The Organisation for Economic Co-operation and Development recently released three new working papers on Adverse Outcome Pathways (AOPs). AOPs describe a sequential chain of causally linked events at different levels of biological organisation that lead to an adverse health or ecotoxicological effect. They are the central element of a toxicological knowledge framework that supports chemical risk assessment based on mechanistic reasoning. The first AOP details the linkage between binding and activation of androgen receptors in females and reproductive dysfunction in repeat-spawning fish. A second describes the association between the inhibition of complex I of the mitochondrial respiratory chain and motor deficit symptoms typical for parkinsonian disorders. A third AOP suggests chronic binding of antagonist to N-methyl-D-aspartate receptors during brain development may lead to neurodegeneration with impairment in learning and memory in aging. More info.