Chapter 9

In vitro assays for the risk assessment of chemicals

In the Excel sheet “9E1Exercise Dosing” you can find the physicochemical properties of the three chemicals caffeine, bisphenol A and benzo(a)pyrene.
You should test all three chemicals in the AREc32 and the PPARγ bioassay as single chemicals.

a)    What must be taken into account for the dosing of the chemicals?

b)    Calculate the solubility in the bioassay media for the AREc32 and the PPARγ bioassay using the given equations.

c)    Calculate the concentration (Cnom) that must be dosed to reach baseline toxicity.

d)    Are there any possibilities of what you can do if baseline toxicity cannot be achieved with the maximum soluble concentration?

9E1Exercise Dosing.xlsx

One of the major arguments against in vitro bioassays using immortal stably transfected cell lines is that they are not metabolically active and therefore provide no realistic image of the toxicokinetic processes in an organism. Is there a way to overcome this limitation?

We learnt in Chapter 9 that there is a difference between nominal exposure and what the cells really see. However, in all other chapters, where in vitro assays are used as bioanalytical tools for measuring mixture effects of chemicals extracted from water and other matrices, we are not even touching this question. Is all that we have been doing wrong?