Effect Based Monitoring in Water Safety Planning - Effect-based trigger values for different water quality classes considering hazards for human and the environment health

“In vitro bioassays are highly sensitive and some can detect effects in clean water samples. Effect- based trigger values (EBTs) can be applied to distinguish an acceptable response in a water sample from an unacceptable response. This report reviews different approaches used to derive EBTs for the protection of both human health (e.g., drinking water and recycled water for indirect potable use) and ecosystem health (e.g., surface water and wastewater). The approaches applied range from simple translation from existing guideline values or acceptable daily intake values to approaches that determine the in vitro effect at the guideline value concentration and considers mixture effects. Other approaches apply multiple lines of evidence or compare experimental in vitro and in vivo responses to derive EBTs. Some approaches are only suitable for drinking water or assays where few potent chemicals dominate the effect, while other approaches can be applied to any water type with guideline values and any assay.
The majority of EBTs have been derived for assays indicative of estrogenic activity, with surface water EBTs for six different mammalian reporter gene assays. It is recommended to use assay- specific EBTs rather than a generic EBT for an endpoint as differences in assay sensitivity and chemical potency can result in different EBTs. There are fewer EBTs available for assays indicative of xenobiotic metabolism or adaptive stress responses, with no EBTs expressed in bioanalytical equivalent concentrations for genotoxicity or mutagenicity assays. Further, there are more EBTs for surface water compared to drinking water. However, EBTs derived from guideline values for surface water are expected to also be protective for drinking water.”

(Citation: Neale, P., Leusch, F., Escher, B. – Effect Based Monitoring in Water Safety Planning – Effect-based trigger values for different water quality classes considering hazards for human and the environment health – GWRC EBM in WSP – WP3.4 (2020))