Dichloro(diphenyl)silane

Endpoint summary

Key value for chemical safety assessment

Genetic toxicity in vitro

Description of key information

In vitro:
Gene mutation (Bacterial reverse mutation assay / Ames test): negative with and without activation in Salmonella typhimurium strains TA 98, TA 100, TA 1535 and TA 1537 and E. coli WP2 (similar to OECD TG 471).

Mammalian cytogenicity (Chinese hamster lung fibroblasts V79 cell chromosome aberration assay): negative with and without metabolic activation (according to OECD TG 473).

Mammalian cell gene mutation:

No measured data are available to assess the in vitro mammalian mutagenicity potential of the registered substance, however, reliable data are available for the structural analogue substance trichloro(phenyl)silane (CAS 98-13-5).

negative in L5178Y mouse lymphoma cells with the structural analogue substance trichloro(phenyl)silane (CAS 98 -13 -5) (according to OECD TG 476).

Link to relevant study records

Reference

Reference 1

Endpoint:

in vitro gene mutation study in bacteria

Type of information:

experimental study

Adequacy of study:

key study

Study period:

30 Apr - 14 Nov 1994

Reliability:

2 (reliable with restrictions)

Rationale for reliability incl. deficiencies:

comparable to guideline study with acceptable restrictions

Remarks:

the range of strains does not comply with the current guideline

Qualifier:

equivalent or similar to guideline

Guideline:

OECD Guideline 471 (Bacterial Reverse Mutation Assay)

Version / remarks:

July 1997

Deviations:

yes

Remarks:

Did not include strain to detect cross-linking mutagens.

GLP compliance:

yes

Type of assay:

bacterial reverse mutation assay

Target gene:

His operon

Species / strain / cell type:

S. typhimurium TA 1535, TA 1537, TA 98 and TA 100

Additional strain / cell type characteristics:

other: rfa, uvrB and pKM101 (TA98 & TA100)

Metabolic activation:

with and without

Metabolic activation system:

cofactor supplemented post-mitochondrial fraction (S9 mix), prepared from the livers of rats treated with Aroclor 1254

Test concentrations with justification for top dose:

8-5000 µg/plate - Plate incorporation method.
31.25-1200 µg/plate - Pre-incubation method.

Vehicle / solvent:

- Vehicle/solvent used: Ethylene glycol dimethylether (EGDE, dryed with a molcular sieve, 0.4 nm)

Untreated negative controls:

no

Negative solvent / vehicle controls:

yes

True negative controls:

no

Positive controls:

yes

Positive control substance:

sodium azide

other: nitrofurantoin (NF), 4-nitro-1,2-phenyl diamine (4-NPDA), 2-aminoanthracene (2-AA)

Details on test system and experimental conditions:

METHOD OF APPLICATION: in agar (plate incorporation) and preincubation;

DURATION
- Preincubation period: 30 minutes
- Exposure duration: 48 hours

NUMBER OF REPLICATIONS: in 2 independent experiments
- Number of cultures per concentration: quadruplicates
- Number of independent experiments: 2 for strain TA 98, TA 100 and TA 1537; 5 for strain TA 1535

DETERMINATION OF CYTOTOXICITY
- Method: Gross appraisal of background growth on the plate, marked or dose-dependent reduction in the mutant count per plate compared to the negative controls and the titer was determined.


Metabolic activation system: It was made from the livers of at least six adult male Sprague-Dawley rats, of approximately 200 to 300 g in weight. For enzyme induction, the animals received a single intraperitoneal injection of Aroclor 1254, dissolved in corn oil, at a dose of 500 mg/kg bw, five days prior to sacrifice. The S9 mix also contained seventy mL of cofactor solution containing the following:

-MgCl2 x 6H2O (162.6 mg)
-KCl (246.0 mg)
-Glucose-6-phophate, disodium salt (179.1 mg)
-NADP, disodium salt (315.0 mg)
-Phosphate buffer (100.0 mg)

Evaluation criteria:

A reproducible and dose-related increase in mutant counts of at least one strain is considered to be a positive result. For TA 1535, TA 100 and TA 98 this increase should be about twice that of negative controls, whereas TA 1537, at least a threefold increase should be reached. However, these guidelines may be overruled by good scientific judgement.

