How are PCBs classified?
PCBs can be single-sided (one copper layer), double-sided (two copper layers on both sides of one substrate layer), or multi-layer (outer and inner layers of copper, alternating with layers of substrate).
What are polychlorinated biphenyls used for?
PCBs were used widely in electrical equipment like capacitors and transformers. They also were used in hydraulic fluids, heat transfer fluids, lubricants, and plasticizers. The primary company that made PCBs in the United States was Monsanto Inc., mainly using the name Aroclor.
What are polychlorinated biphenyls found in?
Products that may contain PCBs include:
- Transformers and capacitors.
- Electrical equipment including voltage regulators, switches, re-closers, bushings, and electromagnets.
- Oil used in motors and hydraulic systems.
- Old electrical devices or appliances containing PCB capacitors.
- Fluorescent light ballasts.
- Cable insulation.
How is polychlorinated biphenyls made?
PCB Mixtures and Trade Names With few exceptions, PCBs were manufactured as a mixture of individual PCB congeners. These mixtures were created by adding progressively more chlorine to batches of biphenyl until a certain target percentage of chlorine by weight was achieved.
Are polychlorinated biphenyls volatile?
PCBs are either oily liquids or solids and are colorless to light yellow. Some PCBs are volatile and may exist as a vapor in air. They have no known smell or taste. PCBs enter the environment as mixtures containing a variety of individual chlorinated biphenyl components, known as congeners, as well as impurities.
What are the health effects of PCBs?
Studies of PCBs in humans have found increased rates of melanomas, liver cancer, gall bladder cancer, biliary tract cancer, gastrointestinal tract cancer, and brain cancer, and may be linked to breast cancer. PCBs are known to cause a variety of types of cancer in rats, mice, and other study animals.
What is the definition of polychlorinated biphenyl ( PCB )?
Definition of polychlorinated biphenyl. : any of several compounds that are produced by replacing hydrogen atoms in biphenyl with chlorine, have various industrial applications, and are toxic environmental pollutants which tend to accumulate in animal tissues. — called also PCB.
How are polychlorinated biphenyls used in electrical equipment?
Polychlorinated Biphenyls (PCBs) is the common name for a family of chlorinated organic chemicals that contain many individual compounds with varying levels of toxicity. Because of their insulating and thermal stability properties, PCBs have been widely used as coolants and lubricants in transformers, capacitors and other electrical equipment.
How are polychlorinated biphenyls found in sediment?
Polychlorinated biphenyls (PCBs) were only analyzed on sediments as these are primarily transported in association with fine-grained mineral and organic solids. Concentrations of the seven toxic PCBs congeners on sediment were below the detection limit of 10 μg kg −1.
Why was polychlorinated biphenyls banned in the US?
Polychlorinated biphenyls (PCBs) are a group of industrial chemicals that were manufactured through the 1970s, at which point they were banned due to concerns about their adverse effects on humans and the environment, their enrichment in top predators, persistence, and long-range transport.