ARCHIVED REPORTS_2010-2015 - Laserfiche WebLink

Home Browse Search

:rw � W�. � �. d a•tslls.c �. - Polychlorinated Biphenyls PCBs (polychlorinated biphenyls) have been widely used since the 1930s, because of their excellent electrical- and temperature -insulating abilities. For many years, PCBs were considered to be al- most non-toxic, since there were veryfew reports of Xness even among industrial workers who were exposed to fairly large amounts. In 1978, the Enviro tal Protection Agency (EPA) began to im- pose bans on PCB manufacturing and sales and on most PCB uses. Nevertheless, it is still possible for workers to be exposed to PCBs, either through servicing and handling equipment that contains PCBs, or as a result of leaks, spills, and fires. Tars fact sheer answers some of the most frequently Wd questions about PCBs. The toxic effects of PCBs first drew attention in 1968, when over 1200 people in Japan were poisoned byeating food cooked in oil that was heavily contaminated with PCBs and other chemicals. This caused illnesses which became known as Yusho (rice oil) disease. Soon afterward, studies showed that PCBs cause cancer in test animals. Therefore, it is considered likely that PCBs can cause cancer in humane But why were PCBs banned, while many other chemicals which also cause cancer in test animals were not? PCBs remain in the environment for a long time, because they do not break down. Also, their elimination from the body is very slow, so that levels in body tissues may increase with time. Thus, PCBs build up in the food chain, so that the fish and animals we eat could contain significant amounts. In short, the thing that sets PCBs apart from her equally toxic industrial chemicals is the f\ ability of PCBs to persist in the environment and accumulate in the body and the food chain. PCBs were used mainly in electrical trans- formers and capacitors, heat transfer systems, and hydraulic systems. They were also used in inks and carbonless copy paper and for a variety of other purposes, but the EPA ban now proL• ibits almost all of these other uses Nowadays, PCBs are found mostly in transformers and capacitors. These may be contained in industrial equipment (such as welding equipment), medical equipment (such as X-ray chines), and household appliances (such as refrigerators and microwave ovens). The ballasts of some fluorescent light fixtures contain PCBs. During normal operation of a fluorescent light, the PCBs are entirely enclosed, d you cannot be exposed to them. However, when the capacitor wears out, sometimes it may burn or break and leak PCBs.