This International Standard describes a method for the determination of the acute toxicity to one of three specified species of marine copepod (Copepoda, Crustacea) of a) chemical substances which are soluble, or can be maintained as a stable suspension or dispersion, under the conditions of the test; b) industrial or sewage effluents, treated or untreated, after decantation, filtration or centrifugation if necessary; c) marine or estuarine waters.