Publication Abstract

This report summarises the discussions of an international workshop that took place in May 2024, which aimed to inform the development of a proposal for an Organisation for Economic Cooperation and Development (OECD) Guidance Document on vitellogenin (VTG) analysis and assessment. VTG, an egg-yolk precursor protein found in oviparous species, is an informative marker of possible chemical-induced endocrine activity (particularly estrogenicity, via induction of VTG in males). The measurement of VTG is included in several standardised test guidelines published by the OECD and United States Environmental Protection Agency for the assessment of endocrine activity of chemicals in fish (and one in amphibians). However, in vivo VTG data across and within fish species can be highly variable and influenced by both technical and biological factors, affecting the reliability and interpretation of the results. This poses a challenge for regulatory decision making and can trigger potentially unnecessary vertebrate studies or prevent necessary further investigations. The workshop brought together 42 experts from different sectors and geographies, to discuss three key aspects regarding VTG assessment: 1) technical/laboratory factors and VTG quantification; 2) data handling and statistics, and 3) interpreting the biological plausibility of VTG responses. The workshop participants discussed the development and needs of a Guidance Document to provide harmonised recommendations, best practices, quality assurance criteria, and minimum reporting standards for VTG assessment in regulatory studies across the different test guidelines. Several areas were identified where further work and discussion are needed to inform on the development of the Guidance Document, such as the use of historical control data, the identification of potential outliers, the presentation of data, and analysis of case study examples. Provision of such a Guidance Document would further support the use of VTG as a relevant marker of endocrine activity for regulatory decision making.

Natalie Burden, Catherine Aubee, Jacqueline Augusiak, Marta Baccaro, Svenja Boehler, Francois Brion, Rebecca J Brown, Katherine K. Coady, Zhichao Dang, Elke Eilebrecht, Mike Fryer, Teresa Fagundes, Tom Fisher, Zhenglei Gao, Tracey Goodband, Markus Hecker, Henrik Holbech, Stefan Hoeger, Miriam Jacobs, Oliver Koerner, Ioanna Katsiadaki*, Philippa Kearney, Julie Krzykwa, Joseph Marini, Richard Maunder, Samuel K. Maynard, Valentin Mingo, Frank Mikkelsen, Grace H. Panter, Audrey Pearson, Francesca Pellizzato, Daniel B. Pickford, Edward R. Salinas, Suzanne Schneider, Amy Snow, Fiona Sewell, Petra Stahlschmidt, Karen Thorpe, Daniel L. Villeneuve, Lennart Weltje, James R. Wheeler, Hiroshi Yamamoto.