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Key value for chemical safety assessment

Additional information

in vitro:

Ames test:

In a GLP-compliant reverse gene mutation assay according to OECD TG 471/472 (BASF AG, 1999), Salmonella typhimurium strains TA1535, TA1537, TA98, TA100 and Escherichia coli strain WP2 uvrA were exposed to 0, 20, 100, 500, 2500 and 5000 ug/plate 3-Hexyne-2,5 -diol (vehicle: water) in a standard plate test in agar (SPT) or in a preincubation test (PIT). Plate assays were performed in triplicate in the presence and absence of mammalian metabolic activation (S9-mix) for each tester strain. Sterility controls were also included for each test strain. No increase in the number of his+ or trp+ revertants was observed in the standard plate test or in the preincubation test either without S-9 mix or after the addition of a metabolizing system for every tester strain. Obtained data were within the range of the historical negative control data or sometimes decreased due to bacteriotoxicity occurred at concentrations from about 500- 2500 µg/plate onward depending on the tester strain. The positive controls induced the appropriate responses in the corresponding strains and were like the negative vehicle controls within the range of the corresponding historical control data. The sterility controls showed no growth. No precipitation of the test substance was found. Thus, 3 -Hexyne-2,5 -diol was regarded as not mutagenic in the Ames test (Salmonella typhimurium/Escherichia coli reverse mutation assay) under the given experimental conditions.

Chromosome aberration test:

The test item 3-Hexyne-2,5-diol, dissolved in deionised water, was assessed for its potential to induce structural chromosome aberrations in V79 cells of the Chinese hamster in vitro according to OECD TG 473 (Harlan CCR, 2012). Assays were performed in duplicates in the presence and absence of a metabolic activation system (S9 -mix). V79 cells were exposed to 5 to 1270 µg/ mL of the test item for 4h with a recovery period of 14h. 2.5h prior to cell harvest, Colcemid (0.2 µg/mL) was added to the culture medium. Cell number and mitotic index were used as an indicator for cytotoxicity. Breaks, fragments, deletions, exchanges, and chromosome disintegrations were recorded as structural chromosome aberrations. Without metabolic activation, cytotoxicity could be observed at 158.8 µg/mL up to the highest applied concentration. In the presence of S9- mix, cytotoxicity occurred at 600 µg/mL and above. No increase in the number of chromosome aberrations could be observed in any test item concentration up to 79.4 µg/mL without metabolic activation. The vehicle control was within the range of the historical negative control data. Chromosome aberrations could be observed in cells exposed to 158.8 µg/mL and above in the presence of S9 - mix. No relevant increase in polyploid and endomitotic metaphases was found after treatment with the test item as compared to the frequencies of the control cultures. The positive controls induced the number of chromosome aberrations in the range of the corresponding historical control data. Thus, under experimental conditions, 3 -Hexyne-2,5 -diol induced structural chromosomal aberrations in V79 cells of the Chinese hamster in vitro in the presence of metabolic activation when tested up to cytotoxic concentrations.

HPRT:

