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Relationship: 2016


A descriptive phrase which clearly defines the two KEs being considered and the sequential relationship between them (i.e., which is upstream, and which is downstream). More help

AchE Inhibition leads to Decrease, Population growth rate

Upstream event
The causing Key Event (KE) in a Key Event Relationship (KER). More help
Downstream event
The responding Key Event (KE) in a Key Event Relationship (KER). More help

Key Event Relationship Overview

The utility of AOPs for regulatory application is defined, to a large extent, by the confidence and precision with which they facilitate extrapolation of data measured at low levels of biological organisation to predicted outcomes at higher levels of organisation and the extent to which they can link biological effect measurements to their specific causes. Within the AOP framework, the predictive relationships that facilitate extrapolation are represented by the KERs. Consequently, the overall WoE for an AOP is a reflection in part, of the level of confidence in the underlying series of KERs it encompasses. Therefore, describing the KERs in an AOP involves assembling and organising the types of information and evidence that defines the scientific basis for inferring the probable change in, or state of, a downstream KE from the known or measured state of an upstream KE. More help

AOPs Referencing Relationship

AOP Name Adjacency Weight of Evidence Quantitative Understanding Point of Contact Author Status OECD Status
Acetylcholinesterase inhibition leading to acute mortality non-adjacent Low Low Cataia Ives (send email) Under Development: Contributions and Comments Welcome Under Development

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 KER.In general, this will be dictated by the more restrictive of the two KEs being linked together by the KER.  More help

Sex Applicability

An indication of the the relevant sex for this KER. More help

Life Stage Applicability

An indication of the the relevant life stage(s) for this KER.  More help

Key Event Relationship Description

Provides a concise overview of the information given below as well as addressing details that aren’t inherent in the description of the KEs themselves. More help
  • AChE inhibition at the individual level may lead to a declining population trajectory.

Evidence Collection Strategy

Include a description of the approach for identification and assembly of the evidence base for the KER.  For evidence identification, include, for example, a description of the sources and dates of information consulted including expert knowledge, databases searched and associated search terms/strings.  Include also a description of study screening criteria and methodology, study quality assessment considerations, the data extraction strategy and links to any repositories/databases of relevant references.Tabular summaries and links to relevant supporting documentation are encouraged, wherever possible. More help

Evidence Supporting this KER

Addresses the scientific evidence supporting KERs in an AOP setting the stage for overall assessment of the AOP. More help
Biological Plausibility
Addresses the biological rationale for a connection between KEupstream and KEdownstream.  This field can also incorporate additional mechanistic details that help inform the relationship between KEs, this is useful when it is not practical/pragmatic to represent these details as separate KEs due to the difficulty or relative infrequency with which it is likely to be measured.   More help
  • Wildlife studies including fish and birds have shown that exposure to AchE inhibitors can lead to physiological changes and behavioral alterations, which can make individuals more vulnerable to prey. It is biologically plausible that decreased survival and reproduction could decrease the population trajectory, if the scale of the changes were significant.
Uncertainties and Inconsistencies
Addresses inconsistencies or uncertainties in the relationship including the identification of experimental details that may explain apparent deviations from the expected patterns of concordance. More help
  • In bluegill and largemouth bass, the principal mode of exposure was unclear. The relative uptake from pesticide-treated insects versus direct uptake from water was not quantifiable, although the data suggest that fish more readily metabolize insecticides introduced via diet than via oral exposure (Macek 1972).

  • Fish appeared to be more sensitive to exposure at a higher water temperature (Macek 1972).

