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MA3 WET Testing
(025) Useful methods to understand complex mixture toxicity of effluents from wastewater treatment plants.
Belanger, S1, Nuck, B1, Gausman, M1, Brill, J1, Price, B1, Rawlings, J1, Federle, T1, 1 Procter & Gamble, Cincinnati, OH, USA
ABSTRACT- Many surfactants used in consumer product applications are themselves complex mixtures. Because of varying compositions of commercial anionic or non-ionic surfactants used across industry the environmental distributions may comprise as many as 200 homologues. Physical-chemical properties differ for each homologue that is present. This represents a particular problem for risk assessments constructed for the surfactant when fate and effects of each homologue contribute differentially. Toxicity tests will usually be conducted on commercial forms of the surfactant and the ultimate environmental distribution leaving sewage treatment may be substantially different. In this paper we present the rationale and some supporting evidence for use of coupled laboratory model wastewater treatment systems (porous pots, continuous activated sludge units, etc.) used to simulate environmentally realistic homologue distributions for use in laboratory toxicity studies. The work can be applied to assess complex mixtures defined as entire down-the-drain use of a cleaning product application. Results can be used to compare environmental compatibility of alternative product formulations as well as predict the totality of environmental fate and single species aquatic toxicity in a single test environment. Further, this work can potentially be extended to assess uptake, elimination, and biotransformation of complex surfactant mixtures in whole organisms. This takes the effluent exposure to a logical next step in understanding the environmental risk of surfactant mixtures at the single species level. Limitations and advantages to these approaches will also be presented related to complex surfactant mixture risk assessments.
Key words: mixture, whole effluent toxicity, surfactant, treatability
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