A note of caution: the threshold of toxicological concern (TTC) is unsuited as a decision rule for deciding whether mixture risk assessment is necessary

Department for Biological and Environmental Sciences, University of Gothenburg, Gothenburg, Sweden
DOI
10.7287/peerj.preprints.526v1
Subject Areas
Environmental Sciences
Keywords
TTC, threshold of toxicological concern, chemical mixtures, risk assessment
Copyright
© 2014 Backhaus
Licence
This is an open access article distributed under the terms of the Creative Commons Attribution License, which permits unrestricted use, distribution, reproduction and adaptation in any medium and for any purpose provided that it is properly attributed. For attribution, the original author(s), title, publication source (PeerJ PrePrints) and either DOI or URL of the article must be cited.
Cite this article
Backhaus T. 2014. A note of caution: the threshold of toxicological concern (TTC) is unsuited as a decision rule for deciding whether mixture risk assessment is necessary. PeerJ PrePrints 2:e526v1

Abstract

The threshold of toxicological concern has been suggested as a decision rule on whether a mixture risk assessment is required. According to the recent opinion on mixture toxicity, published by the EU scientific committees, mixture effects are not to be expected, if the mixture components do not share the same mode or mechanism of action and are present at or below their individual TTCs. This, however, ignores the statistical error propagation that is encountered when handling multi-component chemical mixtures, which results in a huge probability that one or more mixture components are de facto more toxic than estimated by the corresponding TTC. It is hence argued that the TTC is a valuable tool to bridge data gaps in case experimental toxicity data are missing, but it is unsuited without further refinement as a decision criterion on whether a mixture assessment is needed in a given exposure scenario.

Author Comment

This is a preprint version of a manuscript submitted to a peer-reviewed journal.