An AOP can be viewed as a sequence of events commencing with a molecular initiating event and progressing through a series of intermediate steps, to culminate in an adverse outcome. Two years after the launch of its knowledge base, the OECD has endorsed and published the first five AOPs, which are as follows:

  • protein alkylation leading to liver fibrosis
  • alkylation of DNA in male pre-meiotic germ cells leading to heritable mutations
  • aromatase inhibition leading to reproductive dysfunction in fish
  • chronic binding of antagonist to N-methyl-D-aspartate receptors (NMDARs) during brain development, inducing impairment of learning and memory abilities
  • binding of agonists to ionotropic glutamate receptors in adult brain leading to excitotoxicity that mediates neuronal cell death, contributing to learning and memory impairment

The OECD has also provided a users’ handbook to aid in developing and assessing AOPs.

Organization for Economic Co-operation and Development (2016). OECD Series on Adverse Outcome Pathways. Available at:


The above items were taken from the November 2016 issue of Toxicology and Regulatory News which is sent automatically to members of bibra (click here)

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