title: Neurotoxic evaluation of two organobromine model compounds and natural AOBr-containing surface water samples by a Caenorhabditis elegans test.
abstract: Brominated organic compounds are known as disinfection byproducts. Very recently, however, even natural brominated organic compounds (analyzed as adsorbable organic bromine; AOBr) have been found in decaying freshwater cyanobacteria blooms. Among the identified compounds was dibromoacetic acid (DBAA), which has proven to be neurotoxic at rather high concentrations in mammalian assays. Currently it is open how single compounds as well as complex mixtures impact organisms at environmentally realistic concentrations. Furthermore, it is also unclear how natural organic matter, mainly humic substances (HS), which are present in all freshwater systems, modulates the toxic impact of AOBr. Therefore, two AOBr compounds (DBAA and tetrabromobisphenol-A; TBBP-A) and AOBr-containing water samples were tested using a Caenorhabditis elegans neurotoxicity assay that measured autonomic and sensory functions. TBBP-A had an impact on three response variables of C. elegans and can be classified neurotoxic. In contrast to our expectations, DBAA led to neurostimulation of two autonomic functions, but had a temporary impact on the defecation interval. All surface water samples contained measurable amounts of AOBr. Exposure of C. elegans to concentrated water samples - one in particular - increased three of the four locomotion traits and left defecation activity and both sensory variables unchanged. This stimulation might be due to unidentified compounds in the samples or to a hormetic effect of the AOBr compounds. Thermotactic behavior was characterized by a temporary preference for the colder environment, indicating a temporary mild neurotoxicity. Overall, the set of relative simple phenotypic tests used in the current study revealed a meaningful neurotoxic or neurostimulative profile in response to chemical compounds or natural samples. Furthermore, it shows that the resulting response to natural AOBr compounds at environmentally realistic concentrations was not necessarily adverse, but instead, that the mixtures of natural AOBr were neurostimulatory.
authors.affiliation: Key Laboratory of Environmental Medicine Engineering, Ministry of Education, School of Public Health, Southeast University, Nanjing 210009, China; Department of Biology, Freshwater and Stress Ecology, Humboldt-Universität zu Berlin, Späthstr. 80/81, 12437 Berlin, Germany.
authors.forename: Jingjuan
authors.initials: J
authors.lastname: Ju
authors.affiliation: Department of Biology, Freshwater and Stress Ecology, Humboldt-Universität zu Berlin, Späthstr. 80/81, 12437 Berlin, Germany.
authors.forename: Thora
authors.initials: T
authors.lastname: Lieke
authors.affiliation: Department of Biology, Freshwater and Stress Ecology, Humboldt-Universität zu Berlin, Späthstr. 80/81, 12437 Berlin, Germany.
authors.forename: Nadine
authors.initials: N
authors.lastname: Saul
authors.affiliation: Key Laboratory of Environmental Medicine Engineering, Ministry of Education, School of Public Health, Southeast University, Nanjing 210009, China.
authors.forename: Yuepu
authors.initials: Y
authors.lastname: Pu
authors.affiliation: Key Laboratory of Environmental Medicine Engineering, Ministry of Education, School of Public Health, Southeast University, Nanjing 210009, China.
authors.forename: Lihong
authors.initials: L
authors.lastname: Yin
authors.affiliation: Chair of Water Quality Control, Technische Universität Berlin, Straße des 17, Juni 135, 10623 Berlin, Germany.
authors.forename: Cindy
authors.initials: C
authors.lastname: Kochan
authors.affiliation: Chair of Water Quality Control, Technische Universität Berlin, Straße des 17, Juni 135, 10623 Berlin, Germany.
authors.forename: Anke
authors.initials: A
authors.lastname: Putschew
authors.affiliation: Department of Biology, Freshwater and Stress Ecology, Humboldt-Universität zu Berlin, Späthstr. 80/81, 12437 Berlin, Germany.
authors.forename: Nora
authors.initials: N
authors.lastname: Baberschke
authors.affiliation: Department of Biology, Freshwater and Stress Ecology, Humboldt-Universität zu Berlin, Späthstr. 80/81, 12437 Berlin, Germany. Electronic address: christian_ew_steinberg@web.de.
authors.forename: Christian E W
authors.initials: CE
authors.lastname: Steinberg
mesh_terms: D000085:Acetates / Q000633:toxicity*; D000818:Animals; D017173:Caenorhabditis elegans / Q000187:drug effects*; D005618:Fresh Water / Q000737:chemistry; D009474:Neurons / Q000187:drug effects; D011075:Polybrominated Biphenyls / Q000633:toxicity*; D018675:Toxicity Tests; D014874:Water Pollutants, Chemical / Q000633:toxicity*
chemical_list: D000085:Acetates; D011075:Polybrominated Biphenyls; D014874:Water Pollutants, Chemical; C088674:dibromoacetic acid; C020806:tetrabromobisphenol A
keywords: AOBr; Autonomic function; Cyanobacteria; Organobromine compounds; Sensory function; Surface water samples