Table 2.

Characterisation of five probabilistic models that use the Bayesian network approach and an AOP construct

Model purpose	Adverse outcome	Mechanistic knowledge and associated data								Quantitative approach	Regulatory applicability	References
		OECD AOP-Wiki a	Type of AOPd	Type of chemical model applied to	Data type	Adjacent KERs	Biological level(s)	D/C–Re	T–Rf
The risk posed by pesticides and environmental stressors to population size of Chinook salmon	Alteration of population dynamics	Nob	AOPN	Mixtures	In vitro experimental data, literature data, AOP construction, environmental factors, population characteristics	√	Molecular, cellular, organ, organism, population	√	√	Bayesian Network-Relative Risk type of model	Ecological risk assessment	Chu (2018)
Effects on reproduction of Lemna minor (duckweed)	Reduced number of fronds	AOP ID 245	LAOP	Single chemical	In vitro experimental data, AOP construction	√	Molecular, cellular, organism	√	–	Bayesian network type of model (discrete states as three intervals)	Ecological risk assessment	Moe et al. (2018)
Toxicity of silver nanoparticles, linking MIE to the AO	Reproduction failure	AOP ID 207	LAOP	Nanoparticles	In vitro experimental data, literature data, AOP construction	√	Molecular, cellular, organ, organism	√	√	Bayesian network type of model (discrete states as yes/no, and decrease/stable/increase), Boostrapping	Ecological risk assessment	Jeong et al. (2018)
Occurrence of steatosis under different chemical exposures	Hepatic steatosis	Noc	AOPN	Mixtures	Expert judgment, literature data, AOP construction	√	Molecular, cellular, tissue, organ	√	–	Bayesian network type of model (discrete states as active or inactive)	Human health risk assessment	Burgoon et al. (2020) and Perkins et al. (2019a)
Comparison between probabilistic and mechanistic approaches	Nephron attrition leading to chronic kidney disease	AOP ID 284	LAOP	Single chemical	In vitro experimental data on human RPTEC/TERT1 cells, AOP construction	√	Molecular, cellular, tissue, organ	√	√	Dynamic Bayesian network type of model	Human health risk assessment	Zgheib et al. (2019)g

^aNumbers represent the indices (XXX) of the AOP in the AOP-Wiki available at https://aopwiki.org/aops/XXX

^bModel follows an AOP structure, the MIE (ID 12) can be found in the AOP-Wiki, however the AOP itself is not yet published

^cModel is included in the AOPXplorer tool (https://apps.cytoscape.org/apps/aopxplorer) as it follows the structure of an AOP network

^dLinear AOP (LAOP), AOP Network (AOPN)

^eDose/Concentration–Response (D/C–R)

^fTime–Response (T–R) describing the time-course behaviour

^gModel represents a combination of both probabilistic and mechanistic approaches