Trichloro(ethyl)silane

Genetic toxicity: in vitro

Administrative data

Endpoint:

in vitro cytogenicity / chromosome aberration study in mammalian cells

Remarks:

Type of genotoxicity: chromosome aberration

Type of information:

migrated information: read-across from supporting substance (structural analogue or surrogate)

Adequacy of study:

key study

Reliability:

2 (reliable with restrictions)

Rationale for reliability incl. deficiencies:

other: see 'Remark'

Remarks:

The study was conducted according to a test protocol that is comparable to the appropriate OECD test guideline, with restrictions. The restrictions are that only 100 cells evaluated and the reporting differed from the current guideline. It was not compliant with GLP. It is considered that read across to the registered substance is scientifically justified.

Data source

Reference

Reference Type:

study report

Title:

Unnamed

Year:

1978

Report date:

1978

Materials and methods

Test guideline

Qualifier:

equivalent or similar to guideline

Guideline:

OECD Guideline 473 (In Vitro Mammalian Chromosome Aberration Test)

Deviations:

yes

Remarks:

only 50 cells scored for aberrations, reporting has less detail than current guideline

Principles of method if other than guideline:

Litton Bionetics standard procedure: Screening Program for the Identification of Potential Mutagens and Carcinogens. Protocol Number: DMT 100

GLP compliance:

no

Type of assay:

in vitro mammalian chromosome aberration test

Test material

Test material information

Constituent 1

Reference substance name:

Trichloro(methyl)silane

EC Number:

200-902-6

EC Name:

Trichloro(methyl)silane

Cas Number:

75-79-6

IUPAC Name:

trichloro(methyl)silane

Method

Species / strain

Species / strain / cell type:

mouse lymphoma L5178Y cells

Metabolic activation:

with and without

Metabolic activation system:

mouse liver S9

Test concentrations with justification for top dose:

0.02, 0.04, 0.08, 0.16, and 0.32 µl/ml, equivalent to approximately 20, 40, 80, and 160 µg/ml

Vehicle / solvent:

- Vehicle(s)/solvent(s) used: ethanol

- Justification for choice of solvent/vehicle: It is assumed by the reviewer that the solvent was chosen based on solubility properties and relative non-toxicity to bacteria

Controls

Controls 1

Untreated negative controls:

yes

Remarks:

Medium

Negative solvent / vehicle controls:

yes

True negative controls:

no

Positive controls:

yes

Positive control substance:

ethylmethanesulphonate

Remarks:

(without activation)

Controls 2

Untreated negative controls:

yes

Remarks:

Medium

Negative solvent / vehicle controls:

yes

True negative controls:

no

Positive controls:

yes

Positive control substance:

N-dimethylnitrosamine

Remarks:

(with activation)

Details on test system and experimental conditions:

METHOD OF APPLICATION: in medium

DURATION
- Exposure time: 4 hours

- Expression time (cells in growth medium): 20 hours

NUMBER OF REPLICATIONS: 1 plates for each test concentration

NUMBER OF CELLS EVALUATED: 50 per plate

DETERMINATION OF CYTOTOXICITY

- Method: mitotic index

Results and discussion

Test results

Species / strain:

mouse lymphoma L5178Y cells

Metabolic activation:

with and without

Genotoxicity:

ambiguous

Cytotoxicity / choice of top concentrations:

other: >= 0.16 µl/ml (equivalent to approximately 160 µg/ml)

Vehicle controls validity:

valid

Untreated negative controls validity:

valid

Positive controls validity:

valid

Remarks on result:

other: all strains/cell types tested

Remarks:

Migrated from field 'Test system'.

Any other information on results incl. tables

Table 2: Cytogenetic analysis (without activation)

Concentration µg/ml*	Total No. Of Cells	Type / Frequency Aberrations per Cell (%)	No. Of Cells with 2+ Aberrations (%)	Mitotic Index (%)
Negative Control	50	1tb	0	2.2
Solvent Control	50	0	0	13.8
Positive Control	50	6tb, 1f, 1t, 6qr, 5tr, 1min	4	7.4
10	50	1qr	0	7.4
20	50	0	0	4.6
40	50	1f	0	5.2
80	50	1af, 1tb	0	8.4
160	50	0	0	5.4

 * Concentrations given in report as µl/ml - converted by reviewer

Table 3: Cytogenetic analysis (with activation)

Compound and Concentration µg/ml*	Total No. Of Cells	Type / Frequency Aberrations per Cell (%)	No. Of Cells with 2+ Aberrations (%)	Mitotic Index (%)
Negative Control	50	1tb, 1>	0	4
Solvent Control	50	0	0	9
Positive Control	50	6tb, 1f, 2t, 1tr, 1qr	1	4.4
20	50	1tb	0	4.4
40	50	2t, 1tr	1	10.8
80	50	1tb, 3f, 1tr	2	8
160	50	1tb, 1f, 1af, 1t	1	7.8
320	50	0	0	10.4

 * Concentrations given in report as µl/ml - converted by reviewer

Key to type of aberration

tb	Chromatidbreak
f	Fragment
qr	Quadriradial
tr	Triradial
min	Minute chromosome
af	Acentricfragment
t	Translocation

 

Applicant's summary and conclusion

Conclusions:

Interpretation of results (migrated information):
positive with metabolic activation not dose related
negative without metabolic activation

Trichloro(methyl)silane has been tested in a reliable assay according to a protocol that is similar to OECD TG 476. Appropriate concurrent negative and positive controls were included and the expected responses were observed. The number of cells with 2 or more aberrations increased very slightly under activation conditions, and no increase was observed at the highest dose tested. Trimethylchlorosilane was considered by the authors of the study to have weak clastogenic activity that may be related to the cytotoxic properties of the test substance. It is concluded by the reviewer that the study does not demonstrate a biologically relevant effect.