Help: AOPs

A Create a new AOP


A descriptive phrase which references both the Molecular Initiating Event and Adverse Outcome. It should take the form “MIE leading to AO”. For example, “Aromatase inhibition leading to reproductive dysfunction” where Aromatase inhibition is the MIE and reproductive dysfunction the AO. In cases where the MIE is unknown or undefined, the earliest known KE in the chain (i.e., furthest upstream) should be used in lieu of the MIE and it should be made clear that the stated event is a KE and not the MIE.

Handbook Entry

Short name

A name that succinctly summarises the information from the title.

This name should not exceed 90 characters.

Handbook Entry


Text describing AOP Licenses will go here

B Graphical Representation of the AOP

Graphical Representation

A graphical representation of the AOP.

This graphic should list all KEs in sequence, including the MIE (if known) and AO, and the pair-wise relationships (links or KERs) between those KEs.

Handbook Entry

C Authors of AOP

Authors and Affiliations

The names and affiliations of the individual(s)/organisation(s) that created/developed the AOP.

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Point of Contact

The user responsible for managing the AOP entry in the AOP-KB and controlling write access to the page by defining the contributors as described in the next section.  

Handbook Entry


Users with write access to the AOP page. 

Entries in this field are controlled by the Point of Contact.

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This field is used to identify coaches who supported the development of the AOP. Each coach selected must be a registered author.

D Status of an AOP

Author status

Provides users with information concerning how actively the AOP page is being developed, what type of use or input the authors feel comfortable with given the current level of development, and whether it is part of the OECD AOP Development Workplan and has been reviewed and/or endorsed.

  • OECD Status - Tracks the level of review/endorsement the AOP has been subjected to.
  • OECD Project Number - Project number is designated and updated by the OECD.
  • SAAOP Status - Status managed and updated by SAAOP curators.
Handbook Entry

Status Table

Handbook Version: Authors have the option to switch to a newer (but not older) Handbook on the AOP Edit page. OECD Status: For AOPs included on the OECD ESCA AG workplan, ‘OECD status’ tracks the level of review/endorsement of the AOP . This designation is managed and updated by the OECD. OECD Project: Assigned upon acceptance onto OECD ESCA AG workplan. This project ID is managed and updated (if needed) by the OECD.

Date Modified

The date the AOP was last modified is automatically tracked by the AOP-KB. The date modified field can be used to evaluate how actively the page is under development and how recently the version within the AOP-Wiki has been updated compared to any snapshots that were generated.

Handbook Entry

Handbook Version

The current version of the Developer's Handbook will be automatically populated into the Handbook Version field when a new AOP page is created. Authors have the option to switch to a newer (but not older) Handbook version any time thereafter.

E AOP Abstract


A concise and informative summation of the AOP under development that can stand-alone from the AOP page.

The aim is to capture the highlights of the AOP and its potential scientific and regulatory relevance.

Handbook Entry

F AOP Development Strategy


Used to provide background information for AOP reviewers and users that is considered helpful in understanding the biology underlying the AOP and the motivation for its development.

The background should NOT provide an overview of the AOP, its KEs or KERs, which are captured in more detail below.

Handbook Entry


Provides a description of the approaches to the identification, screening and quality assessment of the data relevant to identification of the key events and key event relationships included in the AOP or AOP network.

This information is important as a basis to support the objective/envisaged application of the AOP by the regulatory community and to facilitate the reuse of its components.  Suggested content includes a rationale for and description of the scope and focus of the data search and identification strategy/ies including the nature of preliminary scoping and/or expert input, the overall literature screening strategy and more focused literature surveys to identify additional information (including e.g., key search terms, databases and time period searched, any tools used).

Handbook Entry

H KE and KER Tables


This section is for information that describes the overall AOP. The information described in section 1 is entered on the upper portion of an AOP page within the AOP-Wiki. This is where some background information may be provided, the structure of the AOP is described, and the KEs and KERs are listed.

Handbook Entry

Molecular Initiating Event

An MIE is a specialised KE that represents the beginning (point of interaction between a prototypical stressor and the biological system) of an AOP.

Handbook Entry

Key Events

A measurable event within a specific biological level of organisation.

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Adverse Outcome

An AO is a specialized KE that represents the end (an adverse outcome of regulatory significance) of an AOP.

