Copper(2+) tetrafluoroborate(1-)

Endpoint summary

Additional information

Reverse mutation assay

An Ames test with Salmonella typhimurium strains TA98, TA100, TA1535, TA1537 and TA1538 and Escherichia coli strain WP2uvrA was available for tetrafluoroboric acid (42% aqueous solution) (Shimizu, 1985). The study was conducted according to the Guidelines of the Japanese Ministry of Labour. The strains were treated with test concentrations ranging from 1 to 5000 μg/plate, both in the presence and absence of metabolic activation. No increased number of revertants was observed in any case. Based on the results, the substance was concluded to give negative results in the Ames test.

No in vitro cytogenicity and gene mutation studies in mammalian cells are available for tetrafluoroboric acid (HBF4). However, such studies are available for potassium tetrafluoroborate (KBF4), a structural analogue of HBF4. As the toxicity of these substances is expected to be driven by the tetrafluoroborate anions formed upon dissociation, the toxicity of HBF4 and KBF4 is considered to be similar (except for the likely corrosive effects of HBF4 resulting from its strong acidity). Therefore, information from the structural analogue KBF4 was used to determine the possible genotoxic effects of HBF4 to mammalian cells.

Gene mutation assay

In a GLP compliant gene mutation test performed according to OECD guideline 476, potassium tetrafluoroborate was examined for its potential to induce gene mutations at the TK-locus of cultured mouse lymphoma L5178Y cells, in both the absence and the presence of a metabolic activation system (S9-mix) (TNO Triskelion BV, 2012). One test was conducted. In this test 6 duplicate cultures were treated for 24 hours and 4 hours in the absence and presence of S9-mix, respectively. The test substance was dissolved in dimethylsuphoxide (DMSO). The highest concentration tested and evaluated for mutagenicity was 10 mmol/L. The test substance was slightly toxic to the cells in the absence of S9 -mix. A slight decrease by 24% of the relative growth (RTG) was observed at the highest dose of 10 mmol/L. In the presence of S9 -mix no cytotoxicity was observed. In both the absence and presence of S9-mix no increase in mutant frequency was observed at any test substance concentration evaluated. All data were within the range of the negative control and the historical background. Methyl methanesulphonate (MMS) and 3-methylcholanthrene (MCA) were used as positive control substances in the absence and presence of the S9-mix, respectively; DMSO served as negative control. The negative controls were within historical background ranges and treatment with the positive control yielded the expected significant increase in mutant frequency compared to the negative controls. It is concluded that under the conditions used in this study, the test substance potassium tetrafluoroborate is not mutagenic at the TK-locus of mouse lymphoma L5178Y cells in both the absence and presence of metabolic activation (S9-mix).

Micronucleus test

In a GLP-compliant micronucleus test, performed according to OECD Guideline 487, potassium tetrafluoroborate was examined for its potential to induce micronuclei in cultured binucleated human lymphocytes, in both the absence and presence of a metabolic activation system (S9 -mix) (TNO Triskelion BV, 2012). Two independent in vitro micronucleus tests were conducted for which blood was obtained from two different donors. Dimethylsulfoxide (DMSO) was used as solvent for the test substance. Dose levels ranging from 2.5 to 1260 μg/mL were tested as final concentrations in the culture medium. Cytotoxicity was calculated from the Cytokinesis-Block Proliferation Index (CBPI). In the first test, in the presence and absence of metabolic activation (S9-mix) the treatment/recovery time was 4/20 hours (pulse treatment). In the second test, in the absence of metabolic activation, the treatment/recovery time was 20/28 hours (continuous treatment group). In the first test, in the presence of metabolic activation, a trend towards slightly decreased CBPI-values was observed at all dose levels. In the absence of metabolic activation, no cytotoxicity was observed. In the pulse treatment test, analysis of micronuclei formation was carried out at three dose levels (1260, 630 and 315 μg/mL), in the cultures of the solvent control and in the cultures of the positive controls. In the second test, no cytotoxicity was observed at any of the dose levels analysed. In the continuous treatment group, analysis of micronuclei formation was carried out in the cultures of three dose levels (1260, 1000 and 800 μg/mL) of the test substance, the cultures of the solvent control and the cultures of the positive controls. In both the first and the second test, the negative controls were within the historical data. Treatment with the positive controls, cyclophosphamide, vinblastine sulphate and mitomycin C, resulted in statistically significant increases in the numbers of binucleated cells containing micronuclei, when compared to the numbers observed in the cultures treated with the solvent control. This demonstrates the validity of the study. In both the first and second test, the test substance did not cause a significant increase in the number of binucleated cells containing micronuclei, at any of the dose levels analysed, when compared to the numbers found in the concurrent negative control. From the results obtained in the first and second in vitro micronucleus test it is concluded that, under the conditions used in this study, the test substance potassium tetrafluoroborate was not clastogenic and/or aneugenic to cultured human lymphocytes.

Short description of key information:

HBF4 gave negative results in the reverse mutation assay both with and without metabolic activation. The structural analogue KBF4 gave negative results in the in vitro gene mutation assay, and the in vitro micronucleus test both with and without metabolic activation.

Endpoint Conclusion: No adverse effect observed (negative)

Justification for classification or non-classification

Based on the available in vitro genotoxicity studies of HBF4 and KBF4, a structural analogue of HBF4, the test substance does not need to be classified for genotoxicity according to Directive 67/548/EEC and according to the EU Classification, Labelling and Packaging of Substances and Mixtures (CLP) Regulation (EC) No. 1272/2008