Matte, nickel

Endpoint summary

Additional information

Nickel matte has a harmonized EU CLP classification. Nickel matte does not carry a classification for mutagenicity in the 1st ATP to the CLP Regulation. Three studies have been identified investigating the mutagenic potential of Ni mattes (BSL 2009a-c). The nickel matte samples tested represented a range of composition with regards to concentrations of constituent substances across the three groups of nickel matte compositions. Read-across within these groups is justified as each composition within each group has the same mineralogy and very similar compositions, with the compositions within each group differing only for classification purposes by the level of cobalt. Since cobalt levels are low (e.g. <=6%) in all compositions, and cobalt does not contribute to the classification of this endpoint, read-across within each group is justified for this endpoint. As nickel matte is considered a UVCB with variable composition, the availability of reliable data on multiple samples can be combined to provide important information regarding the potential of nickel mattes to cause genetic toxicity.

These GLP in vitro mammalian cell gene mutation studies were conducted in accordance with OECD Guideline No. 476, EEC Directive Annex 4E, B 17, and EPA OPPTS 870.5300. The mouse lymphoma cell line L5178Y was used to evaluate the potential for three distinct Ni matte group samples to induce mutations at the thymidine kinase locus, both in the presence and absence of metabolic activation. The selection of the concentrations tested was based on data from the pre-experiments. In all three studies, growth inhibition was observed in experiment I and II with and without metabolic activation. No biologically relevant increase of mutants was found after treatment with the test item (with and without metabolic activation) in experiments I or II. None of the studies demonstrated a dose-response relationship. Additionally, in experiments I and II of each study, colony sizing showed no clastogenic effects induced by the test item under the experimental conditions (with and without metabolic activation). In conclusion, in the described mutagenicity tests under the experimental conditions reported, the three distinct nickel matte group samples were considered to be non-mutagenic in the mouse lymphoma thymidine kinase locus using the cell line L5178Y.

In addition to the above studies, the UVCB classification was calculated by applying the CLP mixture rules based on the classification of the known or worst-case speciation of each constituent and worst-case constituent concentration in the UVCB (i.e. the maximum value of the typical concentration reported by the individual legal entities), using the MeClas tool.  Assessment with the MeClas tool indicated a positive classification for mutagenicity by the mixtures rules calculation for all nickel matte compositions. This classification was driven by nickel subsulphide. However, in vitro mutagenicity test data revealed that samples of all three groups of nickel matte were considered to be non-mutagenic, which is consistent with the CLP lack of classification and overriding the mixtures rules calculation.  Furthermore, bioaccessibility testing showed that nickel matte has very limited solubility in artificial alveolar fluid (See attached CSR section 5.1 and IUCLID section 7.1), indicating its components are not available to act as direct mutagens, onsistent with the lack of mutagenicity found in in vitro studies.

The following information is taken into account for any hazard / risk assessment:

The results from three recently completed GLP in vitro mammalian cell gene mutation studies conducted in accordance with OECD Guideline No. 476 as well as classification of the metal constituents based on mixture toxicity rules and bioaccessibility in biologically relevant fluids support the conclusion that Ni matte is considered to be non-mutagenic and supports the lack of CLP classification for mutagenicity.

Value used for CSA:Genetic toxicity: No adverse effect observed (negative)

Short description of key information:
The results from three recently completed GLP in vitro mammalian cell gene mutation studies conducted in accordance with OECD Guideline No. 476support the conclusion that Ni matte is considered to be non-mutagenic.

Endpoint Conclusion: No adverse effect observed (negative)

Justification for classification or non-classification

Ni matte is not classified for mutagenicity according to the 1^stATP to the CLP Regulation. This is supported by in vitro mutagenicity studies conducted with three different Ni matte types and mixtures calculations that demonstrated none of the samples were mutagenic under the test conditions. This test data overrides the mixtures rules calculation for mutagenicity based on nickel subsulphide content performed with MeClas.

·   See furthermore attached documents:

Please refer to IUCLID section 13 or CSR Appendix I for detailed MeClas printouts with the specified input concentrations and resulting classification. Please visit www.meclas.eu for more information about the tool.