Interferences in the yeast estrogen screen (YES) assay for evaluation of estrogenicity in environmental samples, chemical mixtures, and individual substances

The Yeast Estrogen Screen (YES) has a specific mechanism of action that allows for the analysis of estrogenic EDC at low concentrations, and it has been broadly used to estimate the estrogenic potential of environmental samples. However, the experimental parameters of this assay still demand an investigation, such as cell density, incubation time, wavelength on the experimental outcome, cytotoxicity, and estrogenic activity adsorbed on suspended solids. We studied these interferences and applied the assay to single substances, mixtures, and environmental matrices from different sources. The increase in cell density amplifies the assay sensitivity only to a limited extent, while the reduction in incubation time decreased assay sensitivity -although it was not sig-nificant for surface water, no differences were observed between estradiol-equivalents derived of 48 h and 72 h measurements. The particulate phase was of utmost importance for the total estrogenic activity of the landfill leachate and surface water. Surface waters, landfill leachates and sediments also showed antiestrogenic activity and the integration of both estrogenic and antiestrogenic endpoints provided deeper insights into the potential risk associated with EDC. This study elucidated experimental interferences that may arise during the imple-mentation and use of this assay, bringing more understanding to experimental parameters during the application of the assay for estrogenicity screening.

Automated summary

The Yeast Estrogen Screen (YES) is commonly used to estimate the estrogenic potential of environmental samples. In this study, we investigated the experimental parameters of the assay and applied it to different substances and matrices. We found that cell density and incubation time affect the assay sensitivity, and the particulate phase is important for estrogenic activity. The integration of estrogenic and antiestrogenic endpoints provides deeper insights into the potential risk associated with EDC.