Trichloro(3,3,4,4,5,5,6,6,7,7,8,8,8-tridecafluorooctyl)silane

Endpoint summary

Key value for chemical safety assessment

Genetic toxicity in vitro

Description of key information

No data are available for the genetic toxicity of [2-(perfluorohexyl)ethyl]trichlorosilane (CAS 78560-45-9, EC 278-947-6), therefore reliable data are read across from bacterial mutagenicity studies with the structural analogues [2-(perfluorohexyl)ethyl]dichloro(methyl)silane (CAS 73609-36-6) and dichloromethyl(3,3,3-trifluoropropyl)silane (CAS 675-62-7), and fromin vitrocytogenicity and mutagenicity studies in mammalian cells with dichloromethyl(3,3,3-trifluoropropyl)silane (CAS 675-62-7).

In vitro:
Gene mutation (Bacterial reverse mutation assay / Ames test): read-across from structural analogue [2-(perfluorohexyl)ethyl]dichloro(methyl)silane (CAS 73609-36-6): negative with and without activation in Salmonella typhimurium strains TA 1535, TA 1537, TA 98, TA 100 and TA 102 (OECD TG 471) (LPT, 2002, reliability 1).

Gene mutation (Bacterial reverse mutation assay / Ames test): read-across from structural analogue dichloromethyl(3,3,3-trifluoropropyl)silane (CAS 675-62-7): negative with and without metabolic activation in S. typhimurium TA 1535, TA 1537, TA 1538, TA 98, and TA 100 (similar to OECD TG 471) (Dow Corning Corporation 1979, reliability 2).

Mammalian cytogenicity (chromosome aberration assay): read across from structural analogue dichloromethyl(3,3,3-trifluoropropyl)silane (CAS 675-62-7): negative with and without metabolic activation in Chinese hamster V79 cells (OECD TG 473) (BSL BIOSERVICE, 2012b, relaibility 1).

Mammalian mutagenicity (Mouse Lymphoma Assay): read across from structural analogue dichloromethyl(3,3,3-trifluoropropyl)silane (CAS 675-62-7): negative with and without metabolic activation (OECD TG 476) (BSL BIOSERVICE, 2012a, reliability 1).

Link to relevant study records

Reference

Reference 1

Endpoint:

in vitro gene mutation study in bacteria

Type of information:

experimental study

Adequacy of study:

weight of evidence

Reliability:

2 (reliable with restrictions)

Rationale for reliability incl. deficiencies:

comparable to guideline study with acceptable restrictions

Remarks:

The restrictions were that the test did not include an additional strain to detect cross-linking mutagens. In view of the lack of genetic toxicity demonstrated in studies on mammalian cells, and the absence of structural features that indicate that such mutagenicity is likely, testing in an appropriate 5th strain is not considered necessary. In addition, the only silicon-containing substance which has given a positive result in a bacterial strain capable of detecting cross-linking or oxidising mutagens contains an epoxy- side-chain (which is associated with cross-linking mutagenicity), and this substance was positive in Salmonella typhimurium strains TA 100, TA 1535 as well as in E.coli WP2uvrA

Qualifier:

equivalent or similar to guideline

Guideline:

OECD Guideline 471 (Bacterial Reverse Mutation Assay)

Version / remarks:

(adopted 1997)

Deviations:

yes

Remarks:

(the test did not include an additional strain to detect cross-linking mutagens; only 4 concentrations instead of 5 stated in the guideline were tested)

GLP compliance:

no

Type of assay:

bacterial reverse mutation assay

Target gene:

his-operon

Species / strain / cell type:

S. typhimurium TA 1538

Species / strain / cell type:

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

Metabolic activation:

with and without

Metabolic activation system:

Aroclor 1254 induced rat liver

Test concentrations with justification for top dose:

0.5, 5, 100, or 500 μl/plate

Vehicle / solvent:

The solvent (negative control) for all treatment/strains was deionised water, absolute ethanol or dimethylsulfoxide (DMSO).

Untreated negative controls:

no

Negative solvent / vehicle controls:

yes

True negative controls:

no

Positive controls:

yes

Positive control substance:

other: -S9: TA100 and TA1535 (Sodium azide 100 µg/plate), TA1537 (9-Aminoacridine 100 µg/plate) and TA 1538 (2-Nitrofluorene 100 µg/plate).

Untreated negative controls:

no

Negative solvent / vehicle controls:

yes

True negative controls:

no

Positive controls:

yes

Positive control substance:

other: 2-Anthramine (Anth) +S9: All strains = 100 µg/plate. -S9: TA 98 and TA1538 =100 µg/plate.

Details on test system and experimental conditions:

METHOD OF APPLICATION: in agar (plate incorporation)

DURATION
- Exposure duration: 48 hours

NUMBER OF REPLICATIONS: 3

Evaluation criteria:

Strains TA 1535, TA 1537 and TA 1538:
If the solvent control value is within the normal range, a chemical that produces a positive dose response over three concentrations with the lowest increase equal to twice the solvent control value is considered to be mutagenic.
Strains TA 98 and TA 100:
If the solvent control value is within the normal range, a chemical that produces a positive dose response over three concentrations with the highest increase equal to twice the solvent control for TA 100 and two to three times solvent control value for strain TA 98 is considered to be mutagenic. For these strains, the dose response increase should start at approximately the solvent control values.
Reproducibility: If a chemical produces a response in a single test that cannot be reproduced in one or more additional runs, the initial positive test data loses significance.

