The assessment of the actual impact of discharged wastewater on the whole ecosystem and, in turn, on human health requires the execution of bioassays. In effect, based on the chemical characterization alone, the synergistic/antagonistic effect of mixtures of pollutants is hardly estimable. The aim of this work was to evaluate the applicability of a battery of bioassays and to suggest a smart procedure for results representation. Two real wastewater treatment plants were submitted to analytical campaigns. Several baseline toxicity assays were conducted, together with tests for the determination of endocrine activity, genetic toxicity and carcinogenicity of wastewater. A “traffic light” model was adopted for an easy-to-understand visualization of the results. Although the legal prescriptions of chemical parameters are fully complied with, bioassays show that a certain biological activity still residues in the treated effluents. Moreover, influent and effluent responses are not always appreciably different. Some tests employing human cells were revealed to be only partially adequate for environmental applications. An interesting and helpful development of the present approach would consist in the estimation of biological equivalents of toxicity, as shown for the estrogenic compound 17-β-estradiol.

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The assessment of the environmental footprint of an organization or product is based on methods published by the European Union Joint Research Centre, which take 16 impact areas into account. Among the listed categories are human and freshwater ecosystem toxicities. Standard protocols utilize just chemical parameters as input data, hindering the determination of the full impact of complex mixes, such as pollutants released into the environment. Biological assays enable us to overcome this gap: in the present work, assays were employed to determine both baseline and specific toxicity to aquatic species (green algae, luminescent bacteria, and crustacean cladocera) as well as specific toxicity (mutagenicity and carcinogenicity). Ecological footprint was estimated with regard to the impact categories “freshwater toxicity” and “human cancer toxicity” following the standard methodology. In parallel, the impact on the above categories was estimated using the results of biological assays as input. Standard and bioassay-based results are not always congruent, and conventional methods generally underestimate the effects. Likewise, the choice of reference substance (metals or organics) influences the quantification of impact. Appropriate batteries of biological assays could therefore be utilized to complement LCA (Life Cycle Assessment) techniques in order to make them more sensitive when considering toxicity in mid-term impact categories.

The assessment of an organization/product's environmental footprint is based on the protocols developed by the Joint Research Centre of the European Union, which take into account 16 impact categories. Among the categories covered are toxicity to freshwater ecosystems and to humans. Standard protocols use only chemical parameters as input data, preventing the true impact of entire complex mixtures, such as emissions discharged into the environment, from being determined. Biological assays allow us to bridge this gap: in the current study, assays were used to determine baseline toxicity towards aquatic organisms (green algae, luminescent bacteria, and crustaceans) as well as specific toxicity (mutagenicity and carcinogenicity). Expected impacts were compared using two approaches (standard and bioassay-centered results obtained are not always in line and, in general, the traditional method underestimates impacts). This demonstrates the importance of these assays and suggests that they be used in LCA (Life Cycle Assessment) protocols as well.

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