pcb prototype in ronpcb.com

What Are Polychlorinated Biphenyls (pcbs)?
Polychlorinated biphenyls (PCBs) are mixtures of up to 209 individual chlorinated compounds (known as congeners). There are no known natural sources of PCBs since PCBs are no longer produced in the United States Prototype PCB, but they are still found in the environment. PCBs are either oily liquids or solids that are colorless to light. Some PCBs can exist as a vapor in air. PCBs have no known smell or taste. Many commercial PCB mixtures are known in the U.S. by the trade name Aroclor. PCBs have been used as coolants and lubricants in transformers, capacitors and other electrical equipment because they don't burn easily and are good insulators.

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; and burning of some wastes in incinerators. 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. PCBs also bind strongly to soil. 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 Rigid flex PCB. 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. Studies in exposed workers have shown changes in blood and urine that may indicate liver damage. 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.

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.
Related Links