2,11-Dioxa-3,10-disiladodecane, 3,3,10,10-tetramethoxy-

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:

2009-12-30 - 2010-01-19

Reliability:

1 (reliable without restriction)

Rationale for reliability incl. deficiencies:

other: The study was conducted according to an appropriate EU test method, and in compliance with GLP.

Data source

Reference

Reference Type:

study report

Title:

Unnamed

Year:

2010

Report date:

2010

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:

Reference substance 001

Cas Number:

87135-01-1

Molecular formula:

C12H30O6Si2

Constituent 2

Reference substance name:

3,3,10,10-tetramethoxy-2,11-dioxa-3,10-disiladodecane

EC Number:

617-969-6

Cas Number:

87135-01-1

Molecular formula:

(CH3O)3Si(CH2)6Si(OCH3)3 C12 H30 O6 Si2

IUPAC Name:

3,3,10,10-tetramethoxy-2,11-dioxa-3,10-disiladodecane

Test material form:

other: liquid

Test animals

Species:

rat

Strain:

Sprague-Dawley

Sex:

male

Details on test animals or test system and environmental conditions:

TEST ANIMALS
- Age at study initiation: 6 - 8 weeks old
- Weight at study initiation: 195.0 - 212.1 g
- Assigned to test groups randomly: [no/yes, under following basis: ] yes
- Fasting period before study: no
- Housing: five per Micro-Barrier cage
- Diet (e.g. ad libitum): ad libitum
- Water (e.g. ad libitum): ad libitum
- Acclimation period: 5 days

ENVIRONMENTAL CONDITIONS
- Temperature (°C): 72 ± 3ºF
- Humidity (%): 50 ± 20%
- Air changes (per hr): 10 changes of fresh HEPA-filtered air every hour
- Photoperiod (hrs dark / hrs light): 12 hour light/dark cycle

Administration / exposure

Route of administration:

oral: gavage

Vehicle:

- Vehicle(s)/solvent(s) used: corn oil
- Justification for choice of solvent/vehicle: none given
- Concentration of test material in vehicle: 215, 250 and 500 mg/ml
- Amount of vehicle (if gavage or dermal): 4 ml/kg
- Purity: no information

Details on exposure:

PREPARATION OF DOSING SOLUTIONS:
Appropriate amount of test substance was weighed into separate containers for each concentration. Vehicle (approximately 80% of final volume) was added, and the formulation vortexed briefly and stirred (magnetic stirrer) for approximately 10 minutes. Remaining volume of vehicle added and stirred for a further 10 minutes. Formulations appeared as yellow solutions.

The route of administration was chosen based on bioavailability data indicating that the substance is well absorbed on oral administration.

Duration of treatment / exposure:

24 and 48 hours

Frequency of treatment:

Test compound and vehicle control were administered once by oral gavage, positive control was administered by intraperitoneal injection.

Post exposure period:

The positive control group was sacrificed 24 hours after administration of the test substance. The vehicle control and test substance groups, except the low and mid dose group which were sacrificed at 24 hours only, were sacrificed 24 and 48 hours after administration of the test substance.

Doses / concentrations

Remarks:

Doses / Concentrations:
500, 1000 and 2000 mg/kg bw
Basis:
nominal conc.

No. of animals per sex per dose:

Five

Control animals:

yes, concurrent vehicle

Positive control(s):

- cyclophosphamide (CP)
- Justification for choice of positive control(s): Accuracy of preparation and stability of the CP formulation was demonstrated by the acceptable results that met the criteria for a valid test.
- Route of administration: intraperitoneal injection
- Doses / concentrations: 40 mg/kg

Examinations

Tissues and cell types examined:

2000 Polychromatic erythrocytes (PCEs) per each animal were scored for the presence of micronuclei. The number of normochromatic erythrocytes (NCE's) and micronucleated NCE'S (MNCEs) in the field of 1000 total erythrocytes (ECs) is determined for each animal in order to determine the proportion of polychromatic erythrocytes to total erythrocytes (PCE/EC ratio).

Details of tissue and slide preparation:

CRITERIA FOR DOSE SELECTION: limit dose based on toxicity data generated by study Sponsor.

TREATMENT AND SAMPLING TIMES ( in addition to information in specific fields):

DETAILS OF SLIDE PREPARATION: Following centrifugation of bone marrow cells and having drawn off the supernatant, the cells were re-suspended in a small amount of serum and spread onto a clean glass slide. Two slides per animal were air dried and fixed with methanol. Slides were stained with a nucleic acid-specific stain, acridine orange.

METHOD OF ANALYSIS: Following randomised coding, a fluorescent microscope and medium magnification (400X; blue excitation filter in the range of 440-490 nm and barrier filter combination at 520 nm) was used to score cells that were well spread and stained.

OTHER:

Evaluation criteria:

The test substance would have been considered to induce a positive response if a dose-responsive increase in the incidence of micronucleated polychromatic erythrocytes was observed and one or more doses were statistically elevated relative to the vehicle control at any sampling times.

Statistics:

Kastenbaum-Bowman Tables

Results and discussion

Test results

Sex:

male

Genotoxicity:

negative

Toxicity:

no effects

Vehicle controls validity:

valid

Negative controls validity:

not applicable

Positive controls validity:

valid

Any other information on results incl. tables

Summary of bone marrow micronucleus assay

Treatment (4 ml/kg)	Time (hr)	Number of animals	Mean PCE/total erythrocytes	Change from control (%)	% mean MPCE	Number of MPCE/PCE scored
Solvent control	24	5	0.530	-	0.03	3
500	24	5	0.562	6	0.04	4
1000	24	5	0.539	2	0.02	2
2000	24	5	0.570	8	0.05	5
Positive control	24	5	0.435	-18	1.49	149
Solvent control	48	5	0.499	-	0.05	5
2000	48	5	0.503	1	0.06	6

Applicant's summary and conclusion

Conclusions:

Interpretation of results (migrated information): negative
1,6-Bis(trimethoxysilyl)hexane has been tested in an in vivo rat micronucleus assay which was conducted according to OECD 474 and in compliance with GLP. No evidence of test substance related induction of micronuclei was observed following administration of the test substance by oral gavage at doses of 500, 1000 and 2000 mg/kg bw. No reduction in the ratio of PCEs to total erythrocytes was observed. Appropriate vehicle and positive controls were included and gave expected results. It is concluded that the test substance is not clastogenic under the conditions of the test.