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1,4-dichlorobenzene

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., 2004. 1,4-Dichlorobenzene Marine Risk Assessment with Special Reference to the OSPARCOM region: North Sea. Environmental Monitoring and Assessment, Vol. 97, (1-3), 103-117.

Summary

Current usage of 1,4-dichlorobenzene does not represent a risk to the marine environment. This conclusion is based on 33 laboratory toxicity studies, plus 1989-1995 monitoring results from the North Sea, rivers and estuaries.

Applications of 1,4-dichlorobenzene

1,4-dichlorobenzene is produced by chlorination of benzene in the presence of a catalyst. 1,2-dichlorobenzene is a co-product. Crystallisation and distillation are used to separate the isomers. 1,4-dichlorobenzene is produced in Europe by Bayer AG (Germany), Elf Atochem (France) and EniChem (Italy). Total EU production was estimated at 25,500 tonnes in 1994, with exports totalling some 14,800 tonnes and imports around 10,000 tonnes. However, EU experts estimated up to 15,000 tonnes/year of European consumption.

1,4-dichlorobenzene is used mainly in three applications:

• 50% is used as raw material in synthesis of pesticides, resins, and dyestuffs
• 22% is used as a deodorant in toilet blocks
• 28% is used as moth repellent

1,4-dichlorobenzene mainly enters the water and air from its use as a deodorant in toilet blocks and as a moth repellent. Total water and air emissions in the EU were estimated based on a total consumption of 15,000 tonnes/year as 427 and 7,258 tonnes/year for both production and uses. About 98% of these emissions is coming from the general public use of the substance.

Evaluation of environmental risk

Toxicity

For 1,4-dichlorobenzene, 17 data for fish, 9 data for invertebrates and 7 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 20 µg/l.

Monitoring data

Recent monitoring data available indicate that the concentration in coastal waters and estuaries is below the determination limit of 0.1 µg/l used in the monitoring programs. A worst case value in river water was found to be lower than 0.45 µg/l. Data came from various rivers including the Rhine and Elbe (Germany, 1990-93); the Rhine and Meuse (Netherlands, 1990); and the Seine (France, 1995).

Available data on persistence of 1,4-dichlorobenzene indicate a good biodegradation potential and no significant bioaccumulation potential in marine organisms. Current use of 1,4-dichlorobenzene does not therefore represent a risk to the aquatic environment.

Risk assessment conclusion

The calculated PEC/PNEC ratio give a safety margin of about 40 to 200 between the predicted no effect concentration and the exposure concentration. Dilution within the sea would increase these safety margins.

North Sea monitoring data on 1,4-dichlorobenzene