Statistics:

Not reported

Key result

Species / strain:

S. typhimurium TA 98

Metabolic activation:

with and without

Genotoxicity:

negative

Cytotoxicity / choice of top concentrations:

not specified

Vehicle controls validity:

valid

Untreated negative controls validity:

not applicable

Positive controls validity:

valid

Key result

Species / strain:

S. typhimurium TA 100

Metabolic activation:

with and without

Genotoxicity:

negative

Cytotoxicity / choice of top concentrations:

not specified

Vehicle controls validity:

valid

Untreated negative controls validity:

not applicable

Positive controls validity:

valid

Key result

Species / strain:

S. typhimurium TA 1535

Metabolic activation:

with and without

Genotoxicity:

negative

Cytotoxicity / choice of top concentrations:

not specified

Vehicle controls validity:

valid

Untreated negative controls validity:

not applicable

Positive controls validity:

valid

Key result

Species / strain:

S. typhimurium TA 1537

Metabolic activation:

with and without

Genotoxicity:

negative

Cytotoxicity / choice of top concentrations:

not specified

Vehicle controls validity:

valid

Untreated negative controls validity:

not applicable

Positive controls validity:

valid

Key result

Species / strain:

S. typhimurium TA 1538

Metabolic activation:

with and without

Genotoxicity:

negative

Cytotoxicity / choice of top concentrations:

not specified

Vehicle controls validity:

valid

Untreated negative controls validity:

not applicable

Positive controls validity:

valid

Additional information on results:

Not reported

Table 1: Overlay plate test results

Test	Revertants per plate
	TA 1535	TA 1537	TA 1538	TA 98	TA 100
Non-activation
Solvent control	23	5	38	20	176
Postive control*	173	61	294	154	>10^3
Test material (µl)
0.5	22	3	40	23	142
5	21	6	38	20	160
100	28	4	40	21	164
500	20	4	32	22	114
Activation
Solvent control	24	7	36	26	181
Postive control**	263	97	>10^3	>10^3	>10^3
Test material (µl)
0.5	22	6	45	26	191
5	26	4	39	26	197
100	23	4	41	29	183
500	22	3	30	24	156
* TA-1535	AZ 100 µg/plate		** TA-1535	ANTH 100 µg/plate
*TA-1537	AZ 100 µg/plate		**TA-1537	ANTH 100 µg/plate
*TA-1538	NF 100 µg/plate		**TA-1538	ANTH 100 µg/plate
*TA98	NF 100 µg/plate		**TA98	ANTH 100 µg/plate
*TA100	AZ 100 µg/plate		**TA100	ANTH 100 µg/plate
Solvent	DMSO 50 µl/plate		Solvent	DMSO 50 µl/plate

Conclusions:

Dichloromethyl(3,3,3-trifluoropropyl)silane has been tested for bacterial mutagenicity (Ames Test) in a study conducted according to a protocol similar to the OECD TG 471 which predates GLP. The Salmonella typhimurium strains TA 1535, TA 1537, TA 1538, TA 98, and TA 100 were exposed to the test material both in absence and presence of a metabolic activation system. An additional strain for the detection of cross-linking agents was not included into the test. No treatment related increase in the number of revertants was observed in any of the tester strains. Appropriate solvent and positive controls were included into the test and gave the expected results. Hence, the test item was considered to be non-mutagenic to bacteria under the conditions of the test.

Reference 2

Endpoint:

in vitro gene mutation study in bacteria

Type of information:

experimental study

Adequacy of study:

weight of evidence

Study period:

2002-05-03 to 2002-08-01

Reliability:

1 (reliable without restriction)

Rationale for reliability incl. deficiencies:

guideline study

Qualifier:

according to guideline

Guideline:

OECD Guideline 471 (Bacterial Reverse Mutation Assay)

Deviations:

no

GLP compliance:

yes (incl. QA statement)

Type of assay:

bacterial reverse mutation assay

Target gene:

histidine operon

Species / strain / cell type:

S. typhimurium TA 1535, TA 1537, TA 98, TA 100 and TA 102

Metabolic activation:

with and without

Metabolic activation system:

Aroclor induced rat liver S9

Test concentrations with justification for top dose:

10, 31.6, 100, 316, 1000 µg/plate

Vehicle / solvent:

- Vehicle(s)/solvent(s) used: Ethylene glycol dimethylether

- Justification for choice of solvent/vehicle: Solubility properties and relative non-toxicity to bacteria

Untreated negative controls:

no

Negative solvent / vehicle controls:

yes

True negative controls:

no

Positive controls:

yes

Positive control substance:

sodium azide

Remarks:

TA 1535, TA 100 (without activation)

Untreated negative controls:

no

Negative solvent / vehicle controls:

yes

True negative controls:

no

Positive controls:

yes

Positive control substance:

2-nitrofluorene

Remarks:

TA 98 (without activation)

Untreated negative controls:

no

Negative solvent / vehicle controls:

yes

True negative controls:

no

Positive controls:

yes

Positive control substance:

9-aminoacridine

Remarks:

TA 1537 (without activation)

Untreated negative controls:

no

Negative solvent / vehicle controls:

yes

True negative controls:

no

Positive controls:

yes

Positive control substance:

methylmethanesulfonate

Remarks:

TA 102 (without activation)

Untreated negative controls:

no

Negative solvent / vehicle controls:

yes

True negative controls:

no

Positive controls:

yes

Positive control substance:

other: 2-anthracene amide

Remarks:

TA 98, TA 102, TA 1537 (with activation)

Untreated negative controls:

no

Negative solvent / vehicle controls:

yes

True negative controls:

no

Positive controls:

yes

Positive control substance:

cyclophosphamide

Remarks:

TA 100, TA 1535 (with activation)

Details on test system and experimental conditions:

METHOD OF APPLICATION: in medium (plate incorporation); preincubation

DURATION

- Preincubation period: 60 minutes

- Expression time (cells in growth medium): 48 hours

NUMBER OF REPLICATIONS: 3 plates for each test concentration; the initial plate incorporation assay was repeated using the pre-incubation method.

