PCB - polychlorinated biphenyls
Even though PCBs were prohibited in new use in Norway from 1980, we can still find them in several products that are in use today.
PCBs are a group of organic pollutants consisting of two benzene rings with 1-10 chlorine atoms in different positions around these rings. There are 209 theoretical combinations called congeners. However, usually only a selected number of congeners are reported in environmental studies. NGU uses 7 congeners called the Seven Dutch (IUPAC no. 28, 52, 101, 118, 138, 153, and 180) in all studies.
PCBs were produced mainly between 1930 and 1975. Selected properties of these substances include thermic, chemical and physical stability in addition to their ability to function as fire retardants and plasticizers. For these reasons, PCBs were added to hydraulic oils, electrical installations, and paint/sealants.
Even though PCBs were prohibited in new use in Norway from 1980, we can still find them in several products that are in use today. PCBs are persistent in nature (i.e., non-degradable), which means that we can find them in samples of soil, air, water and biological material all over the world. Since PCBs are hydrophobic, they are able to bioaccumulate and biomagnify in organisms and food chains. Of the toxicological effects, PCBs have been proven to cause impaired immune defense, disturbance of the hormone balance, in addition to infertility. PCBs have also been proven to cause cancer.
NGU has studied PCBs in soil, urban runoff, building materials, and precipitation for several years., The results indicate that in Norway the PCB-challenge is somewhat larger in Bergen compared with other Norwegian cities such as Oslo, Trondheim, Harstad, and Tromsø, even though the concentrations seem to vary locally. The highest concentrations of PCBs in soil are generally found in urban areas. NGU has carried out studies of PCBs in soil and other materials in the settlements on Svalbard. The PCB-concentrations found in Barentsburg and Pyramiden are much higher compared with cities onmainland Norway. The Svalbard studies focus on local PCB sources such as paint, discarded electrical installations, and repair-shop activities.
Dioxins and furans
The compounds are spread through smoke into the atmosphere where weather and wind regulate how far and wide the compounds are spread. Dioxins and furans are toxic compounds that consist of benzene ringswhich degrade very slowly in soil. A varied amount of chlorine atoms are bound to the benzene rings, which gives rise to different dioxin and furan compounds with a varying degree of toxicity.
The compounds are primarily created through incineration of organic waste, where the presence of chlorine and lack of oxygen increase the production rate. The compounds are normally created within a temperature range of 300 to 500 degrees Celsius. At higher temperatures the compounds start to destruct.
The compounds are spread through smoke into the atmosphere where weather and wind regulate how far and wide the compounds are spread.
Usual sources in an urban environment include:
- Incineration plants
- Domestic and industrial wood burning
- Metal industry
- Traffic
- Urban fires
- Crematoria
- Diffuse sources
NGU has conducted a study of dioxins and furans in surface soil samples from Trondheim.
There appears to be a strong correlation between the concentration levels of dioxins in soil and the age of habitation in the different parts of town.
PAH
Polycyclic aromatic hydrocarbons (PAH) are organic compounds which are common in tar that has been used for centuries to preserve wooden material in buildings and ships. Several of these compounds are carcinogenic in low concentrations (e.g. benzo(a)pyrene).
Formation of PAH can also take place by combustion and during fires. PAH are present in fossil fuels such as oil and coal. The spreading of PAH to soil is an important process in inner urban areas where human activity has taken place during centuries.
NGU has mapped the occurrence of PAH in soil in several Norwegian cities, major heavy industrial centres and pristine areas with natural background levels in soil. NGU has a chemical database for soil with more than 7,000 PAH sample data.
Phthalates
Phthalates are organic compounds used in large quantities as plasticizers. Phthalates may be released into the environment from industrial processes, addition to products, use, disposal and recycling of products. The presence of phthalates has been documented in many parts of the ecosystem - including food.
Phthalates accumulate to various extents in organisms and disintegrate at a slower rate in sediments than in water. The most common phthalate compound is diethyl phthalate (DEHP). The global annual product use of DEHP is almost 1.8 million tonnes.
In Norway, the annual release to the aqueous environment is estimated to be 1,5 tonnes based on concentrations measured in public sewage systems.
NGU has studied the presence of phthalates in surface soils in daycares in Oslo, while other projects are currentlyat the planning stage.
Brominated flame retardants
Brominated flame retardants are emitted into air, water and soil from several processes.Brominated flame retardants consists of a group of organic compounds that contain the element bromine, which is a flame retarding agent. The Norwegian environmental protection authorities prioritise a few compounds, among these the polybrominated diphenylethers (PBDE).
Brominated flame retardants are emitted into air, water and soil from several processes: from industrial production, from product use, from recycling, and from waste management.
NGU has recently had 50 surface-soil samples analysed for 17 PBDE compounds, in a project in collaboration with the Environmental Protection Agency (EPA) and Trondheim municipality.. A survey of this extent has not been done previously in Norway. PBDE can be seen in all samples, which documents an active spreading of PBDE from different sources to soil.
No spatial extent pattern can be seen as samples with relatively high concentrations are spread all over the city.