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Polychlorinated biphenyls (PCBs) are a class of organic compounds with 1 to 10 chlorine atoms attached to biphenyl which is a molecule composed of two benzene rings each containing six carbon atoms. The chemical formula for all PCBs is C12H10-xClx. PCBs were used as coolants and insulating fluids for Transformers and capacitors, stabilizing additives in flexible PVC coatings of electrical wiring and electronic components, pesticide extenders, cutting oils, flame retardants, hydraulic fluids, sealants (used in caulking, etc), adhesives, wood floor finishes,[1] paints, de-dusting agents, and in carbonless copy paper.[2] PCB production was banned in the 1970s due to the high toxicity of most PCB congeners and mixtures. PCBs are classified as persistent organic pollutants which bioaccumulate in animals.
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Where would you find PCBs?
One place you're likely to find them in high concentrations is inside older transformers (the large, oil-filled ones used on power lines). (I'm assuming, since this is in Chemistry, you mean "polychlorinated biphenyls" and not "printed circuit boards.")
What are PCBs used for?
Completely colorless to light, polychlorinated biphenyls (PCBs)are a compound mixture of over 200 different congeners. PCBs are no longer being produced because of the harmful contaimination toxicity that can occur but at one time the mixture was commercially produced for electrical equipment like transformers and capacitors because of the ability for PCBs to act as insulators since they do not burn easily. The manufacture of PCBs was stopped in the U.S. in 1977 because of evidence that PCBs build up in the environment and could cause harmful health effects. Items such as fluorescent light fixtures that were produced prior to 1977 may be a potential for PCB contamination.What happens to PCBs when they enter the environment?PCBs entered air, water and soil during their manufacture, use and disposal; from accidental spills and leaks during their transport; and from leaks or fires in products containing PCBs. PCBs can still be released to the environment from hazardous waste sites; illegal or improper disposal of industrial wastes and consumer products; leaks from old electrical transformers containing PCBs; also incinerating some wastes. PCBs do not readily break down in the environment and thus may remain there for very long periods of time. PCBs can travel long distances in the air and be deposited in areas far away from where they were released.While water contamination can occur, many PCBs dissolve or stick to the bottom sediments or attach themselves to organic particles. Similarly, soil is another compound that PCBs bind to. PCBs are taken up by small organisms and fish and they are also taken up by other animals that eat these aquatic animals as food. PCBs accumulate in fish and marine mammals, reaching levels that may be many thousands of times higher than in water.How might I be exposed to PCBs?Exposure to PCBs may occur if old fluorescent lighting fixtures and electrical devices and appliances, such as television sets and refrigerators, that were made 30 or more years ago, are used. These fixtures, devices, and appliances may leak small amounts of PCBs into the air when they get hot during operation and also could be a source of skin exposure.People can be exposed to PCBs by eating contaminated food. The main dietary sources of PCBs are fish (especially sport fish caught in contaminated lakes or rivers), meat and dairy products. Another way to become exposed to PCBs is through contaminated well water or air near a waste site. Employees may be exposed to PCBs. In the workplace during repair and maintenance of PCB transformers; accidents, fires or spills involving transformers, fluorescent lights and other old electrical devices; and disposal of PCB materials.How can PCBs affect my health?Acne-like skin rashes are a side effect of PCBs exposure in adults, for children, the side effects are much worse seriously affecting neurobehavioral and immunological changes. PCBs are known to cause cancer in animals.The most commonly observed health effects in people exposed to large amounts of PCBs are skin conditions such as acne and rashes. Liver damage may occur in exposed workers and can be found when testing blood and urine levels. PCB exposure in the general population is not likely to result in skin and liver effects. Most of the studies of health effects of PCBs in the general population examined children of mothers who were exposed to PCBs.Animals that ate food containing large amounts of PCBs for short periods of time had mild liver damage and some died. Animals that ate smaller amounts of PCBs in food over several weeks or months developed various kinds of health effects, including anemia; acne-like skin conditions; and liver, stomach and thyroid gland injuries. Other effects of PCBs in animals include changes in the immune system, behavioral alterations, and impaired reproduction. PCBs are not known to cause birth defects.How likely are PCBs to cause cancer?Few studies of workers indicate that PCBs were associated with certain kinds of cancer in humans, such as cancer of the liver and biliary tract. Rats that ate food containing high levels of PCBs for two years developed liver cancer. The Department of Health and Human Services (DHHS) has concluded that PCBs may reasonably be anticipated to be carcinogens (substances that cause cancer). The Environmental Protection Agency (EPA) and the International Agency for Research on Cancer (IARC) have determined that PCBs are probably carcinogenic to humans.Is there a medical test to show whether I've been exposed to PCBs?Tests exist to measure levels of PCBs in your blood, body fat, and breast milk, but these are not routinely conducted. Most people normally have low levels of PCBs in their body because nearly everyone has been environmentally exposed to PCBs. The tests can show if your PCB levels are elevated, which would indicate past exposure to above-normal levels of PCBs, but cannot determine when or how long you were exposed or whether you will develop health effects.Has the federal government made recommendations to protect human health from exposure to PCBs?The EPA has set a limit of 0.0005 milligrams of PCBs per liter of drinking water (0.0005 mg/L). Reports to the EPA of PCB spill or accidental releases of 1 or more pounds must occur. The Food and Drug Administration (FDA) requires that infant foods, eggs, milk and other dairy products, fish and shellfish, poultry, and red meat contain no more than 0.2-3 parts of PCBs per million (0.2-3 ppm). Many states have established fish and wildlife consumption advisories for PCBs
Are PCBs highly biodegradable?
