Properties and Uses

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Polychlorinated biphenyls are odourless, tasteless, chemicals ranging in appearance from colourless, oily liquids to more viscous and unreasoningly darker yellow liquids, to yellow and black resins. Colour and viscosity are dependent on chlorine content.

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PCBs are very stable compounds and do not decompose readily or degrade significantly by chemical, thermal, and biochemical processes.

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PCBs were used as coolants and insulating fluids for transformers and capacitors especially in components of early fluorescent light fittings and electrical transformers. They were also used as plasticisers in paints and cements, stabilising additives in flexible PVC coatings of electrical wiring and electronic components, in pesticide extenders, cutting oils, reactive flame retardants, lubricating oils, hydraulic fluids, sealants, adhesives, wood floor finishes, water-proofing compounds, casting agents, vacuum pump fluids, fixatives in microscopy, surgical implants and carbonless copy paper.

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Health Effects

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The most commonly observed health effects in humans exposed to extremely high levels of PCBs are skin conditions such as chloracne and rashes. Studies in workers exposed to PCBs have shown changes in blood and urine that may indicate liver damage. Common symptoms include dermal and ocular lesions, irregular menstrual cycles and a lowered immune response. Other symptoms included fatigue, headache, cough, and unusual skin sores. Additionally, PCB exposure in children can lead to poor cognitive development.

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Animals that eat PCB-contaminated food even for short periods of time suffer liver damage and may die. Animals that ingest smaller amounts of PCBs in food over several weeks or months develop various health effects, including anaemia, acne-like skin conditions (chloracne), and liver, stomach, and thyroid gland injuries. Other effects of PCBs in animals include changes in the immune system, behavioural alterations and impaired reproduction. PCBs are not known to cause birth defects in humans, although those that have dioxin-like activity are known to cause a variety of teratogenic effects in animals.

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Studies have shown that PCBs alter estrogen levels in the body and contribute to reproduction problems. In vitro endocrine disruption can occur due to exposure to PCBs. Chemical causing endocrine disruption can pose a serious threat to reproduction in top-level predators.

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PCBs readily penetrate skin, PVC (polyvinyl chloride), and latex (natural rubber). PCB-resistant materials include Viton, polyethylene, polyvinyl acetate (PVA), polytetrafluoroethylene (PTFE), butyl rubber, nitrile rubber, and Neoprene.