TR 091 – Aquatic Hazard Assessment II


TR 091 : Aquatic Hazard Assessment II | November 2003

The ECETOC Aquatic Toxicity (EAT) database (ECETOC, 1993) has been updated, mainly from data published between 1992 and 2000, to include information on the toxicity of substances to aquatic species in fresh and saline waters. The principal quality criteria for acceptance of data were that test methods should be well described and the toxicant concentrations must be measured. On this basis, 178 (33%) of the 537 papers examined were found to be suitable for inclusion in the new database, and 359 publications were rejected. The new database (EAT 3), which contains more than 5450 entries on almost 600 chemicals, provides the most comprehensive compilation of highly reliable ecotoxicity data published in the scientific press in the period 1970 – 2000.

The EAT 3 database is available as an Excel spreadsheet. For each entry there are 32 fields of information on the substance, test species, test conditions, test description, endpoint, results and source references. All the references are held at ECETOC.

An additional database consisting of ecotoxicity data from ‘test kits’ such as Microtox has been prepared and is available as a stand-alone database (EAT 4) or combined with EAT 3 (EAT 5).

Some examples of the use of the EAT 3 database are provided in this report, including comparisons between species, environments, acute and chronic exposures and different life stages.

With careful consideration of the particular ecosystem for which protection is required, typical ‘standard’ species can be used as effective surrogates for other species within their larger taxonomic grouping (fish, invertebrate, algae). There seems to be a good possibility of replacing fish tests with tests using invertebrates, algae and tissue cultures. While this may prove satisfactory for the needs of the ‘registration and evaluation’ steps in the emerging White Paper on the Strategy for a Future Chemicals Policy in Europe (EC, 2001), the more ecological approach in the future application of the Water Framework Directive (EC, 2000) may require a reassessment of these conclusions.

Broad equivalence of sensitivity to narcotic chemicals has been demonstrated for higher taxa represented in both fresh and salt water environments. However, the marine environment contains many aquatic taxa that are not represented in freshwater. Given the greater diversity of species present in salt waters relative to freshwaters, there are uncertainties over whether the current approach to freshwater effects assessment will be equally protective to saltwater species. There are, for example, no data for important marine taxa such as Echinodermata, Ctenophora and Cephalopoda. Uncertainty as to the sensitivity of these species has led to proposals that a marine predicted no-effect concentration (PNEC) should be derived using larger application factors than those used for the freshwater compartment. Research should be encouraged that will generate data to provide a scientific basis to answer the question, of whether or not an additional safety factor needs to be applied to protect saltwater ecosystems, and if so, the magnitude of any such factor.

The relative sensitivity of life stages is examined. The sensitivity of the whole life-cycle is generally greater than its constituent stages, but for fish it is apparent that juvenile stages exhibit typically the greatest sensitivity.

A valuable aspect of the new database is its improved capacity to examine the extrapolation from acute ecotoxicity data, to levels which are safe after chronic exposure. For more than half the situations examined, an ‘acute to chronic ratio’ of less than 10 is evident. For the vast majority of situations the value 70, compared with the current value of 100, is more than adequate, allowing a generous margin within the total factor (acute:ecosystem = 1000) to allow for extrapolations between the results of chronic studies and safe levels for ecosystems.

Recommendations for further work are included.