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1,2-dichlorobenzene

Report

To read the report please click here.

This marine risk assessment was also published in a peer-reviewed journal: Van Wijk, D. et al., 2004. 1,2-Dichlorobenzene Marine Risk Assessment with Special Reference to the OSPARCOM region: North Sea. Environmental Monitoring and Assessment, Vol. 97, (1-3), 87-102.

Summary

Current usage of 1,2-dichlorobenzene does not represent a risk to the marine environment. This conclusion is based on 67 laboratory toxicity studies, plus 1983-1995 monitoring results from the North Sea, rivers and estuaries.

Applications of 1,2-dichlorobenzene

In 1988, some 21,000 tonnes of 1,2-dichlorobenzene were produced in Western Europe, with utilisation estimated at about 24,000 tonnes.

Western European manufacturers of the compound are Bayer AG (Germany), Elf Atochem SA (France) and EniChem (Italy).

Worldwide production of 1,2-dichlorobenzene totalled some 55,000 tonnes in 1988.

The compound is used as a basic material in product synthesis. It is converted into intermediate and end products in closed systems. In 1991, Western European use of 1,2-dichlorobenzene totalled 24,000 tonnes, of which 87.5% in production of 3,4-dichloronitrobenzene, 2.5% as a TDI process solvent, 1.7% as a solvent for other processes and 8.3% for other uses. The primary routes by which it enters the environment during manufacture, processing and usage are via water and air. In 1995, emissions to water totalled 14.4 tonnes, and to air, 20.5 tonnes, based on a survey of 76 European sites.

Indirect entry of 1,2-dichlorobenzene into the environment is possible during

• dumping of sewage sludge in the North Sea or disposal in soil
• metabolic breakdown of lindane
• biotic and abiotic degradation of more highly chlorinated benzenes.

These indirect routes of entry are not quantifiable but are assumed to be relatively minor.

Evaluation of environmental risk

Toxicity

For 1,2-dichlorobenzene, 26 data for fish, 24 data for invertebrates and 17 data for algae were evaluated according to the environmental quality criteria recommended by EU authorities. Both acute and chronic toxicity studies were taken into account and the appropriate assessment factors were used to define a final PNEC value of 37 µg/l.

Monitoring data

All the monitoring data available indicate a typical concentration in estuaries lower than 0.1 µg/l. The concentration measured in Dutch coastal waters was 0.019 µg/l. Typical recent concentration values in rivers are lower than 0.3 µg/l.

Available data on persistence of 1,2-dichlorobenzene indicate a half-life in water of a few hours or days, and significant biodegradation potential and only a slight bioaccumulation potential in marine organisms. Current use of 1,2-dichlorobenzene does not therefore represent a risk to the aquatic environment.

Risk assessment conclusion

The calculated PEC/PNEC ratio gives a safety margin of 100 to 300 between the predicted no effect concentration and the exposure concentration. Dilution within the sea would increase those safety margins.

North Sea monitoring data on 1,2-dichlorobenzene