Importance of internal biotic concentrations in risk evaluations with aquatic systems

Ecological risk evaluations are commonly performed using aqueous concentrat ions and aqueous toxicity measurements as a starting point. However risk ev aluations could be carried out using internal biotic concentrations and the internal lethal or sublethal concentrations. This has several advantages. Firstly, the internal lethal and sublethal concentrations are relatively co nsistent in groups of chemicals having a similar mode of action. Thus in fi eld situations the internal concentration, in fish and possibly other biota , can be used to evaluate possible biotic effects. Also other histopatholog ical, biochemical, biomolecular and physiological effects can be assessed a nd used with this information to give an overall assessment. There are, how ever, several limitations with this approach including sensitivity, health, age and nutritional status of the biota as well as a lack of data on dose/ response relationships with internal concentrations. (C) 1999 Elsevier Scie nce Ltd. All rights reserved.