Aquatic ecotoxicity is required with biodegradation and bioaccumulation in EU Legislation, in order to assess the potential hazard of chemicals, and their subsequent classification as Dangerous for the Environment (R50 label). Also, this aspect is needed for Aquatic Risk determinations: the Maximum Permissible Concentration is an important parameter for those determinations, and is the highest concentration of a given substance at which no effects on the species living in the environmental compartment studied are observed.

For classification purposes, acute ecotoxicity for algae, invertebrate and fish have to be established. Acute ecotoxicity tests use relatively high concentrations of test substance and short periods of time, so the main observed effect is mortality.

The aquatic toxicity of LAS has been extensively studied and several comprehensive reviews have been prepared. The data cover a wide range of taxonomic groups and the resulting data exhibit a relatively large degree of intra- and inter- species variability. This variability is due to differences in test design, differences in species sensitivity, and the use of different individual compounds and mixtures of LAS. As toxicity depends on these characteristics of chemical structure, all these data are not comparable. This means that toxicity data have to be normalised to an specified alkyl chain length.
Table 1 summarises acute toxicity data for commercial LAS, namely products with C10-C13 alkylchains, and with average carbon atoms near C11.6.

This data have been selected from the HERA-LAS Report (Human and Environmental Risk Assessment for LAS), a voluntary initiative from the European formulators and manufacturers of household cleaning products, as well as suppliers and manufacturers of the raw materials (www.heraproject.com).

LAS toxicity values are so far from the limits established by the European Legislation and thus, it is not classified as Dangerous for the Environment. For Risk Assessment purposes, tests based on real world conditions confirm that LAS is safe for aquatic populations (see "Behaviour of LAS" for more information).