Acceptance criteria
a) The negative controls had to be within the expected range, as defined by published data and/or the laboratories own historical control data.
b) The positive controls had to show sufficient effects, as defined by the laboratories' experience.
c) Titer determinations had to demonstrate sufficient bacterial density in the suspension.
Onlyl trials which complied with all three of the above criteria were accepted for assessment. Even if the criteria for points b) and c) were not met, a trial was accepted, if it showed mutagenic activity of the test substance.

Species / strain:

S. typhimurium TA 1537

Metabolic activation:

with and without

Genotoxicity:

negative

Cytotoxicity / choice of top concentrations:

cytotoxicity

Vehicle controls validity:

valid

Untreated negative controls validity:

not examined

True negative controls validity:

not examined

Positive controls validity:

valid

Species / strain:

S. typhimurium TA 1535

Metabolic activation:

with and without

Genotoxicity:

negative

Cytotoxicity / choice of top concentrations:

cytotoxicity

Vehicle controls validity:

valid

Untreated negative controls validity:

not examined

True negative controls validity:

not examined

Positive controls validity:

valid

Species / strain:

S. typhimurium TA 100

Metabolic activation:

with and without

Genotoxicity:

negative

Cytotoxicity / choice of top concentrations:

cytotoxicity

Vehicle controls validity:

valid

Untreated negative controls validity:

not examined

True negative controls validity:

not examined

Positive controls validity:

valid

Species / strain:

S. typhimurium TA 98

Metabolic activation:

with and without

Genotoxicity:

negative

Cytotoxicity / choice of top concentrations:

cytotoxicity

Vehicle controls validity:

valid

Untreated negative controls validity:

not examined

True negative controls validity:

not examined

Positive controls validity:

valid

Additional information on results:

ADDITIONAL INFORMATION ON CYTOTOXICITY: The salmonella/ microsome plate incorporation test, employing doses of up to 5000 µg per plate, showed the test substance to produce bacterial toxic effects at 40 µg per plate and above. Therefore, 5000 µg per plate could not be used for assessment. The salmonella/ microsome test, using preincubation for 30 minutes at 37 °C and employing doses of up to 1200 µg per tube, showed the test substance to produce bacterial toxic effects at 100 µg per tube and above.

Table 1. Summary of mean values without S9 mix.

Groups	Strain
	TA 1535	TA 100	TA 1537	TA 98
Plate incorporation method (µg/plate)
0	25	120	12	23
8	26	116	9	24
40	27	117	11	24
200	31	104	9	23
1000	30	105	8	29
5000	B	B	B	B
Na-azide	926	-	-	-
NF	-	378	-	-
4-NPDA	-	-	101	118
Pre-incubation method- µg/plate
0	22	143	13	31
31.25	29	146	13	31
62.5	36	157	14	31
125	30	166	15	28
250	43	134	8B	27
500	38B	144	6B	22B
1000	32B	117B	6B	17B
Na-azide	897	-		-
NF	-	531	-	-
4-NPDA	-	-	83	60

NF: nitrofurantonin;

4-NPDA: 4-nitro-1,2-phenyl diamine

B: Background lawn reduced

Table 2. Summary of mean values with S9 mix.

Groups	Strain
	TA 1535	TA 100	TA 1537	TA 98
Plate incorporation method (µg/plate)
0	21	150	16	42
8	19	146	12	44
40	18	142*	14	42*
200	17*	119*	12	39*
1000	16*	119B*	12*	34*
5000	B*	B*	B*	B*
2-AA	211	1476	117	891
Pre-incubation method (µg/plate)
0	17	141	10	40
31.25	17	151	12	38
62.5	17	148	13	46
125	22	166	11	45
250	19	154	11	48
500	21	168	11	41
1000	19B*	119B*	7B*	36B*
2-AA	213	1268	126	1107

2-AA: 2-aminoanthracene

B: Background lawn reduced

*: Bacteriotoxic effect (based on titer determination; studied on two plates for each concentration with S9 mix)

Table 3. Summary of mean values for TA 1535 without S9 mix.

