Exo-1,7,7-trimethylbicyclo[2.2.1]hept-2-yl acetate

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

Study period:

January 14th to 17th, 1991

Reliability:

1 (reliable without restriction)

Rationale for reliability incl. deficiencies:

other: Meets GLP and guideline requirements.

Data source

Reference

Reference Type:

study report

Title:

Unnamed

Year:

1991

Report date:

1991

Materials and methods

Test guideline

Qualifier:

according to guideline

Guideline:

OECD Guideline 474 (Mammalian Erythrocyte Micronucleus Test)

GLP compliance:

yes

Type of assay:

micronucleus assay

Test material

Test material information

Constituent 1

Reference substance name:

Exo-1,7,7-trimethylbicyclo[2.2.1]hept-2-yl acetate

EC Number:

204-727-6

EC Name:

Exo-1,7,7-trimethylbicyclo[2.2.1]hept-2-yl acetate

Cas Number:

125-12-2

Molecular formula:

C12H20O2

IUPAC Name:

1,7,7-trimethylbicyclo[2.2.1]hept-2-yl acetate

Details on test material:

- Name of test material (as cited in study report): Isobornylacetat-Extra
- Physical state: liquid
- Analytical purity: 93.5 – 95.0 % Isobornylacetat
- Impurities (identity and concentrations): other terpene esters and camphene
- Composition of test material, percentage of components:
94.6 % Isobornylacetat
2.8 % Isofenchylacetat
0.8 % Pseudobornylacetat
0.5 % Fenchylacetat
0.4 % Isoborneol
0.1 % Camphen
- Lot/batch No.: 249/90
- Storage condition of test material: dark, at room temperature

Test animals

Species:

mouse

Strain:

NMRI

Sex:

male/female

Details on test animals or test system and environmental conditions:

TEST ANIMALS
- Source: HOECHST AG, Kastengrund, SPF breeding colony
- Age at study initiation: 7 weeks
- Weight at study initiation: 28.7 g (males) and 22.8 g (females)
- Housing: in fully air-conditioned rooms in Macrolon cages (Type 3), on softwood granulate in groups of 5 animals
- Diet (e.g. ad libitum): ad libitum
- Water (e.g. ad libitum): ad libitum
- Acclimation period: at least 5 days

ENVIRONMENTAL CONDITIONS
- Temperature (°C): 22 ± 2 °C
- Humidity (%): 55 ± 10 %
- Photoperiod (hrs dark / hrs light): 12 hours daily

Administration / exposure

Route of administration:

oral: gavage

Vehicle:

- Vehicle(s)/solvent(s) used: sesame oil

Duration of treatment / exposure:

only one administration

Frequency of treatment:

once

Post exposure period:

24, 48 and 72 hours

Doses / concentrations

Dose / conc.:

2 000 mg/kg bw/day (actual dose received)

No. of animals per sex per dose:

70 animals (35 male and 35 female):
Group 1: 0 mg/kg bw (5 males and 5 females) killing time: 24 h post administration
Group 2: 2000 mg/kg bw (5 males and 5 females) killing time: 24 h post administration

Group 4: 0 mg/kg bw (5 males and 5 females) killing time: 48 h post administration
Group 5: 2000 mg/kg bw (5 males and 5 females) killing time: 48 h post administration
Group 6: 0 mg/kg bw (5 males and 5 females) killing time: 72 h post administration
Group 7: 2000 mg/kg bw (5 males and 5 females) killing time: 72 h post administration

Control animals:

yes

Positive control(s):

Endoxan(R):
Group 3: Cyclophosphamide 50 mg/kg bw (5 males and 5 females) killing time: 24 h post administration (positive control)
- Route of administration: oral, by gavage
- Doses / concentrations: 50 mg/kg bw

Examinations

Tissues and cell types examined:

Polychromatic and normochromatic erytrocytes

Details of tissue and slide preparation:

DETAILS OF SLIDE PREPARATION: staining with Giemsa

Statistics:

Comparison of dose groups with the simultaneous control group was performed according to Wilcoxon (paired, one-sided, increase).
The ratio of polychromatic to normochromatic erythrocytes was also evaluated statistically by the method of Wilcoxon (paired, two sided).

Results and discussion

Test results

Sex:

male/female

Genotoxicity:

negative

Toxicity:

yes

Remarks:

Uncoordinated gait, increased spontaneous activity. 5-6 hours after application all animals were free of clinical signs of toxicity.

Vehicle controls validity:

valid

Positive controls validity:

valid

Additional information on results:

RESULTS OF RANGE-FINDING STUDY: Preliminary studies were conducted to determine the highest administrable non lethal dose level.
- Doses: 5000, 4000, 3000 and 2000 mg/kg
- Clinical signs of toxicity in test animals: increased spontaneous activity, impaired gait, impaired general condition, reduced spontaneous activity, etc.
The 2000 mg per kg bodyweight dose level was chosen since it had shown to be the maximum non lethal dose.

Applicant's summary and conclusion

Conclusions:

Interpretation of results: negative
Isobornyl acetate was non mutagenic.

Executive summary:

Isobornylacetat - Extra was tested in the micronucleus test, according to OECD guideline 474. The test compound was administered orally by gavage to male and female mice. The following doses were tested: 0 and 2000 mg Isobornylacetat - Extra per kg bodyweight.

The 2000 mg per kg bodyweight dose level was chosen since a preliminary study had shown it to be the maximum non lethal dose.

The animals were treated once with the test compound and according to the test procedure the animals were killed 24, 48 or 72 hours after administration of the test compound.

Cyclophosphamide was used as positive control substance and was administered orally at a dose of 50 mg per kg bodyweight.

The number of polychromatic and normochromatic erythrocytes containing micronuclei was not increased. The ratio of polychromatic/normochromatic erythrocytes in both male and female animals remained unaffected by the treatment with Isobornylacetat - Extra and was statistically not different from the control values.

Cyclophosphamide induced in both males and females a marked statistically significant increase in the number of polychromatic cells with micronuclei, indicating the sensitivity of the system. The ratio of polychromatic erythrocytes to normocytes was not changed to a significant extent.

The results indicate that, under the conditions of the present study, Isobornylacetat - Extra is not mutagenic in the micronucleus test.