The NORMAN interlaboratory study on biotesting of spiked water extracts

The NORMAN network is a permanent self-sustaining network for the monitoring and biomonitoring of emerging environmental contaminants. The NORMAN working group on Bioassays (Bio WG) focuses on the application of bioanalytical tools for environmental quality monitoring. A main objective is to provide recommendations for the implementation of effect-based tools into regulatory frameworks. In this context, a blind interlaboratory study (ILS) was performed. The aim was to verify if a bioassay battery conducted in different laboratories following own protocols would produce comparable results when testing spiked surface water extracts. The lead in planning and organizing was taken by the Department of Ecosystem Analysis (ESA), RWTH Aachen University (DE). The ILS bioassay battery included acute-toxicity assays with organisms from different trophic levels (Algae, Daphnia, Zebrafish embryos); and mechanism-specific bioassays for estrogenicity (YES, ER-Luc cell lines) and mutagenicity (Ames fluctuation) assessment. Three to four participants performed each bioassay, including: BfG (DE), Waternet (NL), Waterproef (NL), INERIS (FR), IFREMER (FR), RECETOX (CZ), ISSeP (BE), ITM (SE), IVM-VU (NL), Entox/University of Queensland (AU), Ecotox Centre (CH), ESA-RWTH (DE). Clean water from a reference site was concentrated 10.000 times with large volume solid-phase extraction. Four emerging pollutants were used for spiking: triclosan, acridine, 3-nitrobezanthrone and 17-alpha-ethinylestradiol. Extracts were spiked with either single chemicals or a mixture, in concentrations aimed to produce full dose-response curves in bioassays. The spiked extracts were prepared, separated in aliquots, identified with codes, and sent to the participating laboratories. Standardized bioassay methods (OECD, ISO) were recommended but not mandatory, and biotesters could use their own protocols. Results were sent to RWTH, and a summary of the full ILS was provided to the ILS participants. In October 2014, a workshop was held at RWTH Aachen to present and discuss the ILS results. Bioassays produced mostly highly comparable results, even when protocols differed significantly. Suggestions for future improvements include harmonization of methods for data analysis and results evaluation. An important expected outcome of the ILS is the promotion of biotesting for water quality monitoring at the level of European policy-makers.