What are AOPs and how do they work in environmental risk assessment?

Schirmer: The idea is to understand how chemicals exert toxic effects on living organisms. AOPs describe events that lead to toxicity, starting at the molecular level and continuing to the cell, tissue and whole organism level, similar to a domino effect. The final adverse outcome is traditionally measured in animal experiments, for example when a fish can no longer grow, cannot reproduce or even dies. But how did this outcome emerge? We should be able to measure some of these events in cultured cells – we just have to find the right combination that can accurately predict the end result. This is our starting point. Our hypothesis is that we can measure relevant AOPs using cultured fish cells, called cell lines. The measured data will then flow into a computer model, so that in the future it will be sufficient to observe these processes in cell cultures in order to calculate the effect on an organism, in our case fish, without having to carry out animal experiments.
 

You have already established tests that assess the effects of chemicals on fish cells instead of on fish. The AOP tests are a further development of this. Why is this needed?

Fischer: Yes, aQuaTox-Solutions has a number of tests with fish cell cultures in its portfolio, which we offer to the chemical industry, environmental authorities or fish food manufacturers as an alternative to conventional fish tests for risk assessment. A pioneer of these fish cell tests is the so-called RTgill-W1 cell line test for determining acute fish toxicity, which was developed by Eawag and now holds both ISO and OECD certification. However, as is the case with animal testing, with most of these tests, we do not look at the pathways of toxicity, but simply measure the end result, for example cell survival or growth. By adding AOPs to our toolbox, we are aiming for an even better resolution of chemical effects and thus even more sensitive and broadly applicable tests.