Aquatic field studies in ecotoxicological assessment of hazardous substances

The role of field tests for chemical management must not be overestimated. Results obtained from multi species tests in the field indisputably give valuable information on the fate of a substance that facilitates the assessment of results from laboratory tests provided the test design is orientated on the appropriate formulation of question. If those investigations are available, they are included in the assessment of substances. These may increase the uncertainty factor, but this can only be a critical case-by-case decision. The investigations, however, have to satisfy certain minimum requirements: —examination of several test concentrations and untreated controls, proof of a dose–effect relationship, ability to derive the NOEC; —exposure of several taxonomic groups over a longer period; —analytical control of the test concentration during the experiment; —equivalent development of controls, ability to repeat the experiments under different starting conditions; and —use of aquatic ecological parameters as toxicological end points. Independently of these requirements, the necessity of validation does in principle exist. © 1994 by John Wiley & Sons, Inc..