This International Standard specifes a method for the determination of the acute toxicity to Daphnia magna Straus (Cladocera, Crustacea).This method is applicable to:- chemical substances which are soluble under the conditions of the test, or can be maintained as a stable suspension or dispersion under the conditions of the test;- industrial or sewage effuents;- treated or untreated waste water;- aqueous extracts and leachates;- fresh water (surface and ground water);- eluates of fresh water sediment;- pore water of fresh water sediment.