Registration Dossier

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: well performed GLP and OECD guideline study following a previous guideline version

Data source

Reference
Reference Type:
study report
Title:
Unnamed
Year:
1992
Report Date:
1992

Materials and methods

Test guideline
Qualifier:
according to
Guideline:
OECD Guideline 474 (Mammalian Erythrocyte Micronucleus Test)
Deviations:
yes
Principles of method if other than guideline:
Study was performed according to a previous guidline version. Following this protocol only a single dose was tested in the main study. This test dose was accurately determined in a dose range finding study in order to find the maximum dose producing dsitinct toxicity but no lethality.
GLP compliance:
yes
Type of assay:
micronucleus assay

Test material

Reference
Name:
Unnamed
Type:
Constituent
Details on test material:
- Name of test material (as cited in study report): Nitrohydrochinondimehylether

Test animals

Species:
mouse
Strain:
NMRI
Sex:
male/female
Details on test animals and environmental conditions:
TEST ANIMALS
- Source: HOECHST AG breeding colony
- Age at study initiation: 7 weeks
- Weight at study initiation: males: 25-33 g, females: 20-29 g
- Housing: ln fully air-conditioned rooms, in Macrolon cages, on softwood granulate, in groups of 5 animals
- Diet (e.g. ad libitum): rat/mice standard diet Altromin 1324, ad libitum
- Water (e.g. ad libitum): tap water, ad libitum
- Acclimation period: at least 5 days

ENVIRONMENTAL CONDITIONS
- Temperature (°C): 20±3
- Humidity (%): 50±20
- Photoperiod (hrs dark / hrs light): 12/12

Administration / exposure

Route of administration:
oral: gavage
Vehicle:
sesame oil
Details on exposure:
The test compound was suspended in sesame oil and dosed once oral at 1200 mg per kg bw to male and female mice, upon the results of the previously conducted dose range finding assay
Duration of treatment / exposure:
treatment: once oral at 1200 mg per kg bw
exposure: animals were killed 24, 48 or 72 hours after administration
Frequency of treatment:
once
Doses / concentrations
Remarks:
Doses / Concentrations:
1200 mg per kg bw, 12.0 % (w/v)
Basis:
actual ingested
No. of animals per sex per dose:
5 male and 5 female per dose group
Control animals:
yes, concurrent vehicle
Positive control(s):
Endoxan®: 50 mg/kg bw , orally

Examinations

Tissues and cell types examined:
polychromatic and normochromatic bone marrow erythrocytes
Evaluation criteria:
1000 polychromatic erythrocytes were counted for each animal. The number of cells with micronuclei was recorded. As a control measure 1000 mature erythrocytes were also counted and examined for micronuelei. In addition, the ratio of polychromatic to normochromatic erythrocytes was determined. The number of polychromatic erythrocytes with micronucIei occurring in the 1000 polychromatic erythrocytes counted, and the number of normocytes with micronuclei occurring in the 1000 normocytes counted, were evaluated statistically; comparison of dose groups with the simultaneous control group was performed according to Wilcoxon (paired, one-sided, increase) .
The results of the treatment groups (test substance) in the micronucleus test at each dose and killing time were compared with corresponding control values.The ratio of polychromatic to normochromatic erythrocytes was also evaluated statistically by the method of Wilcoxon (paired, two sided). All statistical results are based on a 95% level of significance. Actual data were also compared with historical controls.
Statistics:
Wilcoxon (paired, one-sided, increase) and Wilcoxon (paired, two sided).
All statistical results are based on a 95% level of significance.

Results and discussion

Test results
Sex:
male/female
Genotoxicity:
negative
Toxicity:
yes
Vehicle controls validity:
valid
Negative controls validity:
not examined
Positive controls validity:
valid
Additional information on results:
All animals survived after application of 1200 mg per kg bw. The following signs of toxicity were observed: reduced spontaneous activity,
narrowed palpebral fissures, ataxic gait, uncoordinated gait, stilted gait, increased tonus of the abdominanal position, piloerection, abnormal respiratory sounds and urine orange coloured.

48 hours after application all animals were free of clinical signs of toxicity.

The dissection of the animals revealed no test substance related macroscopic findings.

Applicant's summary and conclusion

Conclusions:
Interpretation of results (migrated information): negative
The results indicate that, under the conditions of the present study, Nitrohydrochinondimethylether is not mutagenic in the micronucleus test.
Executive summary:

Nitrohydrochinondimethylether was tested in the in vivo micronucleus test according to OECD 474. The test compound was suspended in sesame oil and dosed once orally at 1200 mg per kg bw to male and female mice, upon the results of the previously conducted dose range finding assay. The animals were killed 24, 48 or 72 hours after administration. Endoxan® was used as positive control substance and was administered orally at a dose of 50 mg per kg bw.

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 Nitrohydrochinondimethylether and was statistically not different from the control values. Endoxan® 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, Nitrohydrochinondimethylether is not mutagenic in the micronucleus test.