API

Event: 947

Key Event Title

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Increase, Early Life Stage Mortality

Short name

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Increase, Early Life Stage Mortality

Biological Context

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Level of Biological Organization
Individual



Key Event Components

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Process Object Action
embryonic lethality increased
mortality increased

Key Event Overview


AOPs Including This Key Event

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AOP Name Role of event in AOP
AHR activation to ELS mortality, via VEGF AdverseOutcome
AhR mediated mortality KeyEvent

Stressors

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Taxonomic Applicability

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Term Scientific Term Evidence Link
Vertebrates Vertebrates High NCBI

Life Stages

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Life stage Evidence
Embryo High
Foetal High
Development High

Sex Applicability

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Term Evidence
Unspecific High

Key Event Description

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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

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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

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


Evidence for Perturbation by Stressor



2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD)

Exposure of embryos to 2,3,7,8-TCDD causes early life stage mortality in all studied species of fishes (Doering et al 2013).

 

 


Regulatory Significance of the Adverse Outcome

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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.


References

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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.