Pre-incubation method µg/plate	Strain
	TA 1535	TA 1535	TA 1535
0	27	29
31.25	30	22
62.5	32	29
125	31	31
250	51	35
500	33B*	52B*
1000	40B*	55B*
Na-azide	883	848
0	12	15	12
100	15*	19	12
200	19*	18*	13*
400	20*	15*	11*
600	17B*	17B*	10B*
800	15B*	8B*	7B*
1000	11B*	9B*	10B*
1200	8B*	10B*	7B*
Na-azide	855	639	648
0	11	11	18
100	11	14	16
200	11	12	17
400	13	12	15
600	10	13	11
800	9	12	10
1000	10	11	9
1200	10*	12*	10*
Na-azide	714	700	678

B: Background lawn reduced

*: Bacteriotoxic effect (based on titer determination; studied on two plates for each concentration without S9 mix)

Plate incorporation method:

There was no indication of a bacterial toxic effect of the test substance at 8 µg per plate. The total bacterial counts consistently produced results comparable to the negative controls, or differed only insignificantly (Table 1 and 2). No inhibition of growth was noted as well. None of the four strains concerned showed a dose-related and biologically relevant increase in mutant counts over those of the negative controls. This applied both to the tests with and without S9-mix.

Pre-incubation method:

There was no indication of a bacterial toxic effect of the test substance at doses of up to and including 62.5 µg per tube. The total bacteria counts consistently produced results comparable to the negative controls, or differed only insignificantly (Table 1 and 2). No inhibition of growth was noted as well. One of the four strains concerned revealed an increase in mutant counts to double those of negative controls. Strains TA 1535 were affected without metabolic activation (Table 1). This increase did, however, not correlate with dose and could not be confirmed (Table 3). Therefore, it was considered to be of no relevance.

The positive controls sodium azide, nitrofurantonin, 4-nitro-1,2-phenyl diamine and 2-aminoanthracene increased mutant counts well over those of the negative controls, and thus demonstrated the system’s sensitivity and the activity of the S9 mix.

Conclusions:

Interpretation of results: negative with and without metabolic activation

In a bacterial mutagenicity assay according to OECD 471 and GLP, no indications of mutagenic effects of dichloro(diphenyl)silane was found at assessable doses of up to 1200 µg per plate in any of the Salmonella typhimurium strains used in the plate incorporation assay and in the preincubation assay.

Reference 2

Endpoint:

in vitro gene mutation study in bacteria

Type of information:

experimental study

Adequacy of study:

key study

Study period:

03 - 06 May 1985

Reliability:

2 (reliable with restrictions)

Rationale for reliability incl. deficiencies:

guideline study with acceptable restrictions

Remarks:

Plate incorporation only, apparently no replicates, no confirmation experiment of negative results

Qualifier:

equivalent or similar to guideline

Guideline:

OECD Guideline 471 (Bacterial Reverse Mutation Assay)

Version / remarks:

July 1997

Deviations:

yes

Remarks:

plate incorporaton only, apparently no replicates, no confirmation experiment of negative results

GLP compliance:

yes

Type of assay:

bacterial reverse mutation assay

Target gene:

his operon (for S. typhimurium strains) and trp operon (for E. coli strains)

Species / strain / cell type:

E. coli WP2

Species / strain / cell type:

S. typhimurium TA 1535, TA 1537, TA 98 and TA 100

Metabolic activation:

with and without

Metabolic activation system:

cofactor supplemented post-mitochondrial fraction (S9 mix), prepared from the livers of rats treated with Aroclor 1254

Test concentrations with justification for top dose:

0.078-1.25 µg/plate

Vehicle / solvent:

- Vehicle/solvent used: ethanol

Untreated negative controls:

no

Negative solvent / vehicle controls:

yes

True negative controls:

no

Positive controls:

yes

Positive control substance:

4-nitroquinoline-N-oxide

sodium azide

other: 2-Anthramine (ANTH), 2-Aminofluorene (AF), Daunomycin (D), N-Methyl-N-nitro-N-nitrosoquanidine (MNNG)

Details on test system and experimental conditions:

METHOD OF APPLICATION: in agar (plate incorporation).

