7,7-dimethyl-3-oxa-6-azaoctan-1-ol

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:

experimental study

Adequacy of study:

key study

Reliability:

2 (reliable with restrictions)

Rationale for reliability incl. deficiencies:

other: Study conducted in accordance with generally accepted scientific principles, possibly with incomplete reporting or methodological deficiencies, which do not affect the quality of the relevant results.

Data source

Reference

Reference Type:

study report

Title:

Unnamed

Year:

1988

Report date:

1988

Materials and methods

Test guideline

Qualifier:

equivalent or similar to guideline

Guideline:

OECD Guideline 474 (Mammalian Erythrocyte Micronucleus Test)

Deviations:

not specified

GLP compliance:

not specified

Type of assay:

micronucleus assay

Test material

Test material information

Constituent 1

Reference substance name:

7,7-dimethyl-3-oxa-6-azaoctan-1-ol

EC Number:

400-390-6

EC Name:

7,7-dimethyl-3-oxa-6-azaoctan-1-ol

Cas Number:

87787-67-5

Molecular formula:

Hill formula: C8 H19 N O2 CAS formula: C8 H19 N O2

IUPAC Name:

2-[2-(tert-butylamino)ethoxy]ethan-1-ol

Details on test material:

- Name of test material (as cited in study report): MRD-88-192
- Physical state: Clear, colourless liquid
- Analytical purity: 100%
- Storage condition of test material: Room temperature

Test animals

Species:

mouse

Strain:

CD-1

Sex:

male/female

Details on test animals or test system and environmental conditions:

TEST ANIMALS
- Source: Charles River Breeding Laboratories Inc, Kingston, N.Y 12484
- Age at study initiation: Approx 9-10
- Weight at study initiation: 20 -40 grams at initiation
- Assigned to test groups randomly: yes - study animals were selected using a computer generated, body weight sorting program.
- Housing: Suspended stainless steel cage (after a week of group housing all animals were then single housed)
- Diet (e.g. ad libitum): Purina Certified Chow (pellets), ad libitum
- Water (e.g. ad libitum): Automatic watering system, ad libitum
- Acclimation period: 34 days.


ENVIRONMENTAL CONDITIONS
- Temperature (°C): Maintained between 68 and 76 degrees Fahrenheit
- Humidity (%): Maintained between 40 and 70% relative humidity
- Photoperiod (hrs dark / hrs light): Approx 12 hours light and 12 hours dark, maintained by automatic timer.

Administration / exposure

Route of administration:

oral: gavage

Vehicle:

- Vehicle(s)/solvent(s) used: Water (reagent grade water).
- Justification for choice of solvent/vehicle: The vehicle is considered, under the conditions of the assay, to be stable for the duration of the assay.

Details on exposure:

PREPARATION OF DOSING SOLUTIONS:
The test material was weighed out and on the day of dosing mixed with the vehicle to provide stock solutions such that individual animal doses (volume) did not exceed 1.0 ml / 100 grams bodyweight.


The test material and vehicle were administered by oral gavage as a single dose.

Duration of treatment / exposure:

Dosed once.

Frequency of treatment:

Dosed once.

Post exposure period:

72 hours (bone marrow samples collected 24, 48 and 72 hours after dosing).

Doses / concentrations

Doses / concentrations 1

Remarks:

Doses / Concentrations:
0.15 gram/kg
Basis:
actual ingested

Doses / concentrations 2

Remarks:

Doses / Concentrations:
0.375 gram/kg
Basis:
actual ingested

Doses / concentrations 3

Remarks:

Doses / Concentrations:
0.75 gram/kg
Basis:
actual ingested

No. of animals per sex per dose:

5 per sex per dose.

Control animals:

yes, concurrent vehicle

Positive control(s):

cyclophosphamide
- Justification for choice of positive control(s): Considered to have been stable for the duration of the assay since it produced the expected level of mutagenic activity.
- Route of administration: intraperitoneal injection.
- Doses / concentrations: cyclophosphamide was dosed at 40 mg/kg

Examinations

Tissues and cell types examined:

Erythrocytes in bone marrow.

Details of tissue and slide preparation:

CRITERIA FOR DOSE SELECTION: A rangefinding study was performed using three doses, 2.0, 1.0 and 0.5 grams test material/kg body weight. One female and one male were used for each dose group.

