Nano(geno)toxicity of nanoparticles symposium in association with EEMS at ICEM 2009 meeting

Background:

ECETOC and EEMS (European Environmental Mutagen Society) repeated their successful collaboration in 2009 to organise a symposium and forum on the first day of the 10th International Conference on Environmental Mutagens (ICEM) which took place 21-25 August 2009 in Florence, Italy. The aim of the symposium and forum discussion on the "Genotoxicity of engineered nanomaterials" (ENM) was to review the biological significance of the available information on ENM and discuss approaches to identify and evaluate possible genotoxic effects. Knowledge of the mechanism of genotoxicity should support the rationale of genotoxicity testing of ENM.

Speakers at the symposium explained that the major target organs of ENM exposure are the lung, the central nervous system, and the cardiovascular system. An important point is the physico-chemical characterisation of the test material according to the endpoint studied (e.g. inflammatory response, DNA damages).

Genotoxicity can be the result of a direct interaction with the DNA or indirectly as a consequence of interaction with a non-DNA target such as the spindle apparatus or DNA repair enzymes. Furthermore, it is essential to clarify whether ENM induce primary genotoxicity (elicited by the particles themselves) or cause secondary effects (elicited by the recruited inflammation). For example, although not equivalent measurements, both DNA damage assessed by the Comet assay and micronucleus production are indicators for genotoxicity but as endpoints incapable of differentiating between a primary or secondary mechanism.

Outcome:

The forum expanded on the problems associated with genotoxicity testing of nanomaterials, and elucidated possible genotoxic mechanisms to support improved test strategies. In the ensuing discussion the audience addressed four questions; whether:

1. current OECD tests are appropriate and sufficient
2. ENM found systemically are biologically relevant
3. there is a minimal set of parameters to be reported in a study
4. which ENM material can be used as a reference?

A set of articles based on the symposium and forum presentations will be published in the journal Nanotoxicology.