DETERMINATION OF CYTOTOXICITY

- Method: Background lawn assessment, relative colony counts

METABOLIC ACTIVATION
Aroclor induced rat liver S9 was tested for protein and P-450 content. S9 mix contained 5% S9, and glucose-6-phosphate and NADP as co-factors. 0.5 ml S9 mix were added to 2 ml top agar, 0.1 ml test material and 0.1 ml cell suspension, giving a final concentration of approximately 1% S9.

Evaluation criteria:

A result is positive if the number of revertants is significantly increased compared with the solvent control to at least 2-fold of the solvent control for TA 98, TA 100 and TA 102 and 3-fold of the solvent control for TA 1535 and TA 1537 in both experiments.

Positive results have to be reproducible and the histidine independence of the revertants has to be confirmed by streaking on histidine-free agar plates.

Cytotoxicity is defined as a reduction in the number of colonies by >50% compared with the solvent control and/or a sparse background lawn.

Statistics:

MANN and WHITNEY and Spearman’s rank.

Key result

Species / strain:

S. typhimurium TA 98

Metabolic activation:

without

Genotoxicity:

negative

Cytotoxicity / choice of top concentrations:

cytotoxicity

Remarks:

316 - 1000 μg/plate

Vehicle controls validity:

valid

Untreated negative controls validity:

not applicable

Positive controls validity:

valid

Key result

Species / strain:

S. typhimurium TA 98

Metabolic activation:

with

Genotoxicity:

negative

Cytotoxicity / choice of top concentrations:

cytotoxicity

Remarks:

1000 μg/plate

Vehicle controls validity:

valid

Untreated negative controls validity:

not applicable

Positive controls validity:

valid

Key result

Species / strain:

S. typhimurium TA 100

Metabolic activation:

with and without

Genotoxicity:

negative

Cytotoxicity / choice of top concentrations:

cytotoxicity

Remarks:

1000 μg/plate

Vehicle controls validity:

valid

Untreated negative controls validity:

not applicable

Positive controls validity:

valid

Key result

Species / strain:

S. typhimurium TA 102

Metabolic activation:

with and without

Genotoxicity:

negative

Cytotoxicity / choice of top concentrations:

cytotoxicity

Remarks:

316 - 1000 μg/plate

Vehicle controls validity:

valid

Untreated negative controls validity:

not applicable

Positive controls validity:

valid

Key result

Species / strain:

S. typhimurium TA 1535

Metabolic activation:

without

Genotoxicity:

negative

Cytotoxicity / choice of top concentrations:

cytotoxicity

Remarks:

316 - 1000 μg/plate

Vehicle controls validity:

valid

Untreated negative controls validity:

not applicable

Positive controls validity:

valid

Key result

Species / strain:

S. typhimurium TA 1535

Metabolic activation:

with

Genotoxicity:

negative

Cytotoxicity / choice of top concentrations:

cytotoxicity

Remarks:

1000 μg/plate

Vehicle controls validity:

valid

Untreated negative controls validity:

not applicable

Positive controls validity:

valid

Key result

Species / strain:

S. typhimurium TA 1537

Metabolic activation:

with and without

Genotoxicity:

negative

Cytotoxicity / choice of top concentrations:

cytotoxicity

Remarks:

316 - 1000 μg/plate

Vehicle controls validity:

valid

Untreated negative controls validity:

not applicable

Positive controls validity:

valid

Additional information on results:

COMPARISON WITH HISTORICAL CONTROL DATA: Results were within range of historical control data

Table 2: Dose range-finding study Number of revertants per plate (mean of 2 plates)

	TA100
Conc. (µg/plate)	Plate 1	Plate 2	Cytotoxic (yes/no)
0*	112	115	No
0.316	117	105	No
1	111	110	No
3.16	126	112	No
10	101	114	No
31.6	116	121	No
100	172	181	No
316	165	173	No
1000	132	154	Yes
3160	0	0	Yes
5000	0	0	Yes

*solvent control with Ethylene glycol dimethylether

Table 3a: Experiment 1 Plate incorporation Number of revertants per plate (mean of 3 plates)

	TA98			TA100			TA102
Conc. (µg/plate)	— MA	+ MA	Cytotoxic (yes/no)	—  MA	+ MA	Cytotoxic (yes/no)	— MA	+  MA	Cytotoxic (yes/no)
0*	42	51.7	No	133	158	No	278	295	No
10	36.3	48.7	No	154	148	No	274.7	273.7	No
31.6	34.7	53	No	139	153.3	No	268.3	275	No
100	34.3	57	No	137.7	131.3	No	271.3	270	No
316	47.7	47.3	No	143.3	139.3	No	258	272.3	No
1000	31.3	40.3	Yes	131	160.7	Yes	286.7	267.3	Yes
Positive control	1145.7	1100	No	1194.3	1196.3	No	1320	1150.3	No

*solvent control with Ethylene glycol dimethylether

Table 3b: Experiment 1 Plate incorporation Number of revertants per plate (mean of 3 plates)

	TA1535			TA1537
Conc.µg/plate	— MA	+  MA	Cytotoxic (yes/no)	— MA	+  MA	Cytotoxic (yes/no)
0*	13	15.3	No	6	4	No
10	13	12	No	3.7	4.7	No
31.6	14.7	14	No	3.3	5.7	No
100	14.3	13	No	3	2.7	No
316	11	13	No	3.7	4.7	No
1000	12	16.3	No	4.3	3.3	No
Positive control	1187	1189	No	1191.3	1241.7	No

*solvent control with Ethylene glycol dimethylether

Table 4a: Experiment 2 Preincubation Number of revertants per plate (mean of 3 plates)

