March 15, 2016 by Becky Brown

I attended a workshop hosted by the Health and Environmental Sciences Institute (HESI - to discuss existing strategies for effluent toxicity testing, how these vary from country to country, and what agreement there is on a general approach.

Although the general goal of preventing effluents from harming the environment is the same across regions, the way in which effluent testing is conducted is often very different. For example, in developed countries chronic toxicity effects are the main concern whereas acute effects are still an issue for some developing countries. In the US whole organism chronic bioassays generally use fish as an integral part of the regulatory framework on which permits for the release of effluents are based. In Europe, there is a less consistent approach to effluent testing, with EU Member States setting their own standards, and utilising both in vitro and in vivo assays for setting discharge consents. Fish tests are less widely used in Europe, and where they are considered necessary the fish embryo test (FET) is often preferred. At the meeting there was discussion about whether the FET assay could be used as a refinement or replacement for chronic fish assays in effluent toxicity assessments.

Many standardised tools already exist for use in effluent toxicity assessment (e.g. JRC 2013; ISO standard methods) but a number of new developments were discussed at the meeting. The use of fish cell lines as alternatives for whole fish testing and how biomimetic extraction-solid phase micro-extraction analysis (BE-SPME) can be used to interpret effluent effects are examples of such new developments.

I presented wca’s recent work on “Biological effect measures and adverse outcome pathways (AOPS) applied to effluent testing”. A breakout group focussing on effluent assessment for chemicals with specific modes of action agreed that there was sufficient available data on the mode of action of some substances that in vitro receptor based assays, alongside measures of biomarker responses, could be applied in effluents and / or receiving waters as part of a weight of evidence assessment of the causes and adverse effects of effluent toxicity. It was considered that these biomarker techniques should be used alongside traditional whole organism bioassays to aid interpretation of the effects. In order to guide the selection of relevant biological effects tools, as much information as possible should be known about the type and composition of the effluent under consideration.

A critical review of effluent toxicity testing approaches is expected as an output from this meeting, as outlined in the March 2016 HESI monthly report.


Joint Research Council (JRC). 2013. JRC Reference Report on Monitoring of emissions from IED-installations Monitoring of emissions to air and water Industrial Emissions Directive 2010/75/EU (Integrated Pollution Prevention and Control). Final draft report October 2013.

International Standards Organisation (ISO): Water Quality – Biological methods