Dichloro(methyl)(phenyl)silane

Genetic toxicity: in vivo

Administrative data

Endpoint:

in vivo mammalian somatic cell study: cytogenicity / erythrocyte micronucleus

Type of information:

experimental study

Adequacy of study:

key study

Study period:

1991-05-07 to 1991-05-27

Reliability:

2 (reliable with restrictions)

Rationale for reliability incl. deficiencies:

guideline study with acceptable restrictions

Remarks:

The restrictions were that less detail was given than is usual in a standard micronucleus study, and there was no positive control.

Data source

Reference

Reference Type:

study report

Title:

Unnamed

Year:

1991

Report date:

1991

Materials and methods

Test guideline

Qualifier:

according to guideline

Guideline:

other: OECD 413

Deviations:

no

Principles of method if other than guideline:

Micronucleus data were gathered as part of a 14-day repeated-dose inhalation study, no positive control was included.

GLP compliance:

yes

Type of assay:

micronucleus assay

Test material

Test material information

Constituent 1

Reference substance name:

Dimethoxymethylphenylsilane

EC Number:

221-192-4

EC Name:

Dimethoxymethylphenylsilane

Cas Number:

3027-21-2

Molecular formula:

C9H14O2Si

Test animals

Species:

rat

Strain:

Sprague-Dawley

Sex:

male/female

Details on test animals or test system and environmental conditions:

TEST ANIMALS

- Source: not stated

- Age at study initiation: 5 - 7 weeks

- Weight at study initiation: 100 - 160 g

- Assigned to test groups randomly: yes, under following basis: using Xybion ASLECT program

- Housing: suspended, steel, wire mesh bottom cages.

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

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

ENVIRONMENTAL CONDITIONS

- Temperature (°F): 68 - 73 °F

- Humidity (%): 30 - 70 %

- Air changes (per hr): 12 - 15

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

Administration / exposure

Route of administration:

inhalation: vapour

Details on exposure:

TYPE OF INHALATION EXPOSURE: whole body

GENERATION OF TEST ATMOSPHERE / CHAMBER DESCRIPTION

- Exposure apparatus: 450 litre stainless steel whole body exposure chambers

- Source and rate of air: filtered room air

- Method of conditioning air: filtered with hepa and charcoal filters

- System of generating particulates/aerosols: test material introduced into chambers via special designed glass J-tubes, metered with FMI lab pumps. Glass beads and heating tape were used to help vaporize the test material.

- Air change rate: 12 - 15 air changes per hour

Duration of treatment / exposure:

Six hours/day

Frequency of treatment:

daily, 5 days a week for 2 weeks.

Post exposure period:

None

Doses / concentrations

Dose / conc.:

50 ppm (nominal)

No. of animals per sex per dose:

5

Control animals:

yes, concurrent no treatment

Positive control(s):

none

Examinations

Tissues and cell types examined:

Bone marrow

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 cells were fixed in methanol for 5 minutes.

METHOD OF ANALYSIS: microscopic examination. 2000 PCE scored for the incidence of polychromatic erythrocytes with micronuclei.

Statistics:

% Micronucleated PCE'S mean of 2000 per animal and mean ratio of PCE:NCE calculated with standard deviation. Data was analysed by a two-sided Welch trend test. If a significant overall trend was detected, then all follow up tests were one-sided and in the same direction as the overall trend. All tests were conducted at the 0.05 level of significance.

Results and discussion

Test results

Key result

Sex:

male/female

Genotoxicity:

negative

Toxicity:

yes

Remarks:

reduction in PCE:NCE ratio relative to control

Vehicle controls validity:

valid

Negative controls validity:

valid

Positive controls validity:

not examined

Any other information on results incl. tables

Table 3: Results of in vivo micronucleus test with Dow X2-2614

Exposure concentration (ppm)		0	50
Number of cells evaluated		2000	2000
Sampling time (d)		14 d	14 d
Number of erythrocytes	normo­chromatic	NR	NR
	poly­chromatic	2000	2000
	% Micronucleated PCE’S (mean of 2000 per animal)	Male  0.07 Female 0.15	Male 0.12 Female 0.05
Ratio of erythro­cytes	polychromatic / normochromatic	Male 1.8 Female 3.28	Male 1.12 Female 0.98
	polychromatic with micro­nuclei / normochromatic	NR	NR

 

Applicant's summary and conclusion

Conclusions:

The substance was tested in an in vivo micronucleus assay in rat (performed as part of a 14-day repeat dose inhalation toxicity study to OECD 413 and in compliance with GLP. It was not genotoxic under the conditions of the test.