Threshold of Toxicological Concern (TTC) and Mixture Effects of Chemicals: Threshold of Toxicological Concern (TTC) og Blandingseffekter

Henrik Wennermark

Studenteropgave: Semesterprojekt


The threshold of toxicological concern (TTC) has been proposed as a novel tool in the risk assessment of chemicals, which based on knowledge of chemical structure, can set safe-levels without the necessity of performing expensive and time consuming animal toxicity experiments. However, questions have been raised whether the TTC approach, in a sufficient manner, are capable of setting safe thresholds in the context of chemicals mixture effects. This is the subject for this project. The current project assess whether there truly exists zero-effect thresholds for chemicals, the existence of mixture effects at low, human relevant concentrations/ levels and the character of these effects, by searching the current scientific literature in the field. The findings in the present study are that the currently used thresholds of toxicity (NO(A)EL(C) values), at least for endocrine disruptors, are not true zero-effect levels; mixture effects of chemicals at low concentration exists for chemicals of similar mode-of-action (MOA), however, for chemicals with different MOA, mixture effects are uncertain; synergistic effects at low concentrations are probably seldom. The study concludes that TTC, based on the presently suggested use, and due to fundamental issues are not capable of, in a sufficient manner to protect human beings from chemicals mixture effects.

UddannelserTekSam - miljøplanlægning, (Bachelor/kandidatuddannelse) Bachelor el. kandidat
Udgivelsesdato16 jan. 2014
VejledereKristian Syberg


  • Mixture Effects
  • Threshold of Toxicological Concern