Effect-based monitoring of chemical hazards in drinking water from source to tap: seasonal trends over 2 years of sampling

Environmental Sciences Europe

Table 2 Effect-based methods applied, reference compounds and effect concentration levels

Endpoint	Cell line	Stimulant treatment	Reference compound	Cytotoxicity test applied	Threshold for cytotoxicity	%-effect level chosen to define BEQ	International guideline document^a
Androgen receptor agonism (AR ago)	AR-EcoScreen GR-KO M1	–	Dihydrotestosterone (DHT)	MTS	≤ 80% of vehicle control	EC₂₀	OECD 458
Androgen receptor antagonism (AR anta)	AR-EcoScreen GR-KO M1	DHT	Hydroxyflutamide (OHF)	MTS	≤ 80% of vehicle control	IC₃₀	OECD 458
Estrogen receptor agonism (ER)	T47D-ER	–	17β-estradiol (E2)	MTS	≤ 80% of vehicle control	EC₂₀	OECD 455^b
Oxidative stress (Nrf2 activity)	MCF7 AREc32	–	tert-Butylhydroquinone (tBHQ)	MTS	≤ 80% of vehicle control	EC_IR1.5
Aryl hydrocarbon receptor activation (AhR)	DR-EcoScreen	–	2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD)	MTS	≤ 80% of vehicle control	EC₁₀
In vitro micronucleus test (MN)	TK-6	–	Mitomycin C	EMA +	≥ fourfold induction vs vehicle control	Not applicable^c	OECD 487

^a References to international guidelines given for information purposes. Assays were performed with some minor modifications from these guidelines. A full description of the experimental procedures is given in the Supporting Information
^bThe cell line used is not mentioned in OECD 455, but the assay has generally been performed in accordance with the guideline, with minor modifications
^c For genotoxic effects, no BEQ is calculated. The samples are instead evaluated as genotoxic or non-genotoxic based on a > threefold induction vs vehicle control