	TA98			TA100			TA102
Conc. µg/plate	— MA	+  MA	Cytotoxic (yes/no)	— MA	+  MA	Cytotoxic (yes/no)	—  MA	+  MA	Cytotoxic (yes/no)
0*	37.3	30.7	No	143.7	154	No	280.3	290.3	No
10	31.7	30.3	No	187	160.7	No	276.3	283.7	No
31.6	38	35.7	No	171.7	144.7	No	288.7	286.3	No
100	35	36.3	No	178	152	No	283.3	281.7	No
316	0	36	Yes	162.7	144.7	No	297.3	265	Yes
1000	0	0	Yes	0	0	Yes	0	0	Yes
Positive control	894.3	983.7	No	1326.3	1333.3	No	1338.3	1344.3	No

*solvent control with Ethylene glycol dimethylether

Table 4b: Experiment 2 Preincubation Number of revertants per plate (mean of 3 plates)

	TA1535			TA1537
Conc. µg/plate	— MA	+ MA	Cytotoxic (yes/no)	— MA	+  MA	Cytotoxic (yes/no)
0*	13.7	13	No	3	4.3	No
10	13.3	13.7	No	3	4.7	No
31.6	14.3	12	No	3	3.3	No
100	12.3	12.3	No	2.3	4.3	No
316	14.3	12	Yes	4	4.3	Yes
1000	0	12.7	Yes	0	0	Yes
Positive control	487.3	499.7	No	502	503	No

*solvent control with Ethylene glycol dimethylether

Conclusions:

[2-(Perfluorohexyl)ethyl]dichloro(methyl)silane has been tested in a reliable study, conducted according to OECD 471 and in compliance with GLP. No test-substance related increase in the number of revertants was observed with and without metabolic activation when tested up to cytotoxic concentration in Salmonella typhimurium strains TA 1535, TA 1537, TA 98, TA 100 and TA 102. The result of the initial plate incorporation assay was confirmed in an independent experiment using the pre-incubation method. Appropriate positive and solvent controls were included and gave expected results. It is concluded that the substance is negative for mutagenicity to bacteria under the conditions of the test.

Reference 3

Endpoint:

in vitro cytogenicity / chromosome aberration study in mammalian cells

Type of information:

experimental study

Adequacy of study:

key study

Study period:

03 August 2011 to 20 December 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)

Version / remarks:

(1997)

Deviations:

no

Qualifier:

according to guideline

Guideline:

EPA OPPTS 870.5375 - In vitro Mammalian Chromosome Aberration Test

Version / remarks:

(1998)

Deviations:

no

Qualifier:

according to guideline

Guideline:

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

Version / remarks:

(2008)

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:

Liver S9 of Wistar phenobarbital and ß-naphthoflavone-induced rat liver S9 mix

Test concentrations with justification for top dose:

Pre-experiment:
with and without metabolic activation: 0.020, 0.039, 0.078, 0.16, 0.31, 0.63, 1.25, 2.5, 5.0, and 10.0 mM

Experiment I:
without metabolic activation: 0.63, 1.25, and 2.5 mM
with metabolic activation: 1.25, 2.5, and 5.0 mM
Experiment II:
without metabolic activation: 0.16, 0.63, and 1.75 mM
with metabolic activation: 2.0, 4.0, and 6.0 mM

Vehicle / solvent:

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

Untreated negative controls:

yes

Negative solvent / vehicle controls:

yes

True negative controls:

no

Positive controls:

yes

Positive control substance:

ethylmethanesulphonate

Remarks:

without metabolic activation: 400 and 900 µg/ml

Untreated negative controls:

yes

Negative solvent / vehicle controls:

yes

True negative controls:

no

Positive controls:

yes

Positive control substance:

cyclophosphamide

Remarks:

with metabolic activation: 0.83 µg/ml

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: 1E4 - 5E4 cells
NUMBER OF CULTURES: two cultures per concentration
NUMBER OF CELLS SCORED: 200 cells per concentration (100 cells per culture), (except in experiment I at a concentration of 0.63 mM without metabolic activation: 250 cells and in experiment II at a concentration of 2 mM with metabolic activation: 300 cells).
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.

Key result

Species / strain:

Chinese hamster lung fibroblasts (V79)

Metabolic activation:

with and without

Genotoxicity:

negative

Cytotoxicity / choice of top concentrations:

cytotoxicity

Vehicle controls validity:

valid

Untreated negative controls validity:

