ABSTRACT

The limitations of different approaches to environmental hazard evaluation are illustrated with brief accounts of four case studies. In predictive environmental hazard evaluations, it is customary to make use of data on the three basic properties of a substance: its persistence, its toxicity, and its distribution among environmental matrices. The single most important feature that should be incorporated into the design of experiments on microbial degradation and transformation is a maximal degree of environmental realism. Assessment of partitioning between environmental phases may be carried out at different levels of sophistication. The use of assays for acute toxicity using fish belongs to the historical past; the concentration of a toxicant that kills 50% of the population is no longer an environmentally acceptable measurement of toxic effects on natural ecosystems. The term critical loading has been used to imply that ecosystems are able to survive environmental impacts providing these are lower than a certain critical threshold level.