Evaluation of the suitability of recombinant yeast-based estrogenicity assays as a pre-screening tool in environmental samples

This paper presents a study evaluating the suitability of recombinant yeast-based estrogenicity assays as a pre-screening tool for monitoring of the chemical status of water bodies in support of the Water Framework Directive (WFD). Three different recombinant yeast-based assays were evaluated; the Yeast Estrogen Screen (YES), the Recombinant Yeast Assay (RYA) and the Rikilt Estrogen bioAssay (REA), of which the YES assay was employed by two different laboratories. No significant difference between the performance of neither the different laboratories, nor the different yeast-assays was observed.Six batches of eleven samples each were analysed one week apart by the four participating laboratories and the robustness, repeatability and reproducibility of the participating yeast-based assays were evaluated.The setup included a correlation between bioassay results and results from chemical target analysis, which gave valuable information in the evaluation of the assays' performance. A good agreement was found between chemical and bioassay results, showing that the yeast-based assays can give valuable information in WFD work. However, the low sensitivity of the assays towards alkylphenols needs to be significantly improved if they are to be used for monitoring of these compounds. The study further led to suggestions on ways to improve traceability and quality assurance of the yeast-based assays.