valid

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
solvent control	200	-	2	1	0	0	0	0	0	0	100	100	1	1.5	0.5
0.16 mM	-	no	n.d.	n.d.	n.d.	n.d.	n.d.	n.d.	n.d.	n.d.	83	n.d.	n.d.	n.d.	n.d.
0.31 mM	-	no	n.d.	n.d.	n.d.	n.d.	n.d.	n.d.	n.d.	n.d.	98	n.d.	n.d.	n.d.	n.d.
0.63 mM	250	no	5	4	1	0	0	0	2	0	93	93	3	4.8	2.8
1.25 mM	200	no	3	1	0	0	0	0	0	0	82	97	2	2.0	0.5
2.5 mM	200	yes	7	3	0	0	1	0	0	0	40	71	0	4.0	1.5
5.0 mM	-	yes	n.d.	n.d.	n.d.	n.d.	n.d.	n.d.	n.d.	n.d.	18	n.d.	n.d.	n.d.	n.d.
EMS 900 µg/mL	200	-	5	13	8	1	0	0	0	3	61	74	1	12.5	11.5
Experiment II
solvent control	200	-	1	0	0	0	0	0	2	0	100	100	0	1.5	1.0
0.08 mM	-	no	n.d.	n.d.	n.d.	n.d.	n.d.	n.d.	n.d.	n.d.	80	n.d.	n.d.	n.d.	n.d.
0.16 mM	200	no	3	0	0	0	1	0	0	0	85	92	2	2.0	0.0
0.31 mM	200	yes	n.d.	n.d.	n.d.	n.d.	n.d.	n.d.	n.d.	n.d.	56	n.d.	n.d.	n.d.	n.d.
0.63 mM	200	yes	0	0	0	0	0	0	0	0	54	77	1	0.0	0.0
1.25 mM	-	yes	n.d.	n.d.	n.d.	n.d.	n.d.	n.d.	n.d.	n.d.	46	n.d.	n.d.	n.d.	n.d.
1.75 mM	200	yes	5	2	1	1	0	0	1	0	48	56	0	4.5	2.5
2.5 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.
5.0 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.
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
solvent control	200	-	8	5	0	0	0	0	0	0	100	100	2	5.5	2.5
0.63 mM	-	no	n.d.	n.d.	n.d.	n.d.	n.d.	n.d.	n.d.	n.d.	98	n.d.	n.d.	n.d.	n.d.
1.25 mM	200	no	4	1	0	0	0	0	0	0	77	72	2	2.5	0.5
2.5 mM	200	yes	1	1	0	1	0	0	0	0	62	93	0	1.5	1.0
5.0 mM	200	yes	3	1	0	0	0	0	0	0	40	76	2	2.0	0.5
7.5 mM	-	yes	n.d.	n.d.	n.d.	n.d.	n.d.	n.d.	n.d.	n.d.	14	n.d.	n.d.	n.d.	n.d.
10.0 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	-	3	9	6	1	1	1	0	1	74	81	1	10.0	8.5
Experiment II
solvent control	200	-	2	1	2	1	0	0	0	0	100	100	2	2.5	1.5
0.5 mM	-	no	n.d.	n.d.	n.d.	n.d.	n.d.	n.d.	n.d.	n.d.	103	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.	80	n.d.	n.d.	n.d.	n.d.
2.0 mM	300	no	3	6	0	1	0	0	2	0	87	98	2.5	3.7	3.0
4.0 mM	200	no	3	2	0	1	1	0	2	0	87	99	3	4.0	2.5
6.0 mM	200	yes	7	3	0	1	1	0	1	0	46	80	2	6.5	2.5
8.0 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.
10.0 mM	-	yes	n.d.	n.d.	n.d.	n.d.	n.d.	n.d.	n.d.	n.d.	3	n.d.	n.d.	n.d.	n.d.
CPA 0.83 µg/mL	200	-	0	10	5	1	1	0	0	2	88	98	1	9.0	8.5

n.d. not determined

Conclusions:

Dichloromethyl(3,3,3-trifluoropropyl)silane was tested for in vitro cytogenicity to mammalian cells according to the OECD TG 473 and in compliance with GLP. The test item did not induce structural chromosomal aberrations in the V79 Chinese hamster cell line with and without metabolic activation up to cytotoxic concentrations. Appropriate positive and solvent controls were included into the study and gave the expected results. The test item is therefore considered to be non-clastogenic under the conditions of the test.

Reference 4

Endpoint:

in vitro gene mutation study in mammalian cells

Type of information:

experimental study

Adequacy of study:

key study

Study period:

08 Aug - 24 Nov 2011

Reliability:

1 (reliable without restriction)

Rationale for reliability incl. deficiencies:

guideline study

Qualifier:

according to guideline

Guideline:

OECD Guideline 476 (In Vitro Mammalian Cell Gene Mutation Test)

Version / remarks:

1997

Deviations:

no

Qualifier:

according to guideline

Guideline:

EU Method B.17 (Mutagenicity - In Vitro Mammalian Cell Gene Mutation Test)

Deviations:

no

Qualifier:

according to guideline

Guideline:

EPA OPPTS 870.5300 - In vitro Mammalian Cell Gene Mutation Test

Deviations:

no

Qualifier:

according to guideline

Guideline:

other: IWGT Recommendations

Deviations:

no

GLP compliance:

yes (incl. QA statement)

Remarks:

(Bayerisches Landesamt für Gesundheit und Lebensmittelsicherheit, Landesinstitut für Arbeitsschutz und Produktsicherheit, Munich, Germany)

Type of assay:

mammalian cell gene mutation assay

Target gene:

Thymidine kinase gene

Species / strain / cell type:

mouse lymphoma L5178Y cells

Details on mammalian cell type (if applicable):

- Type and identity of media: RPMI 1640 supplemented with: 10 % horse serum (HS), 100 U/100 µg/mL penicillin/streptomycin, 1 mM sodium pyruvate, 2 mM L-glutamine, 25 mM HEPES, 2.5 µg/mL amphotericin B
- Properly maintained: Yes
- Periodically checked for Mycoplasma contamination: yes
- Periodically "cleansed" against high spontaneous background: yes

Metabolic activation:

with and without

Metabolic activation system:

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

Test concentrations with justification for top dose:

Pre-experiment I with metabolic activation: 0.1, 0.5, 2.5, 5.0, and 7.5 mM
Pre-experiment I without metabolic activation: 0.1, 0.5, 2.5, and 5.0 mM

Pre-experiment II without metabolic activation (24 h long-term exposure): 0.05, 0.1, 0,5, 1.0, 2.0, and 4.0 mM

Experiment I
with metabolic activation: (4 hours)
0.2, 0.5, 1.0, 2.0, 3.0, 4.0, 4.5, and 5.0 mM
and without metabolic activation: (4 hours)
0.05, 0.1, 0.2, 0.5, 1.0, 1.5, 2.4, and 2.8 mM

Experiment II
with metabolic activation: (4 hours)
0.7, 1.5, 2.5, 3.4, 4.2, 4.6, 5.2, and 5.6 mM
and without metabolic activation: (24 hours)
0.05, 0.1, 0.2, 0.4, 0.6, 0.7, 0.8, and 1.0 mM

Vehicle / solvent:

RPMI cell culture medium was used as solvent (RPMI + 5% HS).
- Justification for choice of solvent/vehicle: A solubility test was performed using different solvents and vehicles up to the maximum recommended concentration of 10 mM. Based on the results RPMI cell culture medium was chosen as solvent. The pH value was adjusted to physiological pH 7 with 1 M NaOH if necessary. RPMI medium is compatible with survival of the cells and activity of the S9 mix.

