Validation of the REA bioassay to detect estrogenic activity in the water cycle

• Published in: Toxicology in vitro 2011-12, Vol.25 (8), p.2003-2009
• Main Authors: Nguyen, Mai Thao, van der Oost, Ron, Bovee, Toine F.H.
• Format: Article
• Language: English
• Subjects: Aquatic environment; Biological Assay - methods; drinking-water; Endocrine disruption; Endocrine Disruptors - metabolism; endocrine-disrupting compounds; Environmental Monitoring - methods; Estrogen Receptor alpha - metabolism; Estrogenic activity; Estrogens - metabolism; fish; Fluorescence; green fluorescent protein; Green Fluorescent Proteins - metabolism; liquid-chromatography; mass-spectrometry; Reproducibility of Results; treatment plants; Waste Disposal, Fluid; waste-water; Water cycle; Water Pollutants, Chemical - metabolism; Water Supply - analysis; Yeasts - metabolism
• ISSN: 0887-2333; 1879-3177
• DOI: 10.1016/j.tiv.2011.07.011

► The REA assay was validated as a qualitative screening assay for estrogenic activity in water. ► The procedure was sensitive and specific, not influenced by androgens or progesterones. ► The LOQ of the procedure is below 1ngEEQ/L, sufficient for water threshold levels. ► Some WWTP effluents showed a clear estrogenic response above LOQ. ► No significant amounts of conjugated estrogens were present in these water samples. Endocrine disrupting compounds (EDCs) with estrogenic potency contaminate water and might eventually cause adverse effects to the aquatic environment. Many estrogenic compounds are not completely removed by wastewater treatment systems and, together with the run-off from agricultural areas, they enter surface waters. Chemical analytical methods to determine these compounds are usually expensive and laborious. Therefore, screening bioassays which are able to detect compounds based on their effects offer a solution for prior selection of samples that need to be chemically analyzed. In this study, the REA (RIKILT yeast Estrogen bioAssay), which has been developed to detect estrogenic compounds in calf urine and animal feed at RIKILT, is validated at the Water Board Laboratory of Waterproef for water samples. According to EC Decision 2002/657, detection capability CCβ, specificity and stability have to be determined for the internal validation of a qualitative screening test. In addition, surface water and effluent samples were analyzed to further demonstrate the applicability of the validated test procedure. Results demonstrate that the REA assay is reproducible and specific for estrogenic compounds in water and meets the criteria as prescribed in EC Decision 2002/657. The assay was sensitive enough to detect estrogenic activity of pollutants in water with a limit of quantification (LOQ) below 1ngEEQ/L. This means that samples can be compared with preliminary threshold levels for drinking water and surface waters (7 and 1ngEEQ/L, respectively). The stability of estrogenic activity in water samples is at least 4weeks, when stored at 4°C.