DURATION
- Exposure duration: 72 hours


NUMBER OF REPLICATIONS: 1 experiment


DETERMINATION OF CYTOTOXICITY
- Method: not reported

Evaluation criteria:

Not reported

Statistics:

Not reported

Species / strain:

S. typhimurium TA 100

Metabolic activation:

with and without

Genotoxicity:

negative

Cytotoxicity / choice of top concentrations:

cytotoxicity

Remarks:

1.25 µg/plate

Vehicle controls validity:

valid

Untreated negative controls validity:

not examined

True negative controls validity:

not examined

Positive controls validity:

valid

Species / strain:

S. typhimurium TA 1535

Metabolic activation:

with and without

Genotoxicity:

negative

Cytotoxicity / choice of top concentrations:

cytotoxicity

Remarks:

1.25 µg/plate

Vehicle controls validity:

valid

Untreated negative controls validity:

not examined

True negative controls validity:

not examined

Positive controls validity:

valid

Species / strain:

S. typhimurium TA 1537

Metabolic activation:

with and without

Genotoxicity:

negative

Cytotoxicity / choice of top concentrations:

cytotoxicity

Remarks:

1.25 µg/plate

Vehicle controls validity:

valid

Untreated negative controls validity:

not examined

True negative controls validity:

not examined

Positive controls validity:

valid

Species / strain:

S. typhimurium TA 98

Metabolic activation:

with and without

Genotoxicity:

negative

Cytotoxicity / choice of top concentrations:

cytotoxicity

Remarks:

1.25 µg/plate

Vehicle controls validity:

valid

Untreated negative controls validity:

not examined

True negative controls validity:

not examined

Positive controls validity:

valid

Species / strain:

E. coli WP2

Metabolic activation:

with and without

Genotoxicity:

negative

Cytotoxicity / choice of top concentrations:

cytotoxicity

Remarks:

1.25 µg/plate

Vehicle controls validity:

valid

Untreated negative controls validity:

not examined

True negative controls validity:

not examined

Positive controls validity:

valid

Additional information on results:

ADDITIONAL INFORMATION ON CYTOTOXICITY: Concentrations of test material above 1.25 µg/plate were toxic to the tester strains.

Table 1. Overlay plate test results:

Test	Revertants per plate
	TA 1535	TA 1537	TA 98	TA 100	WP2
Non-Activation (-S9)
Solvent control	29	9	22	94	36
Positive control*	125	152	169	532	124
Test Material (µg/plate)
0.078	23	10	19	98	42
0.156	22	7	18	126	37
0.312	17	6	16	84	37
0.625	11	8	22	120	28
1.250	14	9	24	132	24
Activation (+S9)
Solvent control	17	8	58	100	17
Positive control**	171	168	1074	1045	251
Test Material (µg/plate)
0.078	13	12	49	98	18
0.156	15	8	58	94	17
0.312	16	12	51	114	19
0.625	12	12	50	121	17
1.250	13	14	43	88	20

*TA 1535: AZ (10 µg/plate)         ** TA 1535: ANTH (10 µg/plate)         

*TA 1537: NQNO (10 µg/plate)      ** TA 1537: AF (10 µg/plate)         

*TA 98: D (10 µg/plate)                   ** TA 98: AF (10 µg/plate)         

*TA 100: AZ (10 µg/plate)             **TA 100: AF (10 µg/plate)         

*WP2: MNNG (10 µg/plate)           **WP2: ANTH (10 µg/plate)        

Solvent: Dimethylsulfoxide (50 µg/plate)         

Conclusions:

Interpretation of results: negative with and without metabolic activation.

In a bacterial mutagenicity assay according to OECD 471 and GLP, the test material failed to exhibit mutagenic activity in both the activation and non-activation systems and is considered not to be mutagenic under the conditions employed.