PCBs are considered to be persistant environmental pollutants and thus are not very biodegradable.
Where have PCBs caused widespread skin and systemic disorders?
Western Japan.
What is a Chloride?
Cooper's Chloride is a chemical solution used to etch printed circuit boards (PCBs).
What was the EPA ruling on polychlorinated biphenyls?
EPA had restricted the use of polychlorinated biphenyls (PCBs) as a cooling medium for liquid-filled transformers, due to the flammability and toxicity of the fluid. Less flammable replacements were phasing out the use of PCBs.
What has the author Gregory John Hollod written?
Gregory John Hollod has written: 'Polychlorinated biphenyls (PCBs) in the Lake Superior ecosystem' -- subject(s): Environmental aspects, Environmental aspects of Polychlorinated biphenyls, Pollution, Polychlorinated biphenyls, Water
What does the PCBs stand for and what is it?
PCBs stand for polychlorinated biphenyls, which are a group of man-made chemicals that were used in various industrial applications such as insulating fluids and in sealants. PCBs are now banned in many countries due to their toxic effects on human health and the environment.
Is asbestos a pcb's?
PCBs (polychlorinated biphenyls) are organic chemicals, usually liquid in form. Asbestos is a mineral (a rock). The two are completely different.
What has the author Paul Hauge written?
Paul Hauge has written: 'Polychlorinated biphenyls (PCBs), chlordane, and DDTs in selected fish and shellfish from New Jersey waters, 1988-1991' -- subject(s): Chlordan, DDT (Insecticide), Effect of water pollution on, Environmental aspects, Environmental aspects of Chlordan, Environmental aspects of Polychlorinated biphenyls, Fishes, New Jersey, Polychlorinated biphenyls, Shellfish
What effect do PCB's have on the environment and where were they put first?
PCBs, polychlorinated biphenyls, effect birds similarly to DDT, making it harder for them to lay viable eggs. If burned, they produce dioxin, an extremely dangerous, carcinogenic chemical. The were first used in capacitors, as a dielectric.
What has the author Thomas J Murphy written?
Thomas J Murphy has written: 'Polycholrinated biphenyls in precipitation in the Lake Michigan basin' -- subject(s): Polychlorinated biphenyls, Precipitation (Meteorology) 'Polychlorinated biphenyls in precipitation in the Lake Michigan basin' -- subject(s): Polychlorinated biphenyls, Precipitation (Meteorology)
Why do polar bears have high amounts of polychlorinated biphenyls - PCBs - in their fat?
Polar bears are the top predator in the Arctic food chain, so they absorb all the toxic contaminants from the lower animals. Polychlorinated biphenyls (PCBs) were once used as a cooling fluids and insulators in transformers and electric motors, but were widely contaminating the environment, so in 2004 the international community acted to ban the synthetic chemicals. PCBs dissolve easily in fat, and the mother bears' milk is rich in fat, so this is how they are passed on to the young cubs. PCBs interfere with the bears' thyroid hormones, which are essential to control their temperatures In the freezing Arctic conditions. A study in 2008 showed that amounts of PCBs in Norwegian polar bears have dropped significantly, though they are still at dangerous levels.
What has the author Jeffrey S Steuer written?
Jeffrey S Steuer has written: 'Distribution and transport of polychlorinated biphenyls and associated particulates in the Hayton Millpond, south branch Manitowoc River, 1993-95' -- subject(s): Environmental aspects, Environmental aspects of Polychlorinated biphenyls, Pollution, Polychlorinated biphenyls, Water
What has the author Richard E Besse written?
Richard E. Besse has written: 'Distribution and sources of polychlorinated biphenyls in Woods Inlet, Lake Worth, Fort Worth, Texas, 2003' -- subject(s): Environmental aspects, Environmental aspects of Polychlorinated biphenyls, Lake sediments, Pollution, Polychlorinated biphenyls, Water
What has the author J M O'Connor written?
J. M. O'Connor has written: 'Polychlorinated biphenyl transport in coastal marine foodwebs' -- subject(s): Effect of water pollution on, Environmental aspects, Environmental aspects of Polychlorinated biphenyls, Fishes, Polychlorinated biphenyls
Does Brita's plastic containers contain polychlorinated biphenyls?
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