ECOTOXICOLOGICAL RISK-EVALUATION OF THE CATIONIC FABRIC SOFTENER DTDMAC .3. RISK ASSESSMENT

The use of cationic surfactants in the Netherlands (about 2500 tonnes as active ingredient on an annual basis) poses a serious risk to a wide variety of aquatic ecosystems. On the basis of ecotoxicological studies with ditallow-dimethyl-ammoniumchloride (DTDMAC), the most important fabric softener, a maximum permissible risk level of 50-mu-g/l and a negligible risk level of 0.5-mu-g/l have been derived. In 1990, concentrations of 6 - 25-mu-g/l were measured in the rivers Rhine, Meuse and Scheldt. Model predictions, confirmed by measurements in Germany and The Netherlands, show that in approximately 30 to 40% of the surface waters considerably higher DTDMAC are expected to occur. On the basis of this risk evaluation, which was discussed in the Dutch Parliament in spring 1990, the Netherlands Association of Detergent Industries agreed to replace DTDMAC by chemicals of lower environmental concern within a period of two years. Already by the end of 1990 almost all DTDMAC had been replaced by readily biodegradable substitutes. However, in June 1991, DTDMAC was detected in the rivers Rhine, Meuse and Scheldt at concentrations between 12 and 34-mu-g/l, which indicates that other than only national measures are required to reduce the large-scale pollution of surface waters with DTDMAC.