Known modulating factors

This table captures specific information on the MF, its properties, how it affects the KER and respective references.1.) What is the modulating factor? Name the factor for which solid evidence exists that it influences this KER. Examples: age, sex, genotype, diet 2.) Details of this modulating factor. Specify which features of this MF are relevant for this KER. Examples: a specific age range or a specific biological age (defined by...); a specific gene mutation or variant, a specific nutrient (deficit or surplus); a sex-specific homone; a certain threshold value (e.g. serum levels of a chemical above...) 3.) Description of how this modulating factor affects this KER. Describe the provable modification of the KER (also quantitatively, if known). Examples: increase or decrease of the magnitude of effect (by a factor of...); change of the time-course of the effect (onset delay by...); alteration of the probability of the effect; increase or decrease of the sensitivity of the downstream effect (by a factor of...) 4.) Provision of supporting scientific evidence for an effect of this MF on this KER. Give a list of references.  More help
Response-response Relationship
Provides sources of data that define the response-response relationships between the KEs.  More help
Information regarding the approximate time-scale of the changes in KEdownstream relative to changes in KEupstream (i.e., do effects on KEdownstream lag those on KEupstream by seconds, minutes, hours, or days?). More help
Known Feedforward/Feedback loops influencing this KER
Define whether there are known positive or negative feedback mechanisms involved and what is understood about their time-course and homeostatic limits. More help

Domain of Applicability

A free-text section of the KER description that the developers can use to explain their rationale for the taxonomic, life stage, or sex applicability structured terms. More help
  • Fish and aquatic invertebrates exposed to OP insecticides showing high AChE inhibition as compared to fish from untreated ponds, did not recover normal AChE activity for 28 days following exposure (Macek 1972).

  • Birds exposed to OP pesticides display behavioral changes (Eng 2017).

  • OP toxicity in birds and mammals is determined by multiple factors. Varying sensitivity within taxa is related to chemical affinity for binding with brain AChE, ability of hepatic and brain tissue to metabolize these compounds and activate latent inhibitors, and the affinity of parent compounds and their metabolites for nontarget esterases (Grue 1997).


List of the literature that was cited for this KER description. More help
  • Banaee,M., Sureda, A. Mirvaghefi, A.R. and K. Ahmadi. 2011. Effects of Diazinon on Biochemical Parameters of Blood in Rainbow Trout  (Oncorhynchus mykiss). Pestic. Biochem. Physiol. 99(1): 1-6.

  • Calisi, A., Lionetto, M.G., Schettino, T. 2011. Biomarker response in the earthworm Lumbricus terrestris exposed to chemical pollutants. Science of the Total Environment. 409, 4456-4464.

  • Eng, M.L., Stutchbury, B.J.M. & Morrissey, C.A. 2017. Imidacloprid and chlorpyrifos insecticides impair migratory ability in a seed-eating songbird. Sci Rep 7, 15176.

  • Grue, C.E., Gibert, P.L., Seeley, M.E. 1997. Neurophysiological and Behavioral Changes in Non-Target Wildlife Exposed to Organophosphate and Carbamate Pesticides: Thermoregulation, Food Consumption, and Reproduction. Amer. Zool., 37:369-388.

  • Jarvinen AW, Nordling BR, Henry ME. 1983. Chronic toxicity of dursban (chlorpyrifos) to the fathead minnow (Pimephales promelas) and the resultant acetylcholinesterase inhibition. Ecotoxicol Environ Saf 7:423–434.

  • Khalil,F., I.J. Kang, S. Undap, R. Tasmin, X. Qiu, Y. Shimasaki, and Y. Oshima. 2013. Alterations in Social Behavior of Japanese Medaka (Oryzias latipes) in Response to Sublethal Chlorpyrifos Exposure. Chemosphere. 92(1): 125-130.

  • Macek, K.J., Walsh, D.F., Hogan, J.W., Holz, D.D. 1972. Toxicity of the Insecticide Dursban to Fish and Aquatic Invertebrates in Ponds. Trans. Am. Fish. Soc., 101(3): 420-427.

  • Pant, R., Katiyar, S.K. 1983. Effect of malathion and acetylcholine on the developing larvae of Philosamia ricini (Lepidoptera: Saturniidae). J. Biosci. 5(1), 89-95.

  • Yen,J., S. Donerly, E.D. Levin, and E.A. Linney. 2011. Differential Acetylcholinesterase Inhibition of Chlorpyrifos, Diazinon and Parathion in Larval Zebrafish. Neurotoxicol. Teratol. 33(6): 735-741.