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Trichloroethylene

Report

To read the report please click here.

This marine risk assessment was also published in a peer-reviewed journal: Boutonnet, J-C. et al., 1998. Euro Chlor risk assessment for the marine environment Osparcom region: North Sea – Trichloroethylene. Environmental Monitoring and Assessment, Vol. 53, (3), 467-487.

Summary

Current usage of trichloroethylene does not represent a risk to the marine environment in the North Sea. This conclusion is based on 63 aquatic toxicity studies, plus 1991-95 North Sea analytical monitoring results.

Applications of trichloroethylene

In 1995, consumption of trichloroethylene in the EU was about 110,000 tonnes, including 10,000 tonnes imported from the US or Eastern Europe. EU exports of trichloroethylene total about 20,000 tonnes per year.

More than 80% of trichloroethylene is used for vapour degreasing and cleaning of metal parts. Introduction of more efficient and closed degreasing equipment over the past decade has lowered workplace and environmental emissions and, as a result, trichloroethylene consumption. In vapour degreasing systems, it is used as a replacement for 1,1,1-trichloroethane (phased out in the developed world under the Montreal Protocol in 1995). Trichloroethylene is also used in adhesives, for synthesis in the chemical industry (about 20,000 tonnes is used as a feedstock for the CFC substitutes, HCFCs and HFCs), and as a solvent for various products. In solvent applications, it is recycled extensively.

Trichloroethylene is mainly produced jointly with tetrachloroethylene (also called perchloroethylene), by the so-called "tri/per" process. This is based on chlorination or oxychlorination of various raw materials. The major raw material is currently the light fractions of residues from vinyl chloride monomer (VCM) manufacture.

Evaluation of environmental risk

For trichloroethylene, the evaluation of toxicity was based on 14 sets of data for algae, 30 for invertebrates and 9 for fish in both marine and freshwater media. These were assessed using the environmental quality criteria recommended by the European authorities.

Both acute and chronic toxicity studies were taken into account, and the appropriate assessment factors were used to define a final Predicted No-Effect Concentration (PNEC) value of 150 µg/litre.

Monitoring measurements were taken in Germany (Weser estuary), the Netherlands (Rhine and Maas estuary), the German/Dutch border (Rhine), the Belgian/ Dutch border (Maas, Schelde, Meuse), the UK (river estuaries) and France (Seine estuary).

The most recent data (1991-95) support a typical PEC of 0.1 µg trichloroethylene/l water and a worst case PEC of 3.5 µg/l water. Data on persistence of trichloroethylene indicate a half-life in water of a few hours or days, and negligible bioaccumulation in aquatic organisms. It is not a substance which should be considered as being persistent, toxic and liable to bioaccumulate (PTB) in the environment.

Risk assessment conclusion

When the environmental concentration of trichloroethylene in rivers and coastal waters/estuaries is compared with the predicted no-effect level to give the PEC/PNEC ratio, there is a safety margin of 40-1500 between actual exposure and the level at which no effect on the environment would be expected. This calculation takes no account of any further dilution within the sea, which would increase these safety margins.

Current use of trichloroethylene does not, therefore, represent a risk to the marine environment.

This evaluation was done as a parallel exercise with the continuing European Risk Assessment, the scope of which is broader and covers all compartments.

Risk assessment conclusion for Trichloroethylene

North Sea monitoring data on Trichloroethylene