Effect-directed analysis (EDA) of genotoxic and thyroid hormone-disrupting compounds in abiotic and biotic samples from aquatic ecosystems

Extracts from various abiotic samples (i.e. passive sampling silicone rubber [SR] sheets, sediments, suspended particulate matter [SPM]) and biotic samples (i.e. whole body homogenates from different species) were screened for genotoxicity in the Ames fluctuation assay and Comet assay, and for transthyretin (TTR)-binding potency in the 125 I-T4-TTR binding assay. Biota samples showed high cytotoxicity in both Ames and Comet assay, which hampered the quantification of the genotoxic activities. TTR-binding activities were found in all samples. Causative compounds were investigated by means of effect-directed analysis (EDA) in the selected SR sheet and biota samples. The extracts were fractionated on a reverse-phase (RP) column and the RP fractions that showed TTR-binding activities were analyzed by liquid chromatography time-of-flight mass spectrometry (LCToF-MS). A number of known TTR-binding contaminants, such as hydroxylated polychlorinated biphenyls (OH-PCBs), musks, polycyclic aromatic hydrocarbon (PAH) derivatives, nonsteroidal anti-inflammatory drugs (NSAIDs), perfluoroalkyl substances (PFASs), triclosan and nonylphenol were tentatively identified in the extracts from the selected SR sheet and biota extracts using mass lists. Citalopram and fluconazole were also analytically confirmed as emerging contaminants in the extracts, but showed no affinity in the TTR-binding assay. However, the presence of pharmaceuticals in passive sampling sheets and biotic samples is highly interesting, given their possible potential for bioaccumulation and their unknown potential risk to aquatic species.