Sodium 2-methylpropan-2-olate

Genetic toxicity: in vivo

Administrative data

Endpoint:

in vivo mammalian somatic cell study: cytogenicity / erythrocyte micronucleus

Remarks:

Type of genotoxicity: chromosome aberration

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: Well described study and suitable for assessment.

Data source

Reference

Reference 1

Reference Type:

secondary source

Title:

Unnamed

Year:

1995

Reference 2

Reference Type:

other: Publication; reference for detailed protocol

Title:

The in Vivo Erythrocyte Micronucleus Test: Measurement at Steady State Increases Assay Efficency and Permits Integration with Toxicity Studies

Author:

MacGregor JT, Wehr CM, Henika PR, Shelby MD

Year:

1990

Bibliographic source:

Fundamental and Applied Toxicology, volume 14, pages 513 - 522

Materials and methods

Principles of method if other than guideline:

Peripheral blood samples were obtained from male and female B6C3Fl mice at the end of the 13-week drinking-water toxicity study. Smears were prepared, fixed, and stained. The frequency of micronuclei in 10,000 normochromatic erythrocytes (NCB) in up to 10 animals per dose group was determined.

GLP compliance:

yes

Type of assay:

micronucleus assay

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

Test material form:

other: colorless liquid

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

Test animals

Species:

mouse

Strain:

B6C3F1

Sex:

male/female

Details on test animals or test system and environmental conditions:

TEST ANIMALS
- Source: Frederick Cancer Research Facility
- Age at study initiation: approximately 6 weeks old
- Housing: single housing
- Diet (e.g. ad libitum): NIH-07 open formula rodent feed; ad libitum
- Water (e.g. ad libitum): deionized water; ad libitum
- Acclimation period/quarantine: 13 days

ENVIRONMENTAL CONDITIONS
- Temperature (°C): 12-30 °C
- Humidity (%): 31-56 %
- Air changes (per hr): 10/hour
- Photoperiod (hrs dark / hrs light): 12/12

Administration / exposure

Route of administration:

oral: drinking water

Vehicle:

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

Details on exposure:

REPARATION OF DOSING SOLUTIONS: T-butyl alcohol was mixed with deionized water

Duration of treatment / exposure:

13 weeks

Frequency of treatment:

94-95 consecutive days in the drinking water

Doses / concentrations

Remarks:

Doses / Concentrations:
0, 2.5, 5, 10, 20 or 40 mg/mL in deionized
Basis:
nominal in water

No. of animals per sex per dose:

Male:
0: 8
2.5 mg/mL: 10
5 mg/mL: 10
10 mg/mL: 9
20 mg/mL: 9
40 mg/mL: 3

Female:
0: 9
2.5 mg/mL: 8
5 mg/mL: 10
10 mg/mL: 10
20 mg/mL: 9
40 mg/mL: 5

Control animals:

yes, concurrent vehicle

Positive control(s):

- used positive control: Urethane
- Doses / concentrations: 2,000 ppm

Examinations

Tissues and cell types examined:

Normochromatic erythrocytes

Details of tissue and slide preparation:

DETAILS OF SLIDE PREPARATION: Smears were prepared and fixed in absolute methanol, stained with a chromatin-specific fluorescent dye mixture of Hoechst 33258/pyronin Y, and coded.

METHOD OF ANALYSIS: Slides were scanned at 630x or 1,000x magnification using a semi-automated image analysis system to determine the micronuclei in 10,000 normochromatic erythrocytes (NCB).
A detailled discussion of this assay can be found in MacGregor et al., 1990.

Results and discussion

Test results

Sex:

male/female

Genotoxicity:

negative

Toxicity:

not specified

Vehicle controls validity:

valid

Negative controls validity:

not specified

Positive controls validity:

valid

Additional information on results:

RESULTS OF DEFINITIVE STUDY
- Induction of micronuclei (for Micronucleus assay): No increase in the frequency of micronucleated NCEs was observed. No effect on the percentage of PCEs was noted.

Any other information on results incl. tables

Males	Dose (mg/mL)	Micronucleated NCE cells (%)	PCE (%)	Number of Mice
	0	0.09 +/- 0.01	0.86 +/- 0.14	8
	2.5	0.10 +/- 0.01	1.03 +/- 0.07	10
	5	0.07 +/- 0.01	0.92 +/- 0.16	10
	10	0.09 +/- 0.02	0.68 +/- 0.08	9
	20	0.08 +/- 0.01	0.87 +/- 0.10	9
	40	0.06 +/- 0.03	0.52 +/- 0.25	3
Urethane	2	1.95 +/- 0.07	1.79 +/- 0.07	3
Females	Dose (mg/mL)	Micronucleated NCE cells (%)	PCE (%)	Number of Mice
	0	0.06 +/- 0.01	0.88 +/- 0.13	9
	2.5	0.04 +/- 0.01	0.68 +/- 0.10	8
	5	0.05 +/- 0.01	0.77 +/- 0.16	10
	10	0.05 +/- 0.01	0.88 +/- 0.09	10
	20	0.07 +/- 0.01	0.94 +/- 0.08	9
	40	0.07 +/- 0.01	0.81 +/- 0.18	5

Table 3: Frequency of Micronuclei in Mouse Peripheral Blood Erythrocytes Following Treatment with t-Butyl Alcohol in Drinking Water for 13 Weeks.