Reference 3

Endpoint:

in vitro cytogenicity / chromosome aberration study in mammalian cells

Type of information:

experimental study

Adequacy of study:

key study

Study period:

20 Jul - 13 Dec 2011

Reliability:

1 (reliable without restriction)

Rationale for reliability incl. deficiencies:

guideline study

Qualifier:

according to guideline

Guideline:

OECD Guideline 473 (In Vitro Mammalian Chromosome Aberration Test)

Deviations:

no

Qualifier:

according to guideline

Guideline:

EPA OPPTS 870.5375 - In vitro Mammalian Chromosome Aberration Test

Deviations:

no

Qualifier:

according to guideline

Guideline:

EU Method B.10 (Mutagenicity - In Vitro Mammalian Chromosome Aberration Test)

Deviations:

no

GLP compliance:

yes (incl. QA statement)

Remarks:

Bayerisches Landesamt für Gesundheit und Lebensmittelsicherheit, München, Germany

Type of assay:

in vitro mammalian chromosome aberration test

Species / strain / cell type:

Chinese hamster lung fibroblasts (V79)

Details on mammalian cell type (if applicable):

- Type and identity of media: MEM
- Properly maintained: yes
- Periodically checked for Mycoplasma contamination: yes

Metabolic activation:

with and without

Metabolic activation system:

cofactor supplemented post-mitochondrial fraction (S9 mix), prepared from the livers of Wistar rats treated with phenobarbital and ß-naphthoflavone

Test concentrations with justification for top dose:

Pre-experiment:
with and without metabolic activation:
0.020, 0.039, 0.078, 0.156, 0.313, 0.625, 1.25, 2.5, 5 and 10 mM

Experiment I:
without metabolic activation:
0.7, 0.9 and 1.1 mM

with metabolic activation:
0.625, 1.25 and 2.5 mM

Experiment II:
without metabolic activation:
0.30, 0.45 and 0.60 mM

with metabolic activation:
1.5, 2.0 and 2.5 mM

Vehicle / solvent:

-Vehicle/solvent used: cell culture medium (MEM)
- Justification for choice of solvent/vehicle: Due to the nature of the test item it was suspended in cell culture medium (MEM). The solvent was compatible with the survival of the cells and the S9 activity.

Untreated negative controls:

yes

Negative solvent / vehicle controls:

no

True negative controls:

no

Positive controls:

yes

Positive control substance:

cyclophosphamide

ethylmethanesulphonate

Details on test system and experimental conditions:

TREATMENT TIME:
4 hours (Experiment I with and without metabolic activation, experiment II with metabolic activation)
20 hours (Experiment II without metabolic activation)

FIXATION INTERVAL: 20 hours (Experiment I and II with and without metabolic activation)
NUMBER OF REPLICATIONS: 2 independent experiments
NUMBER OF CELLS SEEDED: 1 x 10^4 - 5 x 10^4 cells
NUMBER OF CULTURES: two cultures per concentration
NUMBER OF CELLS SCORED: 200 cells per concentration (100 cells per culture),
except for concentration 2.5 mM (experiment II with metabolic activation): 112 for the 1st and 100 for the 2nd culture.
DETERMINATION OF CYTOTOXICITY: Mitotic index, cell density

Evaluation criteria:

There are several criteria for determining a positive result:
- a clear and dose-related increase in the number of cells with aberrations,
- a biologically relevant response for at least one of the dose groups, which is higher than the laboratory negative control range (0.0% - 4.0% aberrant cells (with and without metabolic activation)).

Statistics:

According to OECD guidelines, the biological relevance of the results is the criterion for the interpretation of results, a statistical evaluation of the results is not regarded as necessary.

Species / strain:

Chinese hamster lung fibroblasts (V79)

Metabolic activation:

with and without

Genotoxicity:

negative

Cytotoxicity / choice of top concentrations:

cytotoxicity

Vehicle controls validity:

not applicable

Untreated negative controls validity:

valid

True negative controls validity:

not applicable

Positive controls validity:

