Towards toxicity assessment without animals: The use of Adverse Outcome Pathways


Towards toxicity assessment without animals: The use of Adverse Outcome Pathways

7 February 2022
On Tuesday 25 January 2022, the Organisation for Economic Co-operation and Development (OECD) hosted a webinar on cooperative activities between Scientific journals and the OECD on Adverse Outcome Pathway (AOP).

An AOP is a sequence of key events linking a molecular initiating event to an adverse outcome across different levels of biological organisation (i.e. cell, tissue, organ). AOPs are knowledge management tools in toxicology and are useful to support human health risk assessment. They are also valuable in helping to avoid animal testing through the use of alternative methods.

The objectives of the OECD Chemical Safety Programme are to help countries develop and implement policies and instruments that make their chemical management systems as effective and robust as possible, while protecting human health and the environment. In this context, the OECD launched in 2012 a new programme on the development of AOPs to facilitate the collection of mechanistic information from toxicological science in a structured way, to help establish causal relationships between the molecular and cellular events that lead from disruption of biology by stressors to adverse effects, and to identify critical data gaps in understanding these pathways.

This AOP framework enables a new systematic approach to the collection, organisation and evaluation of toxicity information. AOPs support non-animal methods by focusing on predicting adverse outcomes using mechanistic data generated by in vitro, in chemico and in silico techniques. This allows for an understanding of toxic effects (adverse outcomes) as a process, in contrast to animal testing which reveals toxic effects in a species without explaining the underlying mechanisms. 

In October 2021 and January 2022, two scientific journals, ‘Environmental Toxicology and Chemistry’ and ‘Environmental and Molecular Mutagenesis’ signed a Memorandum of Understanding with the OECD on cooperative activities in the field of AOP development, in order to increase the number of AOPs developed, reviewed and published in accordance with the OECD quality standards described in the Guidance Document for the scientific review of AOPs

The first two AOPs that have followed this pathway were accepted by Environmental Toxicology and Chemistry recently and the corresponding papers are published in a Virtual issue entitled ‘AOP Pathways & Predictions’.

The objective of this webinar was to present the basis for cooperation between scientific journals and the OECD and to discuss the lessons learned so far.

To go further:

A video recording and the presentations (see below) of the webinar are now available.

  • The AOP framework: Dan Villeneuve (US EPA) presented the AOP framework and challenges faced | Presentation.

  • The importance of cooperation: Based on the results of a recent workshop held on ‘Science with impact in an era of information overload’, Clemens Wittwehr (EC Joint Research Centre) stressed the importance of an increased cooperation between all stakeholders in order to promote the application of the AOP framework | Presentation.

  • The OECD AOP review and endorsement process: Nathalie Delrue (OECD Secretariat) presented the review principles and approval process of the OECD AOP and described how cooperation between the OECD and scientific journals is formalised in the terms of a Memorandum of Understanding | Presentation.

  • Case study and Lessons learned from ET&C and EMM: Dries Knapen (University of Antwerp, Belgium) and Jason O’Brien (National Wildlife Research Centre, Canada) presented the lessons learned from the pilot study conducted at Environmental Toxicology and Chemistry (ET&C) and at Environmental and Molecular Mutagenesis (EMM), with the first AOPs and how the journal review process was optimised in this context | Presentation.