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Relationships Between Two Key Events

This table summarizes all of the KERs of the AOP and is populated in the AOP-Wiki as KERs are added to the AOP.

Each table entry acts as a link to the individual KER description page.

Handbook Entry

I AOP Networks

Network View

This network graphic is automatically generated based on the information provided in the MIE(s), KEs, AO(s), KERs and Weight of Evidence (WoE) summary tables.

The width of the edges representing the KERs is determined by its WoE confidence level, with thicker lines representing higher degrees of confidence. This network view also shows which KEs are shared with other AOPs.

Handbook Entry

J Prototypical Stressors and Applicability Tables

Prototypical Stressors

A structured data field that can be used to identify one or more “prototypical” stressors that act through this AOP. Prototypical stressors are stressors for which responses at multiple key events have been well documented.

Handbook Entry

Life Stage Applicability

The life stage for which the AOP is known to be applicable.

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Taxonomic Applicability

Latin or common names of a species or broader taxonomic grouping (e.g., class, order, family) can be selected.

In many cases, individual species identified in these structured fields will be those for which the strongest evidence used in constructing the AOP was available.

Handbook Entry

Sex Applicability

The sex for which the AOP is known to be applicable.

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K Overall Assessment of the AOP

Overall Assessment Summary

Addressess the relevant biological domain of applicability (i.e., in terms of taxa, sex, life stage, etc.) and Weight of Evidence (WoE) for the overall AOP as a basis to consider appropriate regulatory application (e.g., priority setting, testing strategies or risk assessment).

Handbook Entry

Biological Domain of Applicability

Addressess the relevant biological domain(s) of applicability in terms of sex, life-stage, taxa, and other aspects of biological context.

Handbook Entry

Essentiality of the Key Events

The essentiality of KEs can only be assessed relative to the impact of manipulation of a given KE (e.g., experimentally blocking or exacerbating the event) on the downstream sequence of KEs defined for the AOP.

Consequently, evidence supporting essentiality is assembled on the AOP page, rather than on the independent KE pages that are meant to stand-alone as modular units without reference to other KEs in the sequence. The nature of experimental evidence that is relevant to assessing essentiality relates to the impact on downstream KEs and the AO if upstream KEs are prevented or modified. This includes:

  • Direct evidence: directly measured experimental support that blocking or preventing a KE prevents or impacts downstream KEs in the pathway in the expected fashion.
  • Indirect evidence: evidence that modulation or attenuation in the magnitude of impact on a specific KE (increased effect or decreased effect) is associated with corresponding changes (increases or decreases) in the magnitude or frequency of one or more downstream KEs.
Handbook Entry

Evidence Assessment

Addressess the biological plausibility, empirical support, and quantitative understanding from each KER in an AOP.

Handbook Entry

Evidence for Prototypical Stressor(s) Identification

Empirical support entails consideration of experimental data in terms of the associations between KEs – namely dose-response concordance and temporal relationships between and across multiple KEs.

It is examined most often in studies of dose-response/incidence and temporal relationships for stressors that impact the pathway at multiple levels of biological organization.

Handbook Entry

Known Modulating Factors

Modulating factors (MFs) may alter the shape of the response-response function that describes the quantitative relationship between two KES, thus having an impact on the progression of the pathway or the severity of the AO.

The evidence supporting the influence of various modulating factors is assembled within the individual KERs.

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Quantitative Considerations

Optional field to provide quantitative weight of evidence descriptors.

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L Other AOP Information

Considerations for Potential Applications of the AOP (optional)

Addressess potential applications of an AOP to support regulatory decision-making.

This may include, for example, possible utility for test guideline development or refinement, development of integrated testing and assessment approaches, development of (Q)SARs / or chemical profilers to facilitate the grouping of chemicals for subsequent read-across, screening level hazard assessments or even risk assessment.

Handbook Entry


List of the literature that was cited for this AOP.

Handbook Entry


For further background and instructions regarding Snapshots, please see the linked Help page.

Comments and Discussion

See here for further instructions on how to comment and contribute to discussion.

View History

The View History button will enable the user to view all the changes that have been made to an AOP. The user can compare old and new versions on the AOP on file. 

Watch list

The Watch List provides a list of individual AOP, KE, KER, or Prototypical Stressor that a user is currently watching, similar to Bookmarks on an internet browser.