What is PCB in electronics
Facts about PCB
The industrial synthesis miracle
PCB is a synthetic construction chemical that has been used in a variety of materials. The advantages of this industrial product are its thermal and chemical stability, it is flame retardant and electrically non-conductive. PCB was mainly used as a plasticizer and expansion compound, but also as a coolant, e.g. B. as hydraulic fluid. In its pure form, PCB is practically odorless. The abbreviation PCB stands for polychlorinated biphenyls, a form of chemical chlorine compounds. Depending on the position and the number of chlorine atoms, there are 209 different chlorinated biphenyls.
In its pure form, PCB is a yellowish, practically odorless liquid
|From 1929 industrial syntheses for the production of polychlorinated biphenyls were developed|
Effects on the environment and health
PCB is absorbed through the gastrointestinal tract, through the skin or through inhalation of vapors, is quickly distributed in the body and accumulates in fatty tissue, where it is deposited. PCB is one of the most dangerous environmental toxins of all. Due to the property that PCBs are fat-soluble and do not degrade in the environment, PCBs are distributed globally and continuously accumulate in the food chain. PCB that gets into the environment remains in the food cycle for all eternity! The highest concentrations of PCB were found in sea birds and marine mammals. It leads to sex reassignment in turtle eggs and in the laboratory a reduction in sperm cells, a reduction in litter size and an increased mortality of the young animals has been demonstrated in mice. Also the declining population of z. B. otters, seals and sea lions can be attributed to the high PCB environmental pollution, it weakens the whales and infectious diseases have easy game. As a result, more and more whales are stranded. As a rule, there is no acute, immediate risk of poisoning for humans through PCBs. However, fatal long-term effects could be determined even with small amounts. PCB leads to liver, spleen and kidney damage, affects the sex hormone balance and there is a suspicion of carcinogenic potential. Typical effects are also hair loss, damage to the immune system and so-called chloracne: skin changes, lumps, abscesses and cysts. Physical and mental development can also be delayed by PCBs. In Japan and Taiwan in the late 1960s and 1970s, there was mass human poisoning from rice oil contaminated with PCBs, resulting in stillbirths and deformities.
Accumulation of PCBs in the marine food chain
|PCB leads to liver, spleen and kidney damage, is carcinogenic and affects the sex hormone balance|
Use of PCB
PCB was used in many ways. It was used as a lubricant or in hydraulic fluids, as a plasticizer in paints and plastics (sometimes up to 50% of the weight!), In joint sealing compounds of all kinds, e.g. for permanently elastic expansion joints in concrete construction, connection joints for doors, windows, sanitary etc. PCB was used for many insulating materials. In the past, PCB-containing insulating oils were used in the manufacture of capacitors. Such PCB loaded capacitors are present in many older technical devices. (The designations MP, MKP, MPK on capacitors indicate that they are PCB-free). PCB was also used as a flame retardant in paints and varnishes, had a positive acoustic effect in wall and acoustic ceiling tile paints (white color) and PCB was also used as an adhesive for floors.
Examples of PCB uses:
Ballast of fluorescent lamps
Joint sealing compounds
Paint and varnishes
Hazard identification and assessments
In the outside air of buildings with PCB sources, concentrations of up to 10 ng / m3 air occur. Indoors up to 1,000 ng / m3 and in individual cases even up to 10,000 ng / m3. Research showed that PCB contaminated materials that were used indoors before the 1972 ban, e.g. T. still today lead to pollution of the indoor air. Countless questions remain unanswered about the long-term effects on humans caused by low levels of PCBs. Improper renovations are strongly discouraged. The risk of uncontrolled release is great. It can happen that the indoor pollution is significantly higher after improper disposal than before the renovation.
The use of PCBs in open systems (e.g. joint sealants, paints and varnishes) was banned in Switzerland in 1972. A general ban has been in place since 1986. A legally prescribed limit value for substances containing PCBs of 50 ppm (mg / kg) applies to remediation. Reclaimed PCB waste must be disposed of as hazardous waste in airtight containers. The provisions of the Ordinance on the Movement of Waste (VeVA) also apply.
Download: "Fact sheet PCB"
Download: "Graphic PCB in the marine food chain"
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