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Assessment of mechanisms driving non-linear dose-response relationships in genotoxicity testing

Gu�rard, M.; Baum, M.; Bitsch, A.; Eisenbrand, G.; Elhajouji, A.; Epe, B.; Habermeyer, M.; Kaina, B.; Martus, H. J.; Pfuhler, S.; Schmitz, C.; Sutter, A.; Thomas, A. D.; Ziemann, C.; Froetschl, R.


M. Gu�rard

M. Baum

A. Bitsch

G. Eisenbrand

A. Elhajouji

B. Epe

M. Habermeyer

B. Kaina

H. J. Martus

S. Pfuhler

C. Schmitz

A. Sutter

A. D. Thomas

C. Ziemann

R. Froetschl


© 2014 Elsevier B.V. In genetic toxicology, risk assessment has traditionally adopted linear dose-responses for any compound that causes genotoxic effects. Increasing evidence of non-linear dose-responses, however, suggests potential cellular tolerance to low levels of many genotoxicants with diverse modes of action. Such putative non-linear dose-responses need to be substantiated by strong mechanistic data that identifies the mechanisms responsible for the tolerance to low doses. This can be achieved by experimental demonstration of cytoprotective mechanisms and by providing experimental support for the existence of tolerance mechanisms against low dose effects. By highlighting key experiments into low dose mechanisms, this review aims to clarify which mechanistic data are required to support the use of non-linear dose-response models in risk assessment. Such key experiments are presented and discussed for alkylating agents, oxidants, particulate matter, nucleoside analogues, topoisomerase inhibitors and aneugens and exemplify the use of gene knockout models or transgenic models as well as chemical modulators of key effectors of relevant pathways and their impact on dose-response relationships. In vitro studies are particularly valuable to elucidate mechanisms of low-dose protection or lack thereof, while in vivo experiments are most appropriate for deriving a safe dose. In order to evaluate the existence of non-linear dose-response relationships for genotoxicants, we suggest that careful attention should be given to the mode of genotoxic action, relevant biomarkers of exposure, as well as to the existence and impact of potential cytoprotective mechanisms like detoxifying metabolism and DNA repair.


Guérard, M., Baum, M., Bitsch, A., Eisenbrand, G., Elhajouji, A., Epe, B., …Froetschl, R. (2015). Assessment of mechanisms driving non-linear dose-response relationships in genotoxicity testing. Mutation Research - Reviews, 763, 181-201.

Journal Article Type Review
Acceptance Date Nov 26, 2014
Online Publication Date Nov 11, 2015
Publication Date Jan 1, 2015
Journal Mutation Research - Reviews in Mutation Research
Print ISSN 1383-5742
Electronic ISSN 1388-2139
Publisher Elsevier
Peer Reviewed Peer Reviewed
Volume 763
Pages 181-201
Public URL
Publisher URL

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