Untreated negative controls:

yes

Negative solvent / vehicle controls:

yes

True negative controls:

no

Positive controls:

yes

Positive control substance:

other: Ethylmethanesulfonate (EMS, 200 and 300 µg/ml, -S9); Methylmethanesulfonate (MMS, 10 µg/ml, -S9); Benzo[a]pyrene (B[a]P, 2.5 µg/ml, +S9)

Details on test system and experimental conditions:

METHOD OF APPLICATION: dissolved in medium
DURATION: 4 h (short-term exposure), 24 h (long-term exposure)
Expression time (cells in growth medium): 48 h
Selection time (if incubation with selection agent): about 14 days

SELECTION AGENT ( mutation assay) 5 µg/mL trifluorothymidine
NUMBER OF REPLICATIONS: two separate experiments (I+II) with single exposure; cells were seeded in 4 plates and evaluated
NUMBER OF CELLS SEEDED: 2000 cells per well

DETERMINATION OF CYTOTOXICITY: relative total growth (RTG), cloning efficiency

Evaluation criteria:

The test item is considered mutagenic if following criteria are met:
-The induced mutant frequency meets or exceeds the Global Evaluation factor (GEF) of 126 per 1E+6 cells
- A dose-dependent increase in mutant frequency is detected.

Besides, combined with a positive effect in the mutant frequency, an increased occurrence of small colonies (≥40% of total colonies) is an indication for potential clastogenic effects and/or chromosomal aberrations.
According to the OECD guideline, the biological relevance is considered first for the interpretation of results. Statistical methods might be used as an aid in evaluation the test result.
A test item is considered to be negative if the induced mutant frequency is below the GEF and the trend test is negative.

Statistics:

The non-parametric Mann-Whitney test is applied to the mutation data to prove the dose groups for any significant difference in mutant frequency compared to the negative /solvent controls.

Key result

Species / strain:

mouse lymphoma L5178Y cells

Metabolic activation:

with and without

Genotoxicity:

negative

Cytotoxicity / choice of top concentrations:

cytotoxicity

Vehicle controls validity:

valid

Untreated negative controls validity:

not applicable

Positive controls validity:

valid

Additional information on results:

RANGE-FINDING/SCREENING STUDIES:
Toxicity and precipitation were seen in the pre-experiments I with and without metabolic activation. Toxicity was seen by reduced relative suspension growth (RSG) at 2.5 mM and higher with and without metabolic activation. Precipitation was noted at 5.0 mM without metabolic activation and 7.5 mM with metabolic activation. In pre-experiment II (24 hours), toxicity was seen starting at 0.5 mM and no precipitation was observed.

Table 1: Main Experiment I - Data with metabolic activation

Concentration [mM]	Cloning efficiency [%]	relative total growth [%]	Mutant frequency [mutants/1E+06 cells]	Induced mutant frequency # [mutants/1E+06 cells]	% small colonies
0 (control1)	100.0	100.0	97.0	-	16.7
0 (control2)	100.0	100.0	114.1	-	21.3
0.2	111.4	121.3	100.8	-4.8	-
0.5	100.7	95.8	121.8	16.2	-
1.0	104.3	93.9	129.1	23.5	-
2.0	98.6	84.8	119.3	13.7	-
3.0	105.7	53.0	99.1	-6.5	-
4.0	102.9	24.7	178.3	72.7*	34.3
4.5	113.6	18.1	186.7	81.1*	36.4
5.0	110.0	11.8	193.0	87.4*	31.7
B[a]P (2.5 µg/ml)	90.0	57.6	949.9	844.3*	46.2

Table 2: Main Experiment I - Data without metabolic activation

Concentration [mM]	Cloning efficiency [%]	relative total growth [%]	Mutant frequency [mutants/1E+06 cells]	Induced mutant frequency # [mutants/1E+06 cells]	% small colonies
0 (control1)	100.0	100.0	139.5	-	17.3
0 (control2)	100.0	100.0	89.4	-	22.2
0.05	104.2	110.4	116.6	2.2	15.4
0.1	102.8	101.8	98.9	-15.5	-
0.2	106.3	101.5	102.7	-11.7	-
0.5	93.0	84.4	111.1	-3.4	-
1.0	100.0	78.6	114.4	-0.1	-
1.5	98.6	39.8	112.2	-2.3	15.4
2.4	106.3	19.7	129.8	15.3	31.4
2.8	100.0	6.9	140.8	26.4	40.0
EMS (300 µg/ml)	90.9	75.1	926.8	812 .3*	-
MMS (10 µg/ml)	85.3	62.9	872.1	757.7*	59.2

Table 3: Main Experiment II - Data with metabolic activation

Concentration [mM]	Cloning efficiency [%]	relative total growth [%]	Mutant frequency [mutants/1E+06 cells]	Induced mutant frequency # [mutants/1E +06 cells]	% small colonies
0 (control1)	100.0	100.0	80.9	-	26.4
0 (conrol2)	100.0	100.0	77.7	-	21.8
0.7	91.0	81.6	103.2	23.9	-
1.5	95.0	87.0	90.7	11.4	-
2.5	95.7	70.5	72.4	-6.9	-
3.4	92.4	49.8	117.5	38.2*	-
4.2	91.7	33.7	103.4	24.1*	-
4.6	99.7	32.2	112.9	33.6*	29.7
5.2	99.0	21.1	91.6	12.3	35.0
5.6	88.4	8.6	104.8	25.5*	29.1
B[a]P (2.5 µg/ml)	88.4	57.8	630.1	550.8*	47.2

