Fig. 1.

A. The AOP for Parkinsonian motor deficits is taken as an example to underline one of the characteristics of a qAOP model, mainly understanding the cause and effect in the context of predictive toxicology (https://aopwiki.org/aops/3). Numbers represent the indices of the events in the OECD AOP-Wiki Knowledge Base available at https://aopwiki.org/events/XXX, where xxx is the index in the node. B. A causal diagram representing the linkage between cigarette smoking and lung cancer. C. Scheme for the general process of qAOP model development and application. Depending on the available level of resources, an AOP can be used to generate data or model quantitatively to make predictions and test a hypothesis. D. The causal inference engine was proposed by Judea Pearl as described in the text and is taken from [15].