Polychlorinated biphenyls

PCB; formula: C12H10-xClx
General structure of polychlorinated biphenyl
Source: Wikipedia

Persistent and toxic chlorinated compounds

Polychlorinated biphenyls are a class of 209 chlorinated hydrocarbons which share a common biphenyl structure but vary in number and position of chlorine atoms (congeners). The identification of the single congeners is facilitated by numbers whereby higher numbers are normally associated with a higher degree of chlorination. The degree of chlorination determines the physico-chemical properties of the compound, e.g. with increasing degree of chlorination, viscosity and lipophilicity increase but vapour pressure and water solubility decrease.

Commercial products always contain mixtures of 50-70 different congeners. Depending on the degree of chlorination they are thin or viscous oils.
Until the 1980s PCBs were widely used, e.g. as hydraulic fluids, lubricating oils, cooling and insulating fluids in transformers and capacitors, plasticisers and flame retardants in paints, plastics, sealing compounds and insulates.

Due to their wide application and high persistence, PCBs are ubiquitous. In the atmosphere they can be transported over long distances.
PCBs are accumulated by organisms and enriched in the food web (biomagnification). Furthermore, they are of high chronic toxicity and are suspected to be carcinogenic, teratogenic, reproductive toxic and developmental toxic and to act as endocrine disruptors.

Since 1983, PCB production is banned in the Federal Republic of Germany. When the Stockholm Convention entered into force in 2004, PCBs were banned worldwide.

For practicability reasons, analysis of PCB in samples is mostly restricted to six so called indicator-congeners (PCB-28, -52, -101, -138, -153, -180). These were chosen according to toxicological aspects.
Furthermore, PCB-118 is often analysed as representative of the dioxin-like PCBs.

Substances

PCB101 PCB101 is a low chlorinated, relatively volatile PCB. Together with other low chlorinated congeners (e.g. PCB28 and 52) it stands for acute contamination of the ambient air. It degrades rather fast and accumulation in organisms is lower compared to higher chlorinated congeners.
PCB118 PCB118 belongs to the toxicologically relevant group of dioxin-like PCBs (also known as WHO-PCBs) that have molecular-biological properties resembling those of dioxins and furans. They are highly toxic. Technical mixtures of PCB contain only trace amounts of dioxin-like PCB. They can occur as by-products of incineration processes.
PCB138 PCB138 is a higher chlorinated PCB. It is hardly degradable and accumulates strongly in organisms and the food web. Together with other high chlorinated congeners (e.g. PCB153 and 180) it stands for long-term contamination mainly through food.
PCB153 PCB153 is a higher chlorinated PCB. It is hardly degradable and accumulates strongly in organisms and the food web. Together with other high chlorinated congeners (e.g. PCB138 and 180) it stands for long-term contamination mainly through food.
PCB180 PCB180 is a higher chlorinated PCB. It is hardly degradable and accumulates strongly in organisms and the food web. Together with other high chlorinated congeners (e.g. PCB138 and 153) it stands for long-term contamination mainly through food.

Specimen

Zebra mussel Common mussel species as invasive animal in rivers and lakes with high information level for water pollution
Bream Bioindicator in rivers and lakes
Suspended particulate matter Fine insoluble mineral or organic particles in the water phase
Blue mussel One of the most important edible mussel species common in the North and Baltic Sea
Eelpout As the only viviparous fish in German nearshore waters, it is a bioindicator in nearshore coastal marine ecosystems.
Herring gull Inshore, the herring gull mainly feeds from the sea: upon fish, mussels, and crabs.
Common spruce A major primary producer in semi-natural and anthropogenic affected ecosystems.
Pine A major primary producer in semi-natural and anthropogenic affected ecosystems.
Roe deer, one-year-old The roe deer is the most common of the larger herbivores (first order-consumer) to be found in the wild in Europe.
Feral pigeon A pigeon species home in nearly every city.
Earthworm (Aporrectodea longa) As an organism living at ground level, it is a major driver of the decomposition of organic material (e.g. plant litter).
Earthworm (Lumbricus terrestris) As an organism living at ground level, it is a major driver of the decomposition of organic material (e.g. plant litter).
Soil Soil is livelihood and biosphere for humans, animals, plants and soil organisms. All the substances brought in are transported, transformed and/or accumulated in the soil.
Students Student groups with an even number of female and male students at the age of 20 to 29.

Sampling area

BR/NP Berchtesgaden The only high mountains national park in Germany and an area of the Limestone Alps with international relevance
Saarländischer Verdichtungsraum Important, old-industrialised conurbation in Germany.
Bornhöveder Seengebiet Main water divide between the North- and Baltic Sea
Rhein Longest river in Germany
NP Bayerischer Wald Germany's first national park
NP Vorpommersche Boddenlandschaft National Park in the largest brackish water (Bodden) habitat of the world.
BR/NP Wattenmeere National park in the world largest connected sand and mud flats.
Elbe Fourth largest river basin in Central Europe
Verdichtungsraum Halle-Leipzig Region in the chemical triangle of Central Germany
NP Harz Germany's largest forest national park
Solling Second highest and largest low mountain range in Northern Germany
BR Pfälzerwald Germany's largest connected forest area in a range of low mountains
Oberbayerisches Tertiärhügelland The Upper Bavarian Tertiary Uplands are a part of the Southern German Molasse Basin
Donau Second largest river in Europe
Sampling sites (humans) 4 university cities as sampling areas.

Sampling period

1985 - 2018