Table 4: Main Experiment II - Data without metabolic activation

Concentration [mM]	Cloning Efficiency [%]	relative total growth [%]	Mutant frequency [mutants/1E+06 cells]	Induced mutant frequency # [mutants/1E+06 cells]	% small colonies
0 (control1)	100.0	100.0	83.1	-	6.0
0 (control2)	100.0	100.0	98.2	-	15.9
0.05	95.2	82.7	94.7	4.1	-
0.1	104.1	78.7	69.5	-21.2	-
0.2	95.2	66.3	56.8	-33.9*	-
0.4	82.1	58.3	139.0	48.3	-
0.6	100.7	46.2	95.3	4.6
0.7	96.6	26.2	112.0	21.3	10.9
0.8	97.9	24.7	101.0	10.3	15.0
1.0	100.0	9.8	86.2	-4.4	20.4
EMS (200 µg/ml)	46.9	20.9	3689.7	3599.0*	-
MMS (10 µg/ml)	46.9	19.5	1889.6	1798.9*	44.1

* Significantly different to solvent control, p<0.05

# Induced mutant frequency = mutant frequency sample - mean value mutant frequency corresponding controls

Conclusions:

Dichloromethyl(3,3,3-trifluoropropyl)silane has been tested for mutagenicity to mammalian cells in a study conducted according to OECD 476 and GLP. No increase in mutant frequency was observed in the presence or absence of metabolic activation. It is concluded that, under the experimental conditions reported, the test substance is non-mutagenic in the in vitro mammalian cell gene mutation assay (thymidine kinase locus) in mouse lymphoma L5178Y cells.

Endpoint conclusion

Endpoint conclusion:

no adverse effect observed (negative)

Genetic toxicity in vivo

Endpoint conclusion

Endpoint conclusion:

no study available

Additional information

No data are available for the genetic toxicity of [2-(perfluorohexyl)ethyl]trichlorosilane (CAS 78560-45-9, EC 278-947-6), therefore reliable data are read across from bacterial mutagenicity studies with the structural analogues [2-(perfluorohexyl)ethyl]dichloro(methyl)silane (CAS 73609-36-6) and dichloromethyl(3,3,3-trifluoropropyl)silane (CAS 675-62-7), and from in vitro cytogenicity and mutagenicity studies in mammalian cells with dichloromethyl(3,3,3-trifluoropropyl)silane (CAS 675-62-7). The results of all the studies are negative.

Non-testing methods including read-across from surrogate substances are able to provide information on genetic toxicity (REACH Guidance part 07a, R.7.7.3). In the case of genetic toxicity the presence or absence of functional groups that are known to be related to genetic toxicity is considered important, as the presence or absence of reactive groups and molecular substructures is associated with mutagenic and carcinogenic properties of chemicals (Benigni and Bossa, 2006). Consideration is therefore given to the structural similarity, particularly presence or absence of structural alerts for genetic toxicity, when selecting surrogate substances for genetic toxicity endpoints. Additional information is given in a supporting report (PFA 2013aa) attached in Section 13.

Read-across justification

There are no available measured data for trichloro(3,3,4,4,5,5,6,6,7,7,8,8,8-tridecafluorooctyl)silane (CAS 78560-45-9) for in vitro genetic toxicity. Therefore, the Annex requirements are fulfilled with data on two structurally analogous substances. This document describes the analogue approach for fulfilling bacterial mutagenicity endpoint by read-across from the source substances, [2-(perfluorohexyl)ethyl]dichloro(methyl)silane (CAS 73609-36-6) and dichloromethyl(3,3,3-trifluoropropyl)silane (CAS 675-62-7), and mammalian cytogenicity and mutagenicity by read-across from dichloromethyl(3,3,3-trifluoropropyl)silane (CAS 675-62-7 according to the Read-across Assessment Framework (RAAF) .

Read-across is proposed in accordance with RAAF Scenario 2: “This scenario covers the analogue approach for which the read-across hypothesis is based on different compounds which have the same type of effect(s). For the REACH information requirement under consideration, the effects obtained in a study conducted with one source substance are used to predict the effects that would be observed in a study with the target substance if it were to be conducted. The same type of effect(s) or absence of effect is predicted. The predicted strength of the effects may be similar or based on a worst case.”

The read-across justification is presented (Table 1) according to RAAF scenario 2 assessment elements (AE) as outlined in Table B1 of the RAAF1:

Table 1: RAAF scenario 2 assessment elements (AE) as given in Appendix B (Table B1) of the RAAF

AE A.1	Characterisation of source substance
AE A.2	Link of structural similarity and differences with the proposed Prediction
AE A.3	Reliability and adequacy of the source study
AE 2.1	Compounds the test organism is exposed to
AE 2.2	Common underlying mechanism, qualitative aspects
AE 2.3	Common underlying mechanism, quantitative aspects
AE 2.4	Exposure to other compounds than to those linked to the prediction
AE 2.5	Occurrence of other effects than covered by the hypothesis and Justification
AE A.4	Bias that influences the prediction

1. AE A.1 Identity and characterisation of the source substance

The first source substance, [2-(perfluorohexyl)ethyl]dichloro(methyl)silane (CAS 73609-36-6), belongs to an analogue group of organosilicon substances with highly (but no fully) fluorinated side chains. Apart from being attached to a highly fluorinated side chain, the silicon atom is also attached to a methyl group and two chlorine groups. The substance hydrolyses rapidly in contact with water and the hydrolysis products are hydrogen chloride and [2‑(perfluorohexyl)ethyl]methylsilanediol.  The predicted half-lives of hydrolysis are approximately 5 seconds as a worst case at 25°C and pH 4, 7 and 9 (analogue read-across).

The values for logKow and water solubility for the source substance are not relevant as the substance is hydrolyses rapidly in water. The vapour pressure of the source substance is 0.04 Pa at 20°C, 30 Pa at 50°C (EU Method A.4).

