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Event: 947

Key Event Title

A descriptive phrase which defines a discrete biological change that can be measured. More help

Increase, Early Life Stage Mortality

Short name
The KE short name should be a reasonable abbreviation of the KE title and is used in labelling this object throughout the AOP-Wiki. More help
Increase, Early Life Stage Mortality
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Biological Context

Structured terms, selected from a drop-down menu, are used to identify the level of biological organization for each KE. More help
Level of Biological Organization

Key Event Components

The KE, as defined by a set structured ontology terms consisting of a biological process, object, and action with each term originating from one of 14 biological ontologies (Ives, et al., 2017; Biological process describes dynamics of the underlying biological system (e.g., receptor signalling).Biological process describes dynamics of the underlying biological system (e.g., receptor signaling).  The biological object is the subject of the perturbation (e.g., a specific biological receptor that is activated or inhibited). Action represents the direction of perturbation of this system (generally increased or decreased; e.g., ‘decreased’ in the case of a receptor that is inhibited to indicate a decrease in the signaling by that receptor).  Note that when editing Event Components, clicking an existing Event Component from the Suggestions menu will autopopulate these fields, along with their source ID and description.  To clear any fields before submitting the event component, use the 'Clear process,' 'Clear object,' or 'Clear action' buttons.  If a desired term does not exist, a new term request may be made via Term Requests.  Event components may not be edited; to edit an event component, remove the existing event component and create a new one using the terms that you wish to add.  Further information on Event Components and Biological Context may be viewed on the attached pdf. More help
Process Object Action
embryonic lethality increased
mortality increased

Key Event Overview

AOPs Including This Key Event

All of the AOPs that are linked to this KE will automatically be listed in this subsection. This table can be particularly useful for derivation of AOP networks including the KE. Clicking on the name of the AOP will bring you to the individual page for that AOP. More help
AOP Name Role of event in AOP Point of Contact Author Status OECD Status
AHR activation to ELS mortality, via VEGF AdverseOutcome Amani Farhat (send email) Open for citation & comment WPHA/WNT Endorsed
AhR mediated mortality, via COX-2 KeyEvent Markus Hecker (send email) Open for citation & comment WPHA/WNT Endorsed
Ahr mediated early stage mortality via craniofacial malformations AdverseOutcome Prarthana Shankar (send email) Under development: Not open for comment. Do not cite
Ahr mediated early stage mortality via cardiovascular toxicity AdverseOutcome Prarthana Shankar (send email) Under development: Not open for comment. Do not cite

Taxonomic Applicability

Latin or common names of a species or broader taxonomic grouping (e.g., class, order, family) that help to define the biological applicability domain of the KE.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 in relation to this KE. More help
Term Scientific Term Evidence Link
Vertebrates Vertebrates High NCBI

Life Stages

An indication of the the relevant life stage(s) for this KE. More help
Life stage Evidence
Embryo High
Foetal High
Development High

Sex Applicability

An indication of the the relevant sex for this KE. More help
Term Evidence
Unspecific High

Key Event Description

A description of the biological state being observed or measured, the biological compartment in which it is measured, and its general role in the biology should be provided. More help

Increased early life stage mortality refers to an increase in the number of individuals dying in an experimental replicate group or in a population over a specific period of time.

In Birds:

Early life stage mortality occurs at any stage in development prior to birth/hatch and is considered embryolethal.

In Fishes:

Early Life Stage Mortality refers to death prior to yolk sac adsorption and swim-up.

How It Is Measured or Detected

A description of the type(s) of measurements that can be employed to evaluate the KE and the relative level of scientific confidence in those measurements.These can range from citation of specific validated test guidelines, citation of specific methods published in the peer reviewed literature, or outlines of a general protocol or approach (e.g., a protein may be measured by ELISA). Do not provide detailed protocols. More help

In birds it may be identified as failure to hatch or lack of movement within the egg when candled; heartbeat monitors are available for identifying viable avian and reptillian eggs (ex. Avitronic's Buddy monitor). In mammals, stillborn or mummified offspring, or an increased rate of resorptions early in pregnancy are all considered embryolethal, and can be detected using ultra-high frequency ultrasound (30-70 MHz; a.k.a. ultrasound biomicroscopy) (Flores et al. 2014). In fishes, mortality is typically measured by observation. Lack of any heart beat, gill movement, and body movement are typical signs of death used in the evaluation of mortality.

Domain of Applicability

A description of the scientific basis for the indicated domains of applicability and the WoE calls (if provided).  More help

All members of the subphylum vertebrata are susceptible to early life stage death (Weinstein 1999).

Regulatory Significance of the Adverse Outcome

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

Poor early life stage survival is an endpoint of major relevance to environmental regulators, as it is likely to lead to population decline.  Early-life stage, acute and chronic test guidelines have been established by the Organisation for Economic Co-operation and Development (OECD), U.S. Environmental Protection Agency (EPA) and Environment and Climate Change Canada (ECCC), and are currently used in risk assessments to set limits for safe exposures.  Aquatic test guidlines are most prevalent and include OECD210, OECD229, EPA850.1400 and ECCC  EPS 1/RM/28 for fish and OECD241 for frogs.


List of the literature that was cited for this KE description. More help

1. Flores, L.E., Hildebrandt, T.B., Kuhl, A.A., and Drews, B. (2014) Early detection and staging of spontaneous embryo resorption by ultrasound biomicroscopy in murine pregnancy. Reproductive Biology and Endocrinology 12(38). DOI: 10.1186/1477-7827-12-38

2. Weinstein, B. M. (1999). What guides early embryonic blood vessel formation? Dev. Dyn. 215(1), 2-11.

Doering, J.A.; Giesy, J.P.; Wiseman S.; Hecker, M. (2013). Predicting the sensivity of fishes to dioxin-like compounds: possible role of the aryl hydrocarbon receptor (AhR) ligand binding domain. Environmental Science and Pollution Research. 20 (3), 1219-1224.