Copper dichromium tetraoxide

Endpoint summary

Justification for classification or non-classification

Refer to the corresponding section of the CuO and Cr2O3 CSRs.

Copper dichromium tetraoxide is highly insoluble and is not classified following exposure by the oral, dermal or inhalation routes.  For risk assessment purposes, it is assumed to have a similar toxicity profile to copper oxide and chromium (III) oxide, two relatively insoluble copper and chromium (III) substances.

With regard to copper, there was no evidence of mutagenic activity in Salmonella typhimurium strains when tested with copper sulphate pentahydrate.  In vivo studies conducted with copper sulphate pentahydrate did not induce micronuclei in the polychromatic erythrocytes of mouse bone marrow.  Copper sulphate pentahydrate also did not induce DNA damage in the rat hepatocyte UDS assay.  It was concluded that copper compounds are not genotoxic.

With regard to trivalent chromium, no evidence of mutagenicity was seen in a guideline-compliant Ames study conducted under GLP using insoluble chromium hydroxide, which shares physical/chemical properties with chromium oxide. Chromium (III) has been shown to interact with genetic materials in acellular systems but generally gave negative results in most standard bacterial assays. In in vitro assays with mammalian cells, chromium (III) compounds have shown some genotoxic potential, especially clastogenicity.  Negative results were seen in a guideline-compliant mouse micronucleus study conducted under GLP using chromium oxide. Negative results have generally been seen with chromium (III) compounds in other animal genotoxicity studies which evaluated mutation/recombination in Drosophila, DNA strand breaks/crosslinks in rats and chromosomal aberrations in rats. It was concluded that trivalent chromium is not genotoxic.

In view of the above it is concluded that copper dichromium tetraoxide does not have mutagenic potential.