valid

Results of chromosome analysis
without metabolic activation
		Cytotoxicity	Chromatid aberrations				Isochromatid aberrations				rel. Mitotic index (%)	rel. Cell density (%)	Poly-ploidy	mean % aberrant cells
	Scored cells		gaps	breaks	inter-changes	other	gaps	breaks	inter-changes	other				incl. Gaps	excl. Gaps
Experiment I
negative control	200	-	2	1	1	1	0	0	1	0	100	100	0	2.5	1.5
0.25 mM	-	no	n.d.	n.d.	n.d.	n.d.	n.d.	n.d.	n.d.	n.d.	122	n.d.	n.d.	n.d.	n.d.
0.5 mM	-	no	n.d.	n.d.	n.d.	n.d.	n.d.	n.d.	n.d.	n.d.	106	n.d.	n.d.	n.d.	n.d.
0.7 mM	200	no	3	1	0	0	0	0	0	0	104	93	1	2.0	0.5
0.9 mM	200	no	2	0	0	1	0	0	0	0	73	75	0	1.5	0.5
1.1 mM	200	yes	6	2	0	1	0	0	1	0	47	66	1	4.0	1.5
1.3 mM	-	yes	n.d.	n.d.	n.d.	n.d.	n.d.	n.d.	n.d.	n.d.	0	n.d.	n.d.	n.d.	n.d.
1.5 mM	-	yes	n.d.	n.d.	n.d.	n.d.	n.d.	n.d.	n.d.	n.d.	0	n.d.	n.d.	n.d.	n.d.
EMS (600 mg/mL)	200	-	5	11	5	3	0	0	1	0	101	91	0	11.0	9.0
Experiment II
negative control	200	-	1	0	0	0	0	0	2	0	100	100	0	1.5	1.0
0.10 mM	-	no	n.d.	n.d.	n.d.	n.d.	n.d.	n.d.	n.d.	n.d.	97	n.d.	n.d.	n.d.	n.d.
0.30 mM	200	no	2	3	0	0	1	0	0	0	83	98	1	3.0	1.5
0.45 mM	200	no	2	0	1	0	0	0	1	0	71	98	0	2.0	1.0
0.60 mM	200	yes	0	2	0	1	1	0	1	0	44	85	1	2.5	2.0
0.75 mM	-	yes	n.d.	n.d.	n.d.	n.d.	n.d.	n.d.	n.d.	n.d.	0	n.d.	n.d.	n.d.	n.d.
EMS (400 µg/mL)	200	-	0	12	5	0	1	0	1	1	54	98	1	8.5	8.0
Results of chromosome analysis
with metabolic activation
		Cytotoxicity	Chromatid aberrations				Isochromatid aberrations				rel. Mitotic index (%)	rel. Cell density (%)	Poly-ploidy	mean % aberrant cells
	Scored cells		gaps	breaks	inter-changes	other	gaps	breaks	inter-changes	other				incl. Gaps	excl. Gaps
Experiment I
negative control	200	-	6	3	0	0	0	0	0	0	100	100	5	4.5	1.5
0.156 mM	-	no	n.d.	n.d.	n.d.	n.d.	n.d.	n.d.	n.d.	n.d.	96	n.d.	n.d.	n.d.	n.d.
0.313 mM	-	no	n.d.	n.d.	n.d.	n.d.	n.d.	n.d.	n.d.	n.d.	92	n.d.	n.d.	n.d.	n.d.
0.625 mM	200	no	4	1	0	1	1	0	0	0	92	109	0	3.5	1.0
1.25 mM	200	no	1	3	0	0	1	0	0	0	104	94	0	2.5	1.5
2.5 mM	200	yes	3	3	0	0	0	0	0	0	47	97	1	3.0	2.0
5 mM	-	yes	n.d.	n.d.	n.d.	n.d.	n.d.	n.d.	n.d.	n.d.	n.d.	n.d.	n.d.	n.d.	n.d.
10 mM	-	yes	n.d.	n.d.	n.d.	n.d.	n.d.	n.d.	n.d.	n.d.	n.d.	n.d.	n.d.	n.d.	n.d.
CPA (0.83 µg/mL)	200	-	7	10	3	4	0	0	0	0	82	87	1	11.5	8.5
Experiment II
negative control	200	-	4	2	0	0	0	0	0	0	100	100	1	3.0	1.0
0.75 mM	-	no	n.d.	n.d.	n.d.	n.d.	n.d.	n.d.	n.d.	n.d.	95	n.d.	n.d.	n.d.	n.d.
1.0 mM	-	no	n.d.	n.d.	n.d.	n.d.	n.d.	n.d.	n.d.	n.d.	91	n.d.	n.d.	n.d.	n.d.
1.5 mM	200	no	3	1	0	0	0	0	0	0	87	110	1	2.0	0.5
2.0 mM	200	yes	2	3	0	0	0	0	1	0	41	111	2	3.0	2.0
2.5 mM	212	yes	3	4	0	2	0	0	0	0	32	45	1	4.2	2.8
3.0 mM	-	yes	n.d.	n.d.	n.d.	n.d.	n.d.	n.d.	n.d.	n.d.	10	n.d.	n.d.	n.d.	n.d.
3.5 mM	-	yes	n.d.	n.d.	n.d.	n.d.	n.d.	n.d.	n.d.	n.d.	15	n.d.	n.d.	n.d.	n.d.
4.0 mM	-	yes	n.d.	n.d.	n.d.	n.d.	n.d.	n.d.	n.d.	n.d.	0	n.d.	n.d.	n.d.	n.d.
5.0 mM	-	yes	n.d.	n.d.	n.d.	n.d.	n.d.	n.d.	n.d.	n.d.	0	n.d.	n.d.	n.d.	n.d.
CPA (0.83 µg/mL)	200	-	12	13	5	1	0	0	0	0	88	104	1	11.5	8.0

