What is the meaning of polychlorinated biphenyls?
Polychlorinated biphenyls (PCBs) is a group of organic compounds used in the manufacture of plastics, as lubricants, and dielectric fluids in transformers, in protective coating for wood, metal and concrete, and in adhesives, wire coating and so forth.
What was polychlorinated biphenyl 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 characteristics of PCBs?
PCBs are a group of man-made organic chemicals consisting of carbon, hydrogen and chlorine atoms. The number of chlorine atoms and their location in a PCB molecule determine many of its physical and chemical properties. PCBs have no known taste or smell, and range in consistency from an oil to a waxy solid.
When were polychlorinated biphenyls used?
1929
PCBs, valued for chemical stability and fire resistance, were manufactured and processed primarily for use as insulating fluids and coolants in electrical equipment and machinery from 1929-1977.
How many types of polychlorinated biphenyls are there?
About 130 different individual PCBs are found in commercial PCB products.
How are humans exposed to PCBs?
Since PCBs are found throughout the environment, it is likely that everyone has been exposed to them. Persons living near a hazardous waste site with PCB contamination may be exposed to higher levels. PCBs can enter the body by eating or drinking contaminated food, through the air we breathe, or by skin contact.
What are PCBs and why are they toxic?
PCBs, or polychlorinated biphenyls, are highly toxic industrial compounds. They pose serious health risks to fetuses, babies and children, who may suffer developmental and neurological problems from prolonged or repeated exposure to small amounts of PCBs. These chemicals are harmful to adults as well.
What are the effects of PCBs on humans?
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 do PCBs do to humans?
What type of toxin is polychlorinated biphenyls?
The polychlorinated biphenyls (PCBs) are synthetic organochlorine chemicals that were useful industrial products in the past, but their production was ended because they persist in both the environment and living organisms.
What is PCB toxic?
What are the safety guidelines for exposure to PCBs?
Personal protective equipment should be provided to prevent skin and eye contact as well as to control respiratory exposure. Skin protection can usually be achieved by wearing non-porous gloves, gauntlets, boots or shoe protection, and aprons or heavy overalls.
What is the generic structure of polychlorinated biphenyls?
Polychlorinated biphenyls (PCBs) are a group of industrial chemicals that have not been found to occur naturally. The generic structure of PCBs is shown in Figure 1, and consists of biphenyl chlorinated in one or more positions.
How are polychlorinated biphenyls used in everyday life?
Due to their non-flammability, chemical stability, high boiling point and electrical insulating properties, PCBs were used in hundreds of industrial and commercial applications including: Electrical, heat transfer and hydraulic equipment Plasticizers in paints, plastics and rubber products Pigments, dyes and carbonless copy paper
How are polychlorinated biphenyls resistant to oxidation?
PCB mixtures are resistant to acids, bases, oxidation, hydrolysis, and temperature change. They can generate extremely toxic dibenzodioxins and dibenzofurans through partial oxidation. Intentional degradation as a treatment of unwanted PCBs generally requires high heat or catalysis (see Methods of destruction below).
Where does polychlorinated biphenyl ( PCB ) accumulation take place?
Because of their low vapour pressure, PCBs accumulate primarily in the hydrosphere, despite their hydrophobicity, in the organic fraction of soil, and in organisms. The hydrosphere is the main reservoir. The immense volume of water in the oceans is still capable of dissolving a significant quantity of PCBs.