2,2,6,6-tetramethylpiperidin-4-ol

Endpoint summary

Additional information

2,2,6,6 -tetramethylpiperidin-4 -ol has been investigated in in vitro tests, gene mutation in bacterial systems with and without an exogenous metabolic activation systems. Also a micronucleus assay using rats was performed.

In vitro: Two reverse gene mutation assay were reviewed (MHW, Japan, 1998 and Ciba GmbH Lampertheim, 1984), and the MHW study was identified to be a key study because it was conducted according to OECD TG 471 and well reported. 2,2,6,6 -tetramethylpiperidin-4 -ol was tested for mutagenic activity in Salmonella typhimurium strains TA 1535, TA 1537, TA 98, TA 100 and Escherichia coli WP2uvrA at concentrations ranging from 156 to 5000 µg per plate (MHW, 1998). The tests were conducted, using the pre-incubation method, on agar plates in the presence and absence of an induced rat liver preparation and co-factors (S9 mix) required for mixed-function oxidase activity. Positive control compounds demonstrated the sensitivity of the assay and the metabolising, potential of the S9 mix. The substance was not mutagenic in Salmonella typhimurium TA100, TA1535, TA98, TA 1537 and Escherichia coli WP2 uvrA at concentrations of up to 5000 µg/plate, with and without an exogenous metabolic activation system (MHW, Japan, 1998). The other study showed negative results as well (Ciba, 1984).

Further a chromosome aberration assay was performed (Mitsui Chemical Inc., 1998) using CHL/IU cells derived from lungs of female Chinese hamster. The concentrations in the chromosomal aberration test were set at 4 concentrations including 1/2, 1/4, and 1/8 of the highest concentration. As a result, cells with structural or numerical chromosome aberration were not induced at any treatment conditions. However, in the short-term treatment assay without S9 mix, mitotic index at the highest concentration was 6.6 and it was considered that chromosome analysis at higher concentration should be possible. Therefore, the additional test was conducted at up to 2000µg/ml. As a result, structural chromosome aberration was induced at 2000 µg/ml in the short-term

treatment assay without S9 mix. The reproducibility was not recognized in the induction of cells with numerical chromosome aberration. In conclusion, as 2,2,6,6 -tetramethylpiperidin-4 -ol induced structural chromosomal aberration without S9 mix only at concentrations higher than the 50% cell growth inhibitory concentration, which was considered to be equivocal.

In vivo: A micronucleus assay was performed (MHLW 2002). This assay with bone marrow cells of rats was performed in accordance with the OECD TG 474. This substance was administered twice orally (during a 24 hour interval) to male Crj:CD ( SD) IGS rats at 250, 500, 1000 and 1500 mg/kg bw. The incidence of micronucleated immature erythrocytes was evaluated in rat bone marrow 22 to 24 hours after the final administration. Distilled water was used as a negative control, and cyclophosphamide monohydrate (CP) 20 mg/kg as a positive control. The result of this assay was as follows.

1) No significant increase was noted in the frequency of micronucleated immature erythrocytes in any test article group, in comparison with the negative control group. A significant low value was noted in the immature erythrocyte ratio of all doses compared to the negative control group. 1 of 6 animal died at 1500 mg/kg bw.

2) A significant difference was noted in the frequency of micronucleated immature erythrocytes and in the ratio of immature erythrocytes in the positive control group compared to the negative control group.

3) Alter exposure of the test article to bone marrow erythrocytes in rats, it was confirmed that a significant decrease in the immature erythrocyte ratio occurred at all doses compared to the negative control group. Therefore, it was concluded from the results described above, that under the conditions of this study, this substance did not induce clastogenic activity in the bone marrow erythrocytes of rats.

Conclusions: This substance was not mutagenic with or without an exogenous metabolic activation in bacteria [OECD TG 471 & 472]. A negative result was obtained in a rat bone marrow micronucleus assay [OECD TG 474]. Thus, on the basis of the available

data, this substance is not considered to be an in vivo genotoxicant.

Short description of key information:
in vitro: Ames: negative, GLP-OECD Guideline, MHW, 1998
Ames: negative, Ciba, 1984
chromosome aberration: equivocal, MHLW, 1998
in vivo: Micronucleus test: negativ, GLP-OECD Guideline, Mitsui, 2002

Endpoint Conclusion: No adverse effect observed (negative)

Justification for classification or non-classification

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

The available experimental test data are reliable and suitable for the purpose of classification under Regulation (EC) No.1272/2008. Based on the present data (not genotoxic in in vitro experiments using bacterial cells and in an in-vivo rat micronucleus assay using bone marrow cells), classification for genotoxicity is not warranted under Regulation (EC) No.1272/2008.