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The estrogenic activity of the chemical UV-filters, 4-methylbenzylidene camphor (4-MBC) and octyl methoxy cinnamate (OMC) was investigated in an in vivo rainbow trout (Oncorhynchus mykiss) assay. Plasma vitellogenin concentrations were quantified by means of an Enzyme Linked Immuno Sorbent Assay (ELISA) in juvenile rainbow trout before and after intraperitoneal injection of the test compounds. Injection of 4-MBC on day 0, 3, 6 and 10 in the exposure period caused dose and time dependent increases in the concentration of plasma vitellogenin. Significant elevation of vitellogenin concentrations in plasma was demonstrated from 151 mg 4-MBC kg⁻¹ injection⁻¹. Logistic regression analysis relating the percentage of responding fish to the injected dose of 4-MBC resulted in ED10, ED50 and ED90 values of 37, 115 and 194 mg kg⁻¹ injection⁻¹, respectively, after 14 days of exposure (4 injections). Injections with OMC (up to 202 mg kg⁻¹ injection⁻¹) did not result in a statistically significant response in groups of exposed fish, although some individual fish showed elevated concentrations of vitellogenin in plasma. The results confirm that 4-MBC is estrogenic in fish in vivo.
ERGO (EndocRine Guideline Optimization) is the acronym of a European Union-funded research and innovation action, that aims to break down the wall between mammalian and non-mammalian vertebrate regulatory testing of endocrine disruptors (EDs), by identifying, developing and aligning thyroid-related biomarkers and endpoints (B/E) for the linkage of effects between vertebrate classes. To achieve this, an adverse outcome pathway (AOP) network covering various modes of thyroid hormone disruption (THD) in multiple vertebrate classes will be developed. The AOP development will be based on existing and new data from in vitro and in vivo experiments with fish, amphibians and mammals, using a battery of different THDs. This will provide the scientifically plausible and evidence-based foundation for the selection of B/E and assays in lower vertebrates, predictive of human health outcomes. These assays will be prioritized for validation at OECD (Organization for Economic Cooperation and Development) level. ERGO will re-think ED testing strategies from in silico methods to in vivo testing and develop, optimize and validate existing in vivo and early life-stage OECD guidelines, as well as new in vitro protocols for THD. This strategy will reduce requirements for animal testing by preventing duplication of testing in mammals and non-mammalian vertebrates and increase the screening capacity to enable more chemicals to be tested for ED properties.
- Department of Biology
About Henrik Holbech
- Henrik Holbech currently works at the Department of Biology, University of Southern Denmark. Henrik does research in Xenobiology and Endocrinology. Current projects include 'Improvement of methodologies involved in assessment of organism viability in ships' treated ballast water contributing to overall quest in preventing the spreading of aquatic invasive species' and the EU Horizon 2020 project, ERGO, investigating new biomarkers and endpoints to identify thyroid disrupting chemicals in different vertebrate classes including mammals, fish and amphibians.