fish at high doses, and associated with spawning failure at low doses. Human exposure occurs through food, and is associated with reproductive failure and immune suppression. Immediate effects of PCB exposure include pigmentation of nails and mucous membranes and swelling of the eyelids, along with fatigue, nausea, and vomiting.
When a PCB has no components installed, it is less ambiguously called a printed wiring board (PWB) or etched wiring board. [18] However, the term "printed wiring board" has fallen into disuse. A PCB populated with electronic components is called a printed circuit assembly (PCA), printed circuit board assembly or PCB assembly (PCBA). In informal ...