Chapter 7

Dose-response assessment


In which units can the effect concentration of an environmental sample in in vitro bioassay be expressed when the compounds present in the sample are unknown (and therefore we do not know their concentration)?

Would you rather express toxicity data using the benchmarks doses of a fixed response calculated from a whole dose-response curve, e.g. dose at 10% response (BMD10) or using the NOAEL or LOAEL values? Explain why and what can be the advantages of the chosen approach.

Consider that there is a severe effect of chemical-mediated toxicity observed at cellular and organ level. Will the effect be observed at lower dose at cellular or at organ level?

Is it better to use the term dose or concentration in in vitro bioassays?

Why is it necessary to measure cytotoxicity when performing in vitro bioassays and how can cytotoxic effects influence the results obtained from bioassays? 

How do the in vitro assays performed in antagonistic mode differ from the assays carried out in agonistic mode?

What is REP? Explain what it means if the REP of an individual chemical is 1, <1 or >1?