Field assessments in conjunction with whole effluent toxicity testing

Whole effluent toxicity (WET) tests are widely used to assess potential eff ects of wastewater discharges on aquatic life. This paper represents a summ ary of chapters in a 1996 Society of Environmental Toxicology and Chemistry -sponsored workshop and a literature review concerning linkages between WET testing and associated field biomonitoring, Most published studies thus fa r focus primarily on benthic macroinvertebrates and an effluent-dominated s tream systems in which effluents demonstrate little or no significant acute toxicity. Fewer studies examine WET test predictability in other aquatic e cosystcms (e.g., wetlands, estuaries, large rivers) or deal with instream b iota such as fish and primary producers. Published results indicate that st andards for the usual WET freshwater test species, Ceriodaphnia dubia and P imephales promelas, may not always protect most of the species inhabiting a receiving stream. Although WET tests are useful in predicting aquatic indi vidual responses, they are net meant to directly measure natural population or community responses. Further, they do not address bioconcentration or b ioaccumulation of hydrophobic compounds: do not assess eutrophication effec ts in receiving systems; and lastly, do not reflect genotoxic effects or fu nction to test for endocrine-disrupting chemicals. Consequently, a more dir ect evaluation of ecosystem health, using bioassessment techniques, may be needed to properly evaluate aquatic systems affected by wastewater discharg es.