Analysis of the ecetoc aquatic toxicity (EAT) database IV — Comparative toxicity of chemical substances to freshwater versus saltwater organisms

In contrast to the substantial quantity of information available on the ecotoxicity of chemical substances to freshwater organisms, there are relatively few data on the effects of many such substances to marine and estuarine organisms. While it is desirable to improve the ecotoxicity database for saltwater (viz. estuarine and marine) species, there is an immediate need to conduct risk assessments for those substances which may enter the marine environment, and in some cases, this requires the extrapolation of freshwater ecotoxicity data to saltwater species. In order to examine the rationale for this extrapolation, a comparison has been made of the sensitivities of related freshwater and saltwater fish and invertebrates to various substances, based on the ECETOC Aquatic Toxicity (EAT) database. In summary: (1) for fish, freshwater and saltwater species were within a factor of 10 in their sensitivity to 91% and 93% of all substances (based on EC50 and NOEC values, respectively); (2) for invertebrates, freshwater and saltwater species were within a factor of 10 in their sensitivity to 33% and 83% of all substances (based on EC50 and NOEC values, respectively). Given the limited number of data available, the preliminary nature of these conclusions is emphasised. Insufficient data were available to allow a similar comparison between freshwater and saltwater plants and algae. There is a need for more high quality data on the effects of a wide range of chemical substances to both freshwater and saltwater organisms, and especially algae and plant species.