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Two studies were performed to investigate the genotoxicity of CTFEP, an in vitro chromosome aberration test and an Ames test.

The in vitro chromosome aberration with CTFEP (purity 91.4%) in Chinese Hamster V79 cells was determined in a GLP compliant test according to OECD 473, EU Method B.10 and OPPTS 870.5375. Since the study from Czich (2001) was performed under GLP and according the guideline and based on the good documentation the study was awarded with Klimisch 1. Cytotoxicity was observed after treatment with 300 µg/mL and above in the absence of S9 mix and with 600 µg/mL and above in the presence with S9 mix. In the absence of S9 mix no increased aberration frequencies s were observed. In the presence of S9 mix at interval 18 h, in experiment IA and IB, statistical significant and biological relevant increase in the cells carrying structural chromosomal aberrations were observed after treatment with the test item. In experiment IA cultures after treatment with 150, 300, 350 and 425 µg/mL revealed a dose related increase (1.0, 2.0, 3.0 and 9.0 % aberrant cells excluding gaps) whereas after treatment with 500 µg/mL the aberration frequency was at the border of the historical control data (0.0 to 4.0 % aberrant cells excluding gaps). Therefore a confirmatory experiment was performed revealing dose related increased aberration frequencies with 275, 350 and 425 µg/mL (2.5, 11.5 and 19.5 % aberrant cells excluding gaps). It has to be mentioned that increased aberration frequencies were observed only in the presence of strong test item induced toxicity at the early preparation interval (18 hrs). At the late preparation interval (28 hrs), no increased aberration frequencies were observed, indicating that the damaged cells did not survive. Therefore, it can not be excluded that indirect non-genotoxic DNA damaging mechanisms were responsible for this result.

The study from Sokolowski (2001) was performed to investigate the potential of CTFEP (purity 91.4 %) to induce gene mutations according to the plate incorporation test (experiment I) and the pre-incubation test (experiment II) using the Salmonella typhimurium strains TA 1535, TA 1537, TA 98, TA 100, and TA 102, and the Escherichia coli strain WP2 uvrA. The assay was performed under GLP following OECD 471 and EU method B.13/14 and based on the good documentation the study was awarded with Klimisch 1. The assay was performed with and without liver microsomal activation (S9 mix). Each concentration, including the controls, was tested in triplicate. The test item was tested at following concentrations: 33, 100, 333, 1000, 2500, and 5000 µg/plate. In both experiments, toxic effects, evident as the number of revertants, were observed at higher concentrations with and without metabolic activation in both independent experiments. The plates incubated with the test item showed normal background growth up to the 5000 µg/plate with and without metabolic activation in both independent experiments. No precipitation of the of the test item occurred up to the highest investigated dose. No substantial increase in revertant colony numbers of any of the six strains was observed following treatment with the test item at any dose level, neither in the presence nor absence of metabolic activation. There was no tendency of higher mutation rates with increasing concentrations in the range below the generally acknowledged border of biological relevance. Appropriate reference substances were used as positive controls and showed a distinct increase of induced revertant colonies. In conclusion, it can be stated that during the described mutagenicity test and under the experimental conditions described, the test item did not induce gene mutations by base pair changes or frameshifts in the genome of the strains used. Therefore the test item is considered to be non-mutangenic in this Salmonella typhimurium and Escherichia coli reverse mutation assay.

The obtained results of both studies are considered as relevant for the risk assessment.


Endpoint Conclusion: No adverse effect observed (negative)

Justification for classification or non-classification