title: Characterization of AhR agonists reveals antagonistic activity in European herring gull (Larus argentatus) eggs.
abstract: European herring gull (Larus argentatus) eggs from two Norwegian islands, Musvær in the south east and Reiaren in Northern Norway, were screened for dioxins, furans, and dioxin-like and selected non-dioxin-like polychlorinated biphenyls (PCBs), and subjected to non-target analysis to try to identify the aryl hydrocarbon receptor (AhR) agonists, responsible for elevated levels measured using the dioxin responsive chemically activated luciferase expression (DR-CALUX) assay. Eggs from Musvær contained chemically calculated toxic equivalent (WHO TEQ) levels of between 109 and 483 pg TEQ/g lw, and between 82 and 337 pg TEQ/g lw was determined in eggs from Reiaren. In particular PCB126 contributed highly to the total TEQ (69-82%). In 19 of the 23 samples the calculated WHO TEQ was higher than the TEQCALUX. Using CALUX specific relative effect potencies (REPs), the levels were lower at between 77 and 292 pg/g lw in eggs from Musvær and between 55 and 223 pg/g lw in eggs from Reiaren, which was higher than the TEQCALUX in 16 of the 23 samples. However, the means of the REP values and the TEQCALUX were not significantly different. This suggests the presence of compounds that can elicit antagonist effects, with a low binding affinity to the AhR. Non-target analysis identified the presence of hexachlorobenzene (HCB) (quantified at 9.6-185 pg/g lw) but neither this compound nor high concentrations of PCB126 and non-dioxin-like PCBs could explain the differences between the calculated TEQ or REP values and the TEQCALUX. Even though, for most AhR agonists, the sensitivity of herring gulls is not known, the reported levels can be considered to represent a risk for biological effects in the developing embryo, compared to LC50 values in chicken embryos. For human consumers of herring gull eggs, these eggs contain TEQ levels up to four times higher than the maximum tolerable weekly intake.
authors: Norwegian Institute for Water Research (NIVA), Gaustadalleen 21, N-0349 Oslo, Norway; University of Oslo, Dept. of Bioscience, Postboks N-0316 Blindern, Oslo, Norway. Electronic address: martine.muusse@niva.no.
authors: Martine
authors: M
authors: Muusse
authors: Akvaplan NIVA, Fram Centre, N-9296 Tromsø, Norway.
authors: Guttorm
authors: G
authors: Christensen
authors: Norwegian Institute for Water Research (NIVA), Gaustadalleen 21, N-0349 Oslo, Norway.
authors: Tânia
authors: T
authors: Gomes
authors: Research Centre for Toxic Compounds in the Environment, Faculty of Science, Masaryk University, Kamenice 753/5, 625 00 Brno, Czech Republic.
authors: Anton
authors: A
authors: Kočan
authors: Norwegian Institute for Water Research (NIVA), Gaustadalleen 21, N-0349 Oslo, Norway.
authors: Katherine
authors: K
authors: Langford
authors: Norwegian Institute for Water Research (NIVA), Gaustadalleen 21, N-0349 Oslo, Norway.
authors: Knut Erik
authors: KE
authors: Tollefsen
authors: Research Centre for Toxic Compounds in the Environment, Faculty of Science, Masaryk University, Kamenice 753/5, 625 00 Brno, Czech Republic.
authors: Lenka
authors: L
authors: Vaňková
authors: Norwegian Institute for Water Research (NIVA), Gaustadalleen 21, N-0349 Oslo, Norway.
authors: Kevin V
authors: KV
authors: Thomas
mesh_terms: D000818:Animals; D015415:Biomarkers / Q000378:metabolism; D046091:Charadriiformes / Q000378:metabolism*; D004147:Dioxins / Q000032:analysis / Q000378:metabolism; D004531:Eggs; D004784:Environmental Monitoring / Q000379:methods*; D004785:Environmental Pollutants / Q000032:analysis / Q000378:metabolism*; D009664:Norway; D010063:Ovum / Q000737:chemistry* / Q000378:metabolism; D018336:Receptors, Aryl Hydrocarbon / Q000378:metabolism*
chemical_list: D015415:Biomarkers; D004147:Dioxins; D004785:Environmental Pollutants; D018336:Receptors, Aryl Hydrocarbon
keywords: Aryl hydrocarbon receptor agonists; Dioxins; European herring gull eggs; Furans; PCBs