Chapter 9

In vitro assays for the risk assessment of chemicals


Explain the difference of a specifically and a selectively acting chemical in an in vitro assay using the specificity ratio SRcytotoxicity and the SRbaseline.

In the Excel sheet “9A2 Exercise TR” you find algal toxicity data from Glauch and Escher (2020), 10.1002/etc.4873. You can find the experimentally determined EC1024h, growth and the QSAR EC1024h, growth values of several test chemicals in the combined algae test.

a)    Please calculate the toxic ratio (TR24h, growth) for all chemicals.

b)    Decide whether the chemical is a baseline toxicant or showing specific toxicity based on these results.

9A2Exercise TR.xlsx