n.d. not determined

 

Conclusions:

Interpretation of results: negative with and without metabolic activation

In conclusion, it can be stated that during the described in vitro chromosomal aberration test and under the experimental conditions reported, the test item did not induce structural chromosomal aberrations in the V79 Chinese hamster cell line.
Therefore, the test item Dichloro(diphenyl)silane is considered to be non-clastogenic in this chromosome aberration test.

Executive summary:

To investigate the potential of the test substance to induce structural chromosome aberrations in Chinese hamster V79 cells, an in vitro chromosome aberration assay was carried out.

The chromosomes were prepared 20 h after start of treatment with the test item. The treatment interval was 4 h with and without metabolic activation in experiment I. In experiment II, the treatment interval was 4 h with and 20 h without metabolic activation. Duplicate cultures were treated at each concentration. 100 metaphases per culture were scored for structural chromosomal aberrations (except for concentration 2.5 mM (experiment II with metabolic activation): 112 for the 1st and 100 for the 2nd culture.)

Due to the nature of the test item it was suspended in cell culture medium (MEM). The solvent was compatible with the survival of the cells and the S9 activity.

The following concentrations were evaluated for the microscopic analysis of chromosomal aberrations:

Experiment I:

without metabolic activation: 0.7, 0.9 and 1.1 mM

with metabolic activation: 0.625, 1.25 and 2.5 mM

Experiment II:

without metabolic activation: 0.30, 0.45 and 0.60 mM

with metabolic activation: 1.5, 2.0 and 2.5 mM

In the experiments without metabolic activation no precipitation of the test item was noted after incubation with the test item at the concentrations evaluated, with metabolic activation precipitation of the test item was noted at a concentration of 2.5 mM in experiment I and 1.5 mM in experiment II.

In experiment I without metabolic activation, toxic effects of the test item were noted at a concentration of 1.1 mM, with metabolic activation at a concentration of 2.5 mM.

In experiment II without metabolic activation, toxic effects of the test item were observed at a concentration of 0.60 mM. With metabolic activation toxic effects of the test item were noted at concentrations of 2.0 mM and higher.

In experiment I and II no biologically relevant increase of the aberration rates was noted after treatment with the test item with and without metabolic activation. The aberration rates of all dose groups treated with the test item were within the historical control data of the negative control.

In both experiments with and without metabolic activation no biologically relevant increase in the frequencies of polyploid cells was found after treatment with the test item as compared to the controls.

EMS (400 and 600 µg/mL) and CPA (0.83 µg/mL) were used as positive controls and induced distinct and biologically relevant increases in cells with structural chromosomal aberrations.

The positive controls induced the appropriate responses.

There was no evidence of test item induced over background.

This study is classified as acceptable. This study satisfies the requirement for Test Guideline OPPTS 870.5375; OECD 473 for in vitro cytogenetic mutagenicity data. 

Reference 4

Endpoint:

in vitro gene mutation study in mammalian cells

Type of information:

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

Adequacy of study:

key study

Justification for type of information:

Please refer to the attached justification below and the overall justification for grouping of substances attached in IUCLID Section 13.

