Registration Dossier

Administrative data

Endpoint:
in vivo mammalian somatic cell study: cytogenicity / erythrocyte micronucleus
Type of information:
experimental study
Adequacy of study:
key study
Study period:
1 September 1998 - 3 October 1998
Reliability:
1 (reliable without restriction)
Rationale for reliability incl. deficiencies:
guideline study

Data source

Reference
Reference Type:
study report
Title:
Unnamed
Year:
1998
Report Date:
1998

Materials and methods

Test guideline
Qualifier:
according to
Guideline:
OECD Guideline 474 (Mammalian Erythrocyte Micronucleus Test)
Deviations:
no
GLP compliance:
yes
Type of assay:
micronucleus assay

Test material

Reference
Name:
Unnamed
Type:
Constituent

Test animals

Species:
mouse
Strain:
NMRI
Sex:
male/female
Details on test animals and environmental conditions:
TEST ANIMALS

- Source: Harlan-Winkelmann GmbH, D-33176 Borchen

- Age at study initiation: approximately 7 weeks

- Weight at study initiation: males: 27.4-33.8 g; female: 22.0-26.1g

- Assigned to test groups randomly: yes, under following basis: computerised random number generator.

- Fasting period before study:

- Housing: Macrolon cages type II, 1 animal per cage

- Diet (e.g. ad libitum): ad libitum

- Water (e.g. ad libitum): ad libitum

- Acclimation period: at least 6 days


ENVIRONMENTAL CONDITIONS

- Temperature (°C): 21.0-21.5°C

- Humidity (%): 50-57%

- Air changes (per hr):

- Photoperiod (hrs dark / hrs light): 12 hrs dark/12 hrs light


IN-LIFE DATES: From: To: 3 Sept 1998

Administration / exposure

Route of administration:
intraperitoneal
Vehicle:
- Vehicle(s)/solvent(s) used: peanut oil
- Lot/batch no. (if required): 1936301
Details on exposure:
Route of exposure: intraperitoneal
Duration of treatment / exposure:
46-48 hours
Frequency of treatment:
2 intraperitoneal administrations of 10 ml/kg bw with an interval of approximately 24 hours (test material and negative control group). Positive control group received a single injection of 10 ml/kg bw
Post exposure period:
Animals were sacrificed 22-24h after second (test and negative control) or single (positive control) administration.
Doses / concentrations
Dose / conc.:
2 000 mg/kg bw/day (nominal)
No. of animals per sex per dose:
7
Control animals:
yes, concurrent vehicle
Positive control(s):
- cyclophosphamide
- Justification for choice of positive control(s): standard guideline positive control
- Route of administration: intraperitoneal
- Doses / concentrations: 10 ml/kg bw of 0.9% solution in physiological saline

Examinations

Tissues and cell types examined:
See table 2
Details of tissue and slide preparation:
CRITERIA FOR DOSE SELECTION: limit dose
TREATMENT AND SAMPLING TIMES (in addition to information in specific fields): no further information


DETAILS OF SLIDE PREPARATION: centrifuged cells were suspended in a thin layer of serum, and a small drop was smeared on a slide and air-dried overnight. The dried slides were stained using the panoptic stain method of Pappenheim (Queisser W (1978) Das Knochenmark, Georg Thieme Verlag, Stuttgart)


METHOD OF ANALYSIS: microscopic examination. 2000 PCE scored for incidence of polychromatic erythrocytes with micronuclei. Ratio of PCE/NCE was scored based on 1000 erythrocytes (PCE+NCE)

Statistics:
Frequencies of PCE with micronuclei of test material and of positive control group were compared with those of the negative control group. A Poisson test was applied. Data from each treatment group for each sex and for the sexes combined were compared with appropriate negative control using software from ASTA medica AG and an Alpha computer (Digital Equipment Corp)

Results and discussion

Test results
Key result
Sex:
male/female
Genotoxicity:
negative
Toxicity:
no effects
Vehicle controls validity:
valid
Negative controls validity:
not applicable
Positive controls validity:
valid
Additional information on results:
See table 3
RESULTS OF DEFINITIVE STUDY

- Induction of micronuclei (for Micronucleus assay): negative

- Ratio of PCE/NCE (for Micronucleus assay): see table 3. The PCE/NCE ratio was unchanged in treated animals, so there is no evidence that the test substance reached the target tissue.

- Appropriateness of dose levels and route: appropriate dose and route

- Statistical evaluation: no statistically significant induction of micronuclei occurred

Any other information on results incl. tables

Table 3: Results of in vivo micronucleus test with Silane Si 266

 

 

Vehicle Control

Positive control

2000 mg/kg bw

Number of cells evaluated

 2000

2000

2000 

Sampling time (h)

24 

 24

 24 

Number of erythrocytes per animal

normo­chromatic

NR

NR

NR

poly­chromatic

2000

2000

2000

polychromatic with micronuclei

3.4

38.1

3.4

Ratio of erythro­cytes

polychromatic / normochromatic

1.9*

1.5*

1.8*

polychromatic with micro­nuclei / normochromatic

NR

NR

NR

 * Mean calculated from data for individual animals

PCE polychromatic erythrocyte

NR not recorded

Applicant's summary and conclusion

Conclusions:
S2 was tested in an in vivo mouse micronucleus assay conducted to OECD 474 and in compliance with GLP. No evidence of genotoxicity was observed under the conditions of the test. It should be noted that the PCE/NCE ratio was unchanged in treated animals, so there is no evidence that the test substance reached the target tissue. It is concluded that the test substance is negative for the induction of micronuclei in vivo.