The study was performed to investigate the potential of 3-Hexyne-2,5-diol to induce gene mutations at the HPRT locus in V79 cells of the Chinese hamster. The assay was performed in two independent experiments, using two parallel cultures each. The first main experiment was performed with and without liver microsomal activation and a treatment period of 4 hours. The second experiment was performed with a treatment time of 4 hours with and 24 hours without metabolic activation. The highest concentration of the pre-experiment (1270 μg/mL) was chosen with regard to the molar concentration of about 10 mM and the purity (90 %, preliminary information at the start of the experiment). The concentration range of the main experiments was limited by cytotoxic effects of the test item. The test item was dissolved in water. No precipitation of the test item was observed up to the maximum concentration of all experiments. Relevant cytotoxic effects indicated by a relative cloning efficiency for cell density below 50% in both parallel cultures occurred in the first experiment at 40.0 μg/mL and above without metabolic activation and at 640 μg/mL and above with metabolic activation. In the second experiment strong cytotoxic effects occurred at 40.0 μg/mL and above without metabolic activation and at 700 μg/mL and above with metabolic activation. The recommended cytotoxic range of approximately 10-20% relative cloning efficiency for relative cell density was covered with and without metabolic activation. No relevant and reproducible increase in mutant colony numbers/106 cells was observed in the main experiments up to the maximum concentration. In experiment II the mutant frequency exceeded the historical range of solvent controls at 40.0 μg/mL (both cultures) and 60.0 μg/mL (second culture) without metabolic activation. However, the induction factor did not exceed the threshold of three times the corresponding solvent control at any concentration and statistical analysis showed that there was no dose dependent increase. Therefore, the increases were judged as biologically irrelevant. A linear regression analysis (least squares) was performed to assess a possible dose dependent increase of mutant frequency. A single significant dose dependent trend of the mutation frequency indicated by a probability value of <0.05 was determined in the first experiment at culture I without metabolic activation. However, the trend was judged as biologically irrelevant since the mutation frequency did neither exceed the threshold described above nor the historical range of solvent controls. In both experiments of this study (with and without S9 mix) the range of the solvent controls was from 7.0 up to 44.2 mutants per 106 cells; the range of the groups treated with the test item was from 4.8 up to 71.7 mutants per 106 cells. The highest solvent control in the absence of S9 mix in experiment II, culture II (40.5 colonies per 106 cells) slightly exceeded the historical range of solvent control (2.6 – 40.3 colonies per 106 cells). However, this effect was judged as irrelevant since it is very minor and the corresponding solvent control of the respective parallel culture remained well within the range of historical controls. EMS (150 μg/mL) and DMBA (1.1 μg/mL) were used as positive controls and showed a distinct increase in induced mutant colonies. In conclusion it can be stated that under the experimental conditions reported the test item did not induce gene mutations at the HPRT locus in V79 cells. Therefore, 3-Hexyne-2,5-diol is considered to be non-mutagenic in this HPRT assay.

in vivo:

In a NMRI mouse bone marrow micronucleus assay (BASF SE, 2012), 5 males/dose were treated orally once with 3 -Hexyne-2,5 -diol at doses of 0, 25, 50 and 100 mg/kg bw. As vehicle control, male mice were administered merely the vehicle, deionized water, by the same route and in the same volume as the animals of the dose groups, which gave frequencies of micronucleated polychromatic erythrocytes within the historical vehicle control data range. Both positive control substances, cyclophosphamide for clastogenicity and vincristine sulfate for spindle poison effects, led to the expected increase in the rate of polychromatic erythrocytes containing small or large micronuclei. No relevant inhibition of erythropoiesis determined from the ratio of polychromatic to normochromatic erythrocytes was detected after test substance administration. According to the results of this study, the single oral administration of 3-Hexyne-2,5-diol did not lead to any biologically relevant increase in the number of polychromatic erythrocytes containing micronuclei. The values obtained were close to the concurrent vehicle control data values and clearly within the laboratory’s historical negative control data range (0.0 – 3.0 ‰micronucleated PCEs).


Short description of key information:
3-Hexyne-2,5-diol was negative in the Ames test with and without metabolic activation. The test item did not induce gene mutations at the HPRT locus in V79 cells. In the chromosome aberration test in the presence of S9 mix a concentration- dependent increase of chromosomal aberrations was observed when tested up to cytotoxic concentrations. According to the results of an in vivo MNT, the single oral administration of 3-Hexyne-2,5-diol did not lead to any biologically relevant increase in the number of polychromatic erythrocytes containing micronuclei.

Endpoint Conclusion: No adverse effect observed (negative)

Justification for classification or non-classification

Based on the available data, the test item was not classified and labelled since the criteria according to Directive 67/548/EEC (DSD) and to Regulation (EC) No 1272/2008 (CLP) are not met.