Sodium 2-methylpropan-2-olate

Genetic toxicity: in vitro

Administrative data

Endpoint:

in vitro DNA damage and/or repair study

Remarks:

Type of genotoxicity: DNA damage and/or repair

Type of information:

migrated information: read-across from supporting substance (structural analogue or surrogate)

Adequacy of study:

weight of evidence

Reliability:

2 (reliable with restrictions)

Rationale for reliability incl. deficiencies:

other: Comparable with guideline study (OECD 479) with acceptable restrictions.

Data source

Reference

Reference 1

Reference Type:

secondary source

Title:

Unnamed

Year:

1995

Reference 2

Reference Type:

publication

Title:

Chromosome Aberrations and Sister Chromatid Exchanges in Chinese Hamster Ovary Cells: Evaluation of 108 Chemicals

Author:

Galloway SM, Armstrong MJ, Reuben C, Colman C, Brown B, Cannon CJ, Bloom AD, Nakamura F, Ahmed M, Duk S, Rimpo J, Margolin BH, Resnick MA, Anderson B and Zeiger E

Year:

1987

Bibliographic source:

Environmental and Molecular Mutagenesis, volume 10, supplement 10, pages 1 - 175

Materials and methods

Test guideline

Qualifier:

equivalent or similar to guideline

Guideline:

OECD Guideline 479 (Genetic Toxicology: In Vitro Sister Chromatid Exchange Assay in Mammalian Cells)

Principles of method if other than guideline:

The teste was performed as previously reported by Galloway et al. (1987). Tert butyl alcohol was tested in cultured Chinese hamster ovary (CHO) cells for induction of sister chromatid exchanges (SCEs) in the presence and absence of Aroclor 1254-induced male Sprague-Dawley rat liver S9-mix.

GLP compliance:

not specified

Type of assay:

sister chromatid exchange assay in mammalian cells

Test material

Test material information

Constituent 1

Reference substance name:

2-methylpropan-2-ol

EC Number:

200-889-7

EC Name:

2-methylpropan-2-ol

Cas Number:

75-65-0

Molecular formula:

C4H10O

IUPAC Name:

2-methylpropan-2-ol

Details on test material:

- Name of test material (as cited in study report): t-butyl alcohol
- Physical state: clear colorless liquid
- Analytical purity: > 99 %
- Lot/batch No.: F112784
- Stability: bulk chemical is stable for 2 weeks
- Stability under test conditions: The stability of the dose formulations was at least 3 weeks at room temperature when stored in the dark and at least 3 days at room temperature under normal room light.
- Storage condition of test material: it should be protected from light at temperatures up to 60 °C

Method

Target gene:

not applicable

Species / strain

Species / strain / cell type:

Chinese hamster Ovary (CHO)

Metabolic activation:

with and without

Metabolic activation system:

S9-mix

Test concentrations with justification for top dose:

with/without S9 mix, trial 1: 160, 500, 1600, 5000 ug/mL
with/without S9 mix, trial 2: 2000, 3000, 4000, 5000 ug/mL

Vehicle / solvent:

- Vehicle(s)/solvent(s) used: medium

Controls

Untreated negative controls:

not specified

Negative solvent / vehicle controls:

yes

True negative controls:

no

Positive controls:

yes

Positive control substance:

other: without S9-mix: Mitomycin-C; with S9-mix: Cyclophosphamide

Details on test system and experimental conditions:

METHOD OF APPLICATION: in medium

CHO cells were incubated for 26 hours with t-butyl alcohol in medium. 2 hours after culture initiation bromodeoxyuridine (BrdU) was added. After 26 hours, the medium (incl. t-butyl alcohol) was removed and replaced by fresh medium plus BrdU and Colcemid, and incubation was continued for 2 hours. Cells were then harvested, fixed, and stained with Hoechst 33258 and Giemsa.
In the SCE test with S9, cells were incubated with t-butyl alcohol in medium and S9-mix for 2 hours. Afterwards, the medium was removed and replaced with medium containing serum and BrdU and no t-butyl alcohol. Cells were incubated for an additional 26 hours, with Colcemid present for the final 2 hours. Harvesting and staining were the same as for cells treated without S9-mix.

SPINDLE INHIBITOR (cytogenetic assays): Colcemid
STAIN (for cytogenetic assays): Hoechst 33258 and Giemsa

NUMBER OF CELLS EVALUATED: 50 second division metaphase cells were scored

Statistics:

Statistical analyses were conducted on the slopes of the dose-response curves and the individual dose points. An SCE frequency of 20% above the concurrent solvent control value was chosen as a statistically conservative positive response. An increase of 20% or greater at any single dose was considered weak evidence of genotoxicity; increases at two or more doses resulted in a trial that was positive. A statistically significance (P

Results and discussion

Test results

Species / strain:

Chinese hamster Ovary (CHO)

Metabolic activation:

with and without

Genotoxicity:

negative

Cytotoxicity / choice of top concentrations:

no cytotoxicity

Vehicle controls validity:

valid

Untreated negative controls validity:

not specified

Positive controls validity:

valid

Remarks on result:

other: all strains/cell types tested

Remarks:

Migrated from field 'Test system'.

Any other information on results incl. tables

4 experiments have been performed: two with S9 mix, two without S9 mix. The first experiment without S9 mix was "weakly positive". The number of SCEs / chromosome was significantly increased in the 5000 µg/mL dose group without presence of cytotoxicity. Experiment with S9 -mix was negative. For that reason, a second experiment was done. The positive result from test 1 was not reproducible in the second experiment (with and without S9 mix). For that reason, the test substance was considered to be negative in this SCE test.