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MonochlorobenzeneReportTo read the report please click here. This marine risk assessment was also published in a peer-reviewed journal: Van Wijk, D. et al., 2004. Monochlorobenzene Marine Risk Assessment with Special Reference to the OSPARCOM region: North Sea. Environmental Monitoring and Assessment, Vol. 97, (1-3), 69-86. SummaryCurrent usage of monochlorobenzene does not represent a risk to the marine environment. This conclusion is based on 64 laboratory toxicity studies, plus 1990-1995 river monitoring results. Applications of monochlorobenzeneSome 70,000 tonnes of monochlorobenzene were produced in Western Europe in 1993, and imports amounted to 10,000 tonnes. Total consumption was 80,000 tonnes. Worldwide monochlorobenzene production in 1993 was about 365,000 tonnes. Monochlorobenzene is manufactured in Western Europe by Bayer AG (Germany), Elf Atochem and Rhodia (France) and EniChem (Italy). It is a basic substance used in chemical syntheses. Some 95% of the volume used is converted in closed systems to intermediate and final products. In 1987, it was estimated that Western European monochlorobenzene consumption of 97,000 tonnes was divided as follows: 77% was used to manufacture nitrochlorobenzenes; 16% for other chemical transformations (such as production of diphenyl oxide and diphenyldichlorosilane); 5% for process solvents (to produce isocyanates); and 2% for solvents in general (for example, as part of formulated crop protection products, or in dyes). The main routes by which monochlorobenzene enters the environment during manufacture, processing and usage are to water and air. Emissions from 78 European sites were estimated at 6.6 tonnes to water and 45.8 tonnes to air in 1995. These values represent a 70-85% reduction against 1985. Monochlorobenzene primarily enters the soil via crop protection agents. The quantities used for this application have fallen in recent years. It then enters water by leaching and air by evaporation. Monochlorobenzene can also enter the environment during incineration of household waste and special waste and through biotic and abiotic degradation of more highly-chlorinated benzenes. Evaluation of environmental riskToxicity For monochlorobenzene, 27 data for fish, 24 data for invertebrates and 13 data for algae were evaluated using 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 32 µg/l. Monitoring data Recent monitoring data indicate that the concentration of monochlorobenzene in surface waters is below the determination limit of 0.1, 0.2, 0.5 µg/l used in monitoring programmes such as that on the Rhine. Using half of the lowest determination (0.1 µg/l) as a typical case assumption a PEC of 0.05 µg/l was derived. A worst case of 0.5 µg/l is assumed. Data for 1990-95 came from the Rhine (Germany); the Meuse/Rhine (Netherlands); the Seine (France); and the Tees (UK). Available data on persistence of monochlorobenzene indicate a half-life in water of a few hours or days, a significant biodegradation potential and no significant bioaccumulation potential in marine organisms. Current use of monochlorobenzene does not therefore represent a risk to the aquatic environment. Risk assessment conclusionThe calculated PEC/PNEC ratios give a safety margin of 60 to over 500 between the predicted no effect concentration and the exposure concentration. Dilution within the sea would increase these safety margins.
North Sea monitoring data on monochlorobenzene |