Table 1.

- Suggested ways forward to expedite and better target AOP development.

Activity	Description	Notes, examples
Raising awareness of AOPs among early-stage researchers	Specific courses and trainings, AOPs included in toxicology curricula, offer dedicated workshops, organise theoretical and practical (hands-on) courses at relevant scientific conferences (e.g. SETAC, SOT).	Available resources for AOP training can be found on the AOP forum https://aopwiki.org/forums/showthread.php?tid=18Sections on AOPs have been proposed within summer courses (e.g., organized by HBM4EU or university of Ottawa).
International concerted actions for selected AOP projects	Providing guidance and incentives to researchers and regulators for efficient development of priority AOPs and fostering collaborative efforts.	Modelling the COVID-19 pathogenesis with AOPs - CIAO project (https://www.ciao-covid.net/).
Development of smaller units (e.g., KERs)	Generating new AOPs and AOP networks through small and easily manageable efforts. Drafting of putative AOPs could also foster continuation by other authors.	Svingen et al. (2021)
Prioritize the development of new AOPs that address RA needs and cover gaps	Priority focus on AOPs explaining exposure-health associations from epidemiological studies. Similarly, BoEs from human studies can be used to identify a KE, triggering the development of new AOPs/AOP networks.	van den Brand et al. (2022)
Involve risk assessors and risk managers in the selection of AOPs that are most needed	Dedicated discussions of OECD bodies, such as the Working Party for Hazard Assessment (WPHA), the Working Group of the National Coordinators for the Test Guidelines Programme (WNT) and the Working Party on Manufactured Nanomaterial (WPMN).	Stakeholders may recommend focusing on a particular substance/AO and feel integrated into the process of development. The engagement strategy within the field of radiation research and regulation is one example (Chauhan et al., 2022).
Foster collaboration with scientific journals to allow the publication of AOP reports alongside creation of an AOP page in the AOP-Wiki	Ongoing initiative promoted by the OECD (e.g. https://youtu.be/Tl1bVpZNYJY). AOP developers prepare a peer-reviewed publication in the format of a citable AOP report (O'Brien and Yauk, 2022).	The first AOP reports were published recently (AOP 296 (Cho et al., 2022), AOP 263 (Song and Villeneuve, 2021), AOP 360 (Schmid et al., 2021)). Development of memorandums of understanding with additional journals are ongoing.
Recognize AOPs in the AOP-Wiki as important scientific records themselves	Current discussion (Ritchie, 2022) and implementation of principles of findability, accessibility, interoperability, and reusability (FAIR) suggest that other reporting formats than classical scientific papers may support timely, open access and flexible reporting of new AOPs.	AOP-Wiki is an open living platform that might be better suited for sharing knowledge in modern science.
Derive new AOPs from physiological maps	The physiological maps describe underlying mechanisms of human physiology of a relevant organ at the molecular and cellular level.	Vinken et al. (2021)