Adverse Outcome Pathways (AOP) are becoming a fashionable term in the toxicological risk assessment stage. But what does AOP mean? Most important, to what purpose we could use AOPs?

AOP describe the chain of events from the first interaction of any chemical with a molecular target to an adverse outcome; this could be either an effect detected in regulatory toxicity testing, or a health disorder observed in humans, domestic animals or wildlife. Therefore, the ambition of the AOPs conceptual framework is to build a new paradigm of toxicological testing, based on the keywords ‘relevance’ and ‘predictivity’. Any chemical triggering an upstream molecular/cellular event with sufficient intensity is flagged as a chemical able to perturb adversely a physiological pathway, and therefore induce a certain kind of toxicity. Definitely, a facinating aspect of AOP are the potential cross-talk and cross-fertilization between toxicology and biomedicine, a field which is making impressive steps forward. But, how AOP can, in practice, improve oxicity testing and toxicological risk assessment?

The key learning objective of the education course on AOP within the 46^th ETS Conference is to illustrate strengths, opportunities, limitations and uncertainties of the use of AOP, based on practical experiences in three key areas of the risk assessment of chemical substances, namely: pesticides, endocrine disrupting chemicals and pharmaceuticals.