Reason / purpose for cross-reference:

read-across source

Species / strain:

mouse lymphoma L5178Y cells

Metabolic activation:

with and without

Genotoxicity:

negative

Cytotoxicity / choice of top concentrations:

cytotoxicity

Remarks:

900 µg/ml

Vehicle controls validity:

valid

Untreated negative controls validity:

not applicable

Positive controls validity:

valid

Conclusions:

Interpretation of results: negative with and without activation

The structural analogue substance trichloro(phenyl)silane (CAS: 98-13-5) was tested in a reliable study according to OECD TG 476 and under GLP. No increase in mutant frequency was observed at any concentration with and without activation (4 hours treatment) and without activation (24 hours treatment). Expected results were obtained with positive and negative controls. It is concluded that trichloro(phenyl)silane and thus dichloro(diphenyl)silane are negative for the induction of mutations in L5178Y cells under the conditions of the test.

Endpoint conclusion

Endpoint conclusion:

no adverse effect observed (negative)

Genetic toxicity in vivo

Endpoint conclusion

Endpoint conclusion:

no study available

Additional information

A key bacterial reverse mutation assay similar to OECD TG 471 and GLP is available for dichloro(diphenyl)silane. No evidence for a test-substance related increase in the number of revertants was observed in Salmonella typhimurium strains TA 98, TA 100, TA 1535, and TA 1537. The strains were treated with doses of up to 1200 µg/plate with and without metabolic activation system. Cytotoxic effects of the test substance were noted starting at 40 µg/plate. Appropriate positive and solvent controls were included and gave expected results. Under the conditions of this study, dichloro(diphenyl)silane was concluded to be non-mutagenic in the Salmonella typhimurium strains tested (Bayer AG, 1994).

An additional key bacterial reverse mutation assay with the registered substance is also available. In that study, there was no evidence for a test-substance related increase in the number of revertants observed in Salmonella typhimurium strains TA 98, TA 100, TA 1535, TA 1537 and Escherichia coli WP2 strain. The strains were treated with doses of 0.078 to 1.25 µg/plate with and without metabolic activation system. Doses of test material above 1.25 µg/plate were toxic to the tester strains. Appropriate positive and solvent controls were included and gave expected results (Dow Corning Corporation, 1985). The results of both studies are in agreement and give evidence that the test substance is non-mutagenic in the bacterial reverse mutation assay under the applied test conditions.

 

The key in vitro cytogenicity study on dichloro(diphenyl)silane was conducted according to OECD TG 473 and to GLP. In the presence and absence of metabolic activation no biologically relevant increase in the frequencies of polyploidy cells was found after treatment with the test item in Chinese Hamster V79 cells as compared to the controls. Appropriate positive and solvent controls were included and gave expected results. The test substance was therefore considered to be non-clastogenic in Chinese Hamster V79 cells (BSL, 2012).

 

No data on in vitro gene mutation in mammalian cells of dichloro(diphenyl)silane is available. However, an OECD 490 study with the registered substance is on-going, but the results will not be available for this current dossier update. Therefore, as an interim measure, the hazard assessment was performed based on available data from the structural analogue trichloro(phenyl)silane (CAS 98-13-5). In accordance with Regulation (EC) No. 1907/2006 Annex XI, 1.5 “Grouping of substances and read across” and in accordance with the Read across assessment framework (RAAF, ECHA 2017) read across from analogue substances has been applied to support the human health hazard assessment of dichloro(diphenyl)silane (CAS 80-10-4). Further details are provided in the analogue justification attached to the respective target entry.

The key in vitro mammalian cell gene mutation study on the structural analogue substance trichlorophenylsilane (CAS 98-13-5) was conducted according to OECD TG 476 and to GLP. No increase in mutant frequency was observed at any concentration with and without metabolic activation after 4 hours of treatment and without metabolic activation after 24 hours of treatment. Expected results were obtained with positive and negative controls. It was concluded that the structural analogue substance, trichlorophenylsilane is negative for the induction of mutations in L5178Y cells under the conditions of the test (Harlan, 2010).

 

In vivo testing is not required as no evidence for genetic toxicity was found in the in vitro studies.

Justification for classification or non-classification

The available in vitro data on mutagenicity of the registered substance and the structural analogue substance, trichloro(phenyl)silane (CAS 98-13-5) do not meet the criteria for classification according to Regulation (EC) No. 1272/2008, and are therefore conclusive but not sufficient for classification.