Aquatic Toxicity of Mixtures. Technical Report No. 80

The inherent toxicity of a substance to aquatic organisms is typically determined via single species laboratory tests. Results from these tests are used to determine a Predicted No Effect Concentration (PNEC) for ecosystems per substance. Since organisms in the environment are exposed simultaneously to a wide array of substances, it is important to understand the potential effects of mixtures to aquatic organisms. The effects of mixtures can be generally categorised as additive, greater than additive (synergism) and less than additive (antagonism). Effects that correspond to the addition of toxicities for each mixture component are considered additive.