Toxicity tests within a triad of techniques

Traditionally, environmental assessment has been directed mainly towards chemical characterization, which has resulted in the establishment of guidelines for regulatory purposes. Such parameters lack the dynamic toxicity information needed to determine the bioavailability of contaminants to the biota residing in an ecosystem (Munawar et al., 1989). 

Toxicity tests use biological systems to detect the presence of toxic chemicals in the samples being investigated (e.g. water, effluents, sediments, soil). The term bioassay also is used to describe a toxicity test. The idea is that the response of an organism will be representative of organisms living in the environment where the 

Indicator system Biological Indices Ecological surveys Community structure Physiological techniques Bioaccumulation tests 

Chemical tests can be used in two different ways. They can be regulatory if a limit is specified for a certain substance in an effluent and they can be predictive by calculating, from the discharge, the concentration expected in the environment both are achieved by comparison with established quality guidelines for water, sediment or soil (Scroggins, 1999). 

Chemical analysis, however, continues to be used to assess the quality of industrial and municipal wastes, as well as to assess the limits of concentration or loading that can be applied to the environment. Such limits have been tied to best-treatment performance of waste treatment plants, also termed best available treatment (BAT) and best available treatment economically achievable (BATEA). 

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