Eawag News 64e: The MolDarT – a new toxicity test

More than 100,000 commercially used chemical compounds are currently registered in the European Union [1]. Under the new EU REACH legislation (Registration, Evaluation and Authorisa‐ tion of Chemicals [2]), which came into effect in June 2007, existing chemicals and all new substances, starting materials and intermediates exceeding an annual production volume of 1 tonne have to be tested for toxic effects. These requirements cover an estimated 30,000 substances. For toxicity studies, the Organisa‐ tion for Economic Co‐operation and Development (OECD) recom‐ mends the use of appropriate model organisms and a series of tests for the assessment of acute and chronic toxic effects. These involve the exposure of adult fish to contaminants in water for periods of 96 hours (acute) or at least 14 days (chronic toxicity). The toxicological criterion applied is lethality – a non‐specific, integrative endpoint, which depends on the concentration and toxicity of the compounds tested. In vivo tests of this kind are