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Key value for chemical safety assessment

Additional information

IN VITRO BACTERIAL GENE MUTATION

In the key study (Hargitai, 2012) the mutagenic potential of the test material was assessed in an Ames test conducted under GLP conditions and in line with the standardised guidelines OECD 471, EU Method B.13/14 and EPA OPPTS 870.5100. S. typhimurium TA 1535, TA 1537, TA 98, TA 100 and E. coli WP2uvrA were exposed to the test material at concentrations of 5000, 1581, 500, 158.1, 50, 15.81, 5 and 1.581 µg/plate using the plate incorporation method. Positive and solvent controls were run concurrently for comparison.

Under the conditions of the test, the test material did not induce gene mutations by base pair changes or frameshifts in the genome of the strains used, therefore the test material is considered to be non-mutagenic. Cytotoxicity was observed in both S. typhimurium and E. coli at certain concentrations at or above 500 µg/plate, however this was dependant on the strain and the presence or absence of metabolic activation.

 

IN VITRO MAMMALIAN CELL CYTOGENICITY

In the key study (Murata, 2011) the clastogneic potential of the test material was determined in an in vitro mammalian chromosome aberration test with Chinese hamster lung fibroblasts (V79). The study was performed under GLP conditions and according to OECD 473. Two experiments were performed during this study. Experiment 1 was conducted with a short term exposure of 6 hours in the presence and absence of metabolic activation system S9. Experiment 2 was conducted with continuous exposure for either 24 or 48 hours in the absence of metabolic activation. Solvent and positive controls were run concurrently for comparison.

Under the conditions of the test, the frequency of structural and numerical chromosome aberrations was less than 5.0%, determined in test systems exposed under short term (with and without metabolic activation) and continuous exposure (without metabolic activation). Cytotoxicity was observed at concentrations ≥ 1.89 mg/mL under short term exposure, independent of metabolic activation. Under continuous exposure cytotoxicity was also observed at concentrations ≥ 0.945 mg/mL without metabolic activation. Accordingly the test material was considered to be negative for clastogenic potential.

 

IN VITRO MAMMALIAN CELL GENE MUTATION

In the key study (Hargitai, 2013) the mutagenic potential of the test material was determined in anin vitromouse lymphoma assay, conducted under GLP conditions and in line with the standardised guidelines OECD 476 and EU Method B.17.

Cultures of mouse lymphoma L5178Y cells were exposed to the test material at concentrations ranging from 6.25 to 1000 μg/mL, in two assays, both with and without the addition of a rat metabolic activation system (S9 fraction). Assay 1 was performed with two experiments, both with a three hour exposure period; however the first was performed in the presence and the second in the absence of metabolic activation. Assay 2 was performed again with two experiments. The first was performed with metabolic activation and an exposure period of 3 hours, whereas the second experiment was performed without metabolic activation with a 24 hour exposure period. All experiments were conducted with an expression time of 3 days and a selection time of 2 weeks, with trifuorothymidine as the selection agent. Treatment with the test material did not result in a statistically significant increase in mutation frequencies either in the presence or absence of metabolic activation system in the Mouse Lymphoma Assay. The test material was therefore considered to have no mutagenic potential under the conditions of this test.

 


Justification for selection of genetic toxicity endpoint
One single study could not be selected as key, since all three studies are necessary to address this endpoint. The three studies assess different types of in vitro genetic toxicity: bacterial gene mutation, mammalian chromosome aberration and mammalian gene mutation. All three studies were performed under GLP conditions and in accordance with standardised guidelines. The studies have been assigned a reliability score of 1 in line with Klimisch (1997).

Short description of key information:
Ames test: Negative, OECD 471, EU Method B.13/14 and EPA OPPTS 870.5100, Hargitai (2012).
Chromosome aberration assay: Negative, OECD 473, Murata (2011).
Mouse lymphoma assay: Negative, OECD 476 and EU Method B.17, Hargitai (2013).

Endpoint Conclusion: No adverse effect observed (negative)

Justification for classification or non-classification

Based on the submitted in vitro data, testing does not indicate any evidence of genetic toxicity as a result of exposure to the test material. In accordance with criteria for classification as defined in Annex I, Regulation (EC) No. 1272/2008, the test material does not require classification under genetic toxicity.