All animals at 0.5 g/kg survived three days after being dosed. One animal at 1.0 g/kg survived three days after being dosed. Therefore, 0.75 g/kg was used as the top dose in the assay.


TREATMENT AND SAMPLING TIMES ( in addition to information in specific fields):
Animals were euthaized by CO2 asphyxiation at approximately 24, 48 and 72 hours after dosing. Animals dosed with cyclophosphamide were sacrificed at 24 hours only.
Immediately upon euthanization of the animals, both femurs were removed. The bone marrow was then removed and suspended in fetal bovine serum. After the suspension was centrifuged, the pellet was resuspended and smears prepared (two slides per animal).


DETAILS OF SLIDE PREPARATION:
Slides were stained using acridine orange.


METHOD OF ANALYSIS:
Microscopic evaluation:
Polychromatic erythrocytes (PCE) stain flourescent red/orange, normochromatic erythrocytes (NCE) are unstained or stain a dull green, and micronuclei stain bright yellow. Additional criteria for scoring micronuclei are circular appearance and a diameter between 1/20 and 1/5 of the cells diameter.



OTHER:

Evaluation criteria:

1000 polychromatic erythrocytes (PCE) from each animal were examined for micronuclei, and the ratio of PCE's to NCE's was determined for each animal by counting 1000 erythrocytes (PCE's and NCE's).

Statistics:

Statistical analysis included calculation of means and standard deviations of the micronuclei data and a test of equality of group means by a standard one way analysis of variance at each time period. When the ANOVA was significant, comparisons of vehicle control to dosed group means were by Duncans Multiple Range Test.

Residuals from the ANOVA were analysed for normality by Wilk's Criterion. The residuals were normally distributed (at the 0.01 level of significance) in more than 25% of the analyses. Therefore nonparametric analyses were not performed.

Dose related response was evaluated by Jonkheere's Test for Ordered Response.

Sexes were analyzed separately.

Results and discussion

Test results

Sex:

male/female

Genotoxicity:

negative

Toxicity:

yes

Remarks:

Overt toxicity was observed at 48 hours in the 0.75 g/kg dose group in males only

Vehicle controls validity:

valid

Negative controls validity:

not examined

Positive controls validity:

valid

Additional information on results:

Micronucleus Assay:
Neither a statistically signficant positive response not a dose related increase in the number of micronuclei was observed at 24, 48 or 72 hours.
Overt toxicity, as measured by a statistically signficant decrease in the percentage of polychromatic erythrocytes, was observed at 48 hours in the 0.75 g/kg dose group for the males only. The percentages of polychromatic erythrocytes observed were within the range expected for healthy mice. All postive and negative (vehicle) controls responded in a manner consistent with data from previous studies.

Necropsy:
One animal died during the study (a female in the 0.375 g/kg group).
Necropsy findings: Uterus/cervix; moderately enlarged, filled with clear colourless liquid.
The exact casue of death for this animal is unknown.

Any other information on results incl. tables

Table 1 (attached background material): Data Report Summary - Contains data for the three time points by listing the means and standard deviations of the micronuclei data for each dose group and sex.

Applicant's summary and conclusion

Conclusions:

Interpretation of results (migrated information): negative
The test substance did not induce a notable (either statistically or biologically significant increase in micronucleus formation in either sex of mice.
The assay contained positive (cyclophosphamide) and negative (vehicle) controls which responded in an appropriate manner. Under the conditions of the assay, the test substance does not produce clastogenic abnormalities for CD-1 mice at doses up to and including 0.75 gram/kg at the times tested.

Executive summary:

The objective of the study was to determine whether the test substance was capable of inducing micronuclei formation in mouse bone marrow.

Test concentrations were 0.15, 0.375 and 0.75 g/kg administered by gavage in single doses. Levels exceeding 0.75 g/kg were toxic. Bone marrow samples were collected and evaluated for micronucleus formation 24, 48 and 72 hours after dosing.

The test substance did not induce a statistically significant increase in micronucleus formation at any of the collection times surveyed. Thus the test substance was not clastogenic in mouse bone marrow under the conditions of this test.