Registration Dossier

Toxicological information

Carcinogenicity

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Description of key information

Key value for chemical safety assessment

Additional information

All relevant and available information on intrinsic properties of MWCNT are cited in chapter 7 of the IUCLID. Although a large number of studies on the toxicity of MWCNTs have recently been published, clear characterization of the test materials including sample preparation which are quite essential for ensuring reproducibility and reliability in the toxicity test using suspension, in vivo and in vitro methods, is often missing. Importantly, modifications of some specific characteristics of the MWCNT tested such as variations in particle size distribution or length might give rise to differences in the toxicological profile. 

Toxic effects of different MWCNTs seem to depend on the form (length) and physico-chemical properties (metal content, aggregation/agglomeration, surface chemistry, and functionalisation). Thus for the time being, a case-by-case approach would be appropriate and the hazard assessment for MWCNT meeting the form described in section 4.5 is based solely on the information collected with this MWCNT. That is the reason why a comprehensive documentation in the IUCLID dossier and the chemical safety report involved automatically is restricted to all available and relevant data on the MWCNT meeting the form described in section 4.5 of the IUCLID dossier. That means on the other hand that the values used for the risk assessment exercise should not be used in general for all MWCNTs or CNTs, as the results obtained with one particular type of MWCNTs may not necessarily be relevant for other CNTs with other dimensions and properties

In addition the information on MWCNT not meeting the form described in section 4.5 of the IUCLID dossier (the differences can be tracked back to the original papers or because in others the characterization of the materials was unclear or inclomplete) is also included in the IUCLID dossier but the entries are restricted to the information on data source to give a quick overview of all available data.

 

The study published by Muller (2009) using intraperitoneal exposure was conducted to investigate whether the test substance meeting the form described in section 4.5 has the capacity to elicit comparable toxicity to other pathogenic fibres such as asbestos through alterations in mesothelium histopathology. The test substance did not induce mesotheliomas and the incidence of (peritoneal) tumours other than mesotheliomas was not significantly increased in the MWCNT treated groups. In contrast crocidolite induced a clear carcinogenic response.

Additional info are reported under section 13.2 (other assessment report - Nanocyl position on IARC statement).

Justification for classification or non-classification

No classification requiredaccording to EU-Directive 67/548/EEC, Annex VI.

No classification required according to Regulation (EC) No 1272/2008, Annex I.