Endocrine disrupting compounds affecting corticosteroid signaling pathways in Czech and Swiss waters: potential impact on fish.

This study investigated the occurrence of corticosteroid signaling disruptors in wastewaters and rivers in the Czech Republic and in Switzerland. 36 target compounds were detected using HPLC-MS/MS, with up to 6.4 µg/L for azole antifungals that indirectly affect corticosteroid signaling. Glucocorticoid receptor (GR)-mediated activity was determined using the GR-CALUX bioassay with dexamethasone equivalent concentrations ranging from

LC-MS/MS determination of potential endocrine disruptors of cortico signalling in rivers and wastewaters.

A targeted analytical method was established to determine a large number of chemicals known to interfere with the gluco- and mineralocorticoid signalling pathway. The analytes comprise 30 glucocorticoids and 9 mineralocorticoids. Ten out of these corticosteroids were primary metabolites. Additionally, 14 nonsteroids were included. These analytes represent a broader range of possible adverse modes of action than previously reported. For the simultaneous determination of these structurally diverse compounds, a single-step multimode solid-phase extraction and pre-concentration was applied. Extracts were separated by a short linear HPLC gradient (20 min) on a core shell RP column (2.7 µm particle size) and compounds identified and quantified by LC-MS/MS. The method provided excellent retention time reproducibility and detection limits in the low nanograms per litre range. Untreated hospital wastewater, wastewater treatment plant influent, treated effluent and river waters were analysed to demonstrate the applicability of the method. The results show that not all compounds were sufficiently eliminated by the wastewater treatment, resulting in the presence of several steroids (∼20 ng/L) and nonsteroids in the final effluent, some of them at high concentrations up to 200 ng/L. Most of the detected mono-hydroxylated steroidal transformation products were found at significantly higher concentrations than their parent compounds. We therefore recommend to include these potentially bioactive metabolites in environmental toxicity assessment.

Enhancement of AhR-mediated activity of selected pollutants and their mixtures after interaction with dissolved organic matter.

Dissolved organic matter (DOM) in freshwaters is present at concentrations ranging from 0.5 to 50 mg L⁻¹, and consists of various organic compounds, including humic substances (HS). HS exert a variety of direct and indirect biological effects, including interaction with the aryl hydrocarbon receptor (AhR). AhR is a cytosolic receptor that binds various hydrophobic organic compounds (HOCs) and mediates some of their toxic effects. In vitro effects of binary mixtures of various DOM (mainly HS) with various HOCs on AhR-mediated responses were studied by use of H4IIE-luc cells. Six out of 12 DOM activated the AhR even at environmentally relevant concentrations (17 mg L⁻¹). In simultaneous exposures of H4IIE-luc cells to DOM (17 mg L⁻¹) and each of the model compounds, 2,3,7,8-TCDD, PCB126, PCB169, benzo[a]pyrene, benzo[a]anthracene, dibenz[a,h]anthracene, fluoranthene, a mixture of persistent organic pollutants (POPs), a mixture of polycyclic aromatic hydrocarbons (PAHs), and a mixture of all HOCs, either significant additive or facilitative effects were observed when compared to activities of single HOCs. No significant decrease of effects due to possible sorption of HOCs to DOM was observed, even in subsequent experiments when HOCs+DOM mixtures were preincubated for six days before exposure to H4IIE-luc. Thus, DOM does not seem to protect organisms against AhR-mediated toxic effects of HOCs (as usually predicted due to sorption of HOCs on DOM), but it can actually enhance their potency for AhR-mediated effects in some situations.