Selection criteria for bioassays

The relative importance of selection criteria for screening tests and ecologically predictive tests is indicated in Table 10.1. Ambiguous items are discussed below. 

A high level of sensitivity to a wide range of toxicants is required for screening tests in order to minimise false negative results. Since one sensitive species for all possible contaminants and scenarios does not exist, the application of more than one species (test battery comprising several sensitive bioassays) is recommended in order to cover a wide range of pollutants. 

The availability of sufficient and suitable test organisms is a major criterion for the practical application of a specific test. If not commercially available (e.g. various test kits including test organisms that can be cultured upon demand 

High sensitivity Required Dependent on assessment endpoint 

The influence of the reference soil on the test result depends on the type of effects measured. Generalisation may be difficult but usually severe effects (lethality) are less influenced by the soil matrix than sub-lethal effects (e.g. mortality of earthworm compared to growth of plants). 

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