Registration Dossier

Administrative data

Key value for chemical safety assessment

Additional information

Procedure and observations

Mutagenicity of the test item was examined in several Ames tests. In five non-GLP, non-guideline studies the material, dissolved in DMSO, was tested in 3 -5 Salmonella strains in presence and absence of a metabolic activation system at concentrations up to 8000 microgramm/0.1 ml; cytotoxicity and an independent repeat experiment was always included. Precipitation of the test item was observed from 225 microgramm/ 0.1 ml onward. Mutagenicity was detected in two of the five assays at precipitating concentrations.

Furthermore, Ames tests according GLP and OECD guideline 471 were performed using Salmonella and E. coli strains. The assays were performed in independent experiments in presence and absence of a metabolic activation system at concentrations up to 5000 microgramm/plate. Slight cytotoxicity was observed at the top dose of 5000 microgramm/plate. Mutagenicity was recorded in one of the four assays in Samonella strains in a dose dependend manner.

Next to the in vitro assays, two in vivo tests were conducted to examine the genotoxic potential of the test item.

At first, the substance was assessed for its potential to induce chromosomal damage (clastogenicity) or spindle poison effects (aneugenic activity) in NMRI mice using the micronucleus test method. For this purpose, the test substance, suspended in corn oil, was administered once orally to male animals at dose levels of 500 mg/kg, 1 000 mg/kg and 2 000 mg/kg body weight in a volume of 10 mL/kg body weight in each case. The animals were sacrificed and the bone marrow of the two femora was prepared 24 and 48 hours after administration in the highest dose group of 2 000 mg/kg body weight and in the vehicle controls. 2 000 polychromatic erythrocytes were evaluated per animal and investigated for micronuclei. No relevant inhibition of erythropoiesis determined from the ratio of polychromatic to normochromatic erythrocytes was detected. According to the results of the present study, the single oral administration of the test substance did not lead to any relevant increase in the number of polychromatic erythrocytes containing either small or large micronuclei.

In the course of a second study, the compound was assessed for its potential to induce DNA repair synthesis (unscheduled DNA synthesis; UDS) in hepatocytes of Wistar rats in vivo at 3-hour and 14-hour sampling time. For this purpose, the test substance, suspended in corn oil, was administered once orally to male animals at dose levels of 1 000 mg/kg and 2 000 mg/kg body weight in a volume of 10 mL/kg body weight in each case. The animals were anesthetized and the hepatocytes were harvested by in situ liver perfusion 3 and 14 hours after administration of the test substance. After an attachment period of at least 2 hours the cells were incubated for 4 hours with radiolabeled thymidine in vitro. After washing the hepatocytes were cultivated overnight until fixation. After autoradiography and hematoxylin-eosin-staining three animals per test group with at least 100 cells per animal were scored for DNA repair activity (incorporation of radiolabeled thymidine). No signs of toxicity were observed after administration of 1 000 mg/kg and 2 000 mg/kg body weight at both sacrifice intervals. No reduced viability of hepatocytes as indication for test substance induced toxicity was observed. The single oral administration of the test item did not lead to an increase in the mean net nuclear grain counts at any dose level at both sacrifice intervals.

Results and Discussion

According the Ames tests performed, the substance has a mutagenic potential at precipitating concentrations. Examination of cytotoxicity was not undertaken, thus, a false positive result due to cytotoxic effects cannot be excluded. Beside the mutagenicity in bacteria, the test material was also examined in vivo: the test material did not induce DNA-damage leading to increased unscheduled DNA synthesis and it did not induce cytogenetic damage in bone marrow cells. Thus, the substance is not considered to be genotoxic in vivo.


Short description of key information:
The test item was evaluated in several Ames tests (GLP and non-GLP) as well as in an UDS and a micronucleus assay in vivo (according GLP and concurrent OECD guideline). In three of the nine Ames tests the material was mutagenic at precipitating concentrations. The substance did not induce unscheduled DNA synthesis or micronuclei in vio.

Endpoint Conclusion: No adverse effect observed (negative)

Justification for classification or non-classification

Dangerous Substance Directive (67/548/EEC)

The available studies are considered reliable and suitable for classification purposes under 67/548/EEC. As a result the substance is not considered to be classified for genotoxicity under Directive 67/548/EEC, as amended for the 30th time in Directive 2008/58/EC.

 

 

Classification, Labeling, and Packaging Regulation (EC) No. 1272/2008

The available experimental test data are reliable and suitable for classification purposes under Regulation 1272/2008. As a result the substance is not considered to be classified for genotoxicity under Regulation (EC) No. 1272/2008, as amended for the second time in Directive (EC 286/2011).