PCB, the polychlorinated biphenyls, are a group of 209 synthetic, chlorinated hydrocarbons. They are thermally stable, chemically inert and plasticising, and precisely these properties made them a sought-after additive in joint sealants, seals and coatings. The same properties are today the problem: PCB practically do not break down in the environment. They are found worldwide, from Arctic ice to the deep sea, and in the building they sit where they were installed decades ago, and continue to off-gas.
In Austria, PCB-containing joint sealants were installed from about 1955 to the end of the 1970s, especially in precast-concrete buildings, office buildings and schools. PCB has been banned in Austria since 1993. The joints from that time are often still there.
Where PCB occurs in buildings
- Building joints: elastic sealing compounds between precast concrete elements, on facades, between floor slabs and external walls. The most common source.
- Window joints: sealing compounds around window frames, especially in metal windows of the 1960s and 1970s.
- Expansion joints: in floors, car parks and industrial buildings.
- Coatings and paints: rarer, but possible, for example in corrosion-protection paints.
The joint sealants are usually grey, beige or black and become hard and cracked over time.
Why PCB are dangerous
PCB off-gas continuously from the joint sealant into the room air over decades and accumulate in house dust. In the body they are fat-soluble, deposit in the fatty tissue and are broken down only very slowly. The IARC of the WHO classifies PCB as carcinogenic to humans (Group 1), and the dioxin-like PCB likewise. Alongside this, liver damage, a weakening of the immune system and disruptions of the hormone system are described. Children and pregnant women are considered particularly sensitive.
Why the source is not only the joint
One peculiarity makes PCB in the building treacherous. From the joint sealant, the primary source, the compounds migrate over years into adjacent, porous components, into concrete, plaster and screed. These components thereby become secondary sources that continue to off-gas even when the original joint has long been removed. A PCB remediation is therefore rarely done with cutting out the joint; often the contaminated surroundings must be assessed as well.
How to determine PCB
At the start there is a material sample of the suspect joint sealant, a small piece of a few centimetres, examined in an accredited laboratory. Recorded are the six indicator congeners (PCB 28, 52, 101, 138, 153 and 180), from which the total content is extrapolated. If joints are extensively exposed or there are complaints, a room-air measurement completes the picture. Sampling on one's own is not advisable, and extensively exposed joints should not be worked on by oneself; this belongs in expert hands.
The legal framework
PCB has been banned in Austria since 1993 (Ordinance on the prohibition of halogenated biphenyls, terphenyls, naphthalenes and diphenylmethanes, BGBl. No. 210/1993). EU-wide and internationally PCB are recorded as persistent organic pollutants under the Stockholm Convention. PCB-containing building materials are hazardous waste and must be disposed of accordingly. Austria has no binding limit of its own for PCB in indoor air; as orientation the German guide values of the Committee on Indoor Air Guide Values (AIR) serve, lowered considerably in 2025: a precautionary value (guide value I) of 80 ng/m³ and a hazard value (guide value II) of 800 ng/m³, related to the sum of PCB. Below the precautionary value the exposure is considered tolerable in the long term; above it the source is to be sought and the concentration reduced, and from the hazard value there is a need for action.
What to do
- PCB joints intact, no room-air burden: document and have professionally removed at the next renovation.
- Joints exposed, cracked or extensive in indoor spaces: room-air measurement advisable. Above the precautionary value: identify the source, reduce the concentration, professionally remediate the joints.
- Renovation planned: PCB joint sealants and contaminated neighbouring components belong in the hands of a specialist firm, with protective measures, and the waste is to be disposed of as hazardous waste.
PCB rarely occurs alone. In buildings of the 1960s to 1980s there is often also asbestos and old mineral wool insulation (MMF).
Sources
- IARC/WHO, Monograph 107 (2013): PCB and dioxin-like PCB as Group 1 carcinogens
- Prohibition of halogenated biphenyls, terphenyls, naphthalenes and diphenylmethanes, BGBl. No. 210/1993, RIS: ris.bka.gv.at
- Committee on Indoor Air Guide Values (AIR), „Richtwerte für PCB in der Innenraumluft", Bundesgesundheitsblatt, Vol. 68, No. 2 (2025) (guide value I 80 ng/m³, guide value II 800 ng/m³)
- Environment Agency Austria, „Polychlorierte Biphenyle (PCB)": umweltbundesamt.at
- arguk.de, „PCB im Innenraum: Vorkommen und gesundheitliche Bedeutung" (primary and secondary sources)
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