English Abstract This pilot study presents data on the acute toxicity of
26 chemicals for 196 aquatic species. For some chemicals there is a large
variability in sensitivity between species, up to factors of 10,000 or more.
Statistical analysis showed that differences in sensitivity are clearly
related to the taxonomic classification of the species at the level of the
class. Relationships at lower levels of the taxonomic classification could
not be investigated due to the limited number of data from different orders,
families and genera. The study will be continued by extending the data set
and adding information on the mode of action of the chemicals and on
biological attributes that might explain the variability in sensitivity
between species. Future analyses will aim at the construction of
Quantitative Species Sensitivity Relationships.