The second source substance, dichloromethyl(3,3,3-trifluoropropyl)silane (CAS 675-62-7), belongs to the same analogue group and has a shorter highly (but not fully) fluorinated side chain and two chlorine and one methyl groups attached to the silicon. It also hydrolyses rapidly to give hydrogen chloride and methyl(3,3,3-trifluoropropyl)silanediol. Half-life estimates are < 17 seconds for pH 4, 7, and 9 at 1.5°C.

The values for logKow and water solubility for the source substance are not relevant as the substance is hydrolyses rapidly in water. The vapour pressure of the source substance is 740 Pa at 25°C  (QSAR).

2. AE A.2 Link of structural similarities and differences with the proposed prediction

The registration and read-across substances belong to an analogue group of organosilicon substances with highly (but no fully) fluorinated side chains. The substances hydrolyse very rapidly to produce the corresponding Si-hydrolysis products and hydrochloric acid. The reaction is typically so rapid that its precise half-life is not significant (in some cases, it is so fast that it cannot be quantified). As the hydrolysis reaction may be acid or base-catalysed, the rate of reaction is expected to be slowest at around pH 7 and increase as the pH is raised or lowered.

The registration substance, trichloro(3,3,4,4,5,5,6,6,7,7,8,8,8-tridecafluorooctyl)silane (CAS 78560-45-9) hydrolyses very rapidly, with a hydrolysis half-life of approximately 5 seconds at 25°C and pH 4, 7 and 9. At physiologically relevant conditions, the rate of hydrolysis would be faster, therefore a hydrolysis half-life at pH 7 and 37.5 °C has been estimated  to be < 5 seconds. The products of hydrolysis are hydrochloric acid and [2-(perfluorohexyl)ethyl]silanetriol.

The source substances [2-(perfluorohexyl)ethyl]dichloro(methyl)silane (CAS 73609-36-6) and  dichloromethyl(3,3,3-trifluoropropyl)silane (CAS 675-62-7) hydrolyse very rapidly to produce [2‑(perfluorohexyl)ethyl]methylsilanediol, methyl(3,3,3-trifluoropropyl)silanediol and hydrochloric acid. None of the substances or hydrolysis products has structural alerts for genotoxicity (Benigni et al., 2008). The reaction is typically so rapid that its precise half-life is not significant (in some cases, it is so fast that it cannot be quantified). The source substances estimated hydrolysis half-lives at pH 7 are approximately 5 and 17 seconds. At physiologically-relevant conditions the calculated hydrolysis half-lives are expected to be faster.  

Table 2: Physicochemical properties

Property		Target substance		Source substance		Source substance
Substance name		trichloro(3,3,4,4,5,5,6,6,7,7,8,8,8-tridecafluorooctyl)silane		[2-(perfluorohexyl)ethyl]dichloro(methyl)silane		dichloromethyl(3,3,3-trifluoropropyl)silane
CAS number		78560-45-9		73609-36-6		675-62-7
Hydrolysis half-life at pH 7 and 25°C		5 seconds		5 seconds		< 17 seconds
Hydrolysis half-life at pH 7 and 37.5°C		<5 seconds		<5 seconds		< 17 seconds
Silanol hydrolysis product		[2-(perfluorohexyl)ethyl]silanetriol		[2‑(perfluorohexyl)ethyl]methylsilanediol		methyl(3,3,3-trifluoropropyl)silanediol
Non-Si hydrolysis products		hydrogen chloride		hydrogen chloride		hydrogen chloride
LogKow value (parent)		Not relevant		Not relevant		Not relevant
LogKow value (silanol hydrolysis product)		2.7 at 20°C (QSAR)		4.6 at 20°C (QSAR)		1.0
Vapour pressure (parent)		30 Pa at 25°C (QSAR)		0.04 Pa at 20°C, 30 Pa at 50°C (EU Method A.4)		740 Pa at 25°C (QSAR)
Vapour pressure (silanol hydrolysis product)		6.9E-03 Pa at 25°C (QSAR)		0.38 Pa at 25°C (QSAR)		1.3 Pa at 25°C (QSAR)
Water solubility (parent)		Not relevant		Not relevant		Not relevant
Water solubility (silanol hydrolysis product)		0.58 mg/l at 20°C (QSAR)		0.0048 mg/l at 20°C (QSAR)		1.35E+04 mg/l (very soluble) (QSAR)

3. AE A.3 Reliability and adequacy of the source study

There are no available data for in vitro genetic toxicity for the registered substance. Therefore, data were read-across from structurally analogous substances.

Dichloromethyl(3,3,3-trifluoropropyl)silane (CAS 675-62-7) has been tested for bacterial mutagenicity (Ames Test) in a study conducted according to a protocol similar to the OECD TG 471 which predates GLP (Dow Corning Corporation 1979). The Salmonella typhimurium strains TA 1535, TA 1537, TA 1538, TA 98, and TA 100 were exposed to the test material both in absence and presence of a metabolic activation system. An additional strain for the detection of cross-linking agents was not included into the test. No treatment related increase in the number of revertants was observed in any of the tester strains. Appropriate solvent and positive controls were included into the test and gave the expected results. Hence, the test item was considered to be non-mutagenic to bacteria under the conditions of the test.

Dichloromethyl(3,3,3-trifluoropropyl)silane (CAS 675-62-7) was tested for in vitro cytogenicity to mammalian cells according to the OECD TG 473 and in compliance with GLP (BSL BIOSERVICE, 2012b). The test item did not induce structural chromosomal aberrations in the V79 Chinese hamster cell line with and without metabolic activation up to cytotoxic concentrations. Appropriate positive and solvent controls were included into the study and gave the expected results. The test item is therefore considered to be non-clastogenic under the conditions of the test.

Dichloromethyl(3,3,3-trifluoropropyl)silane (CAS 675-62-7) has been tested for mutagenicity to mammalian cells in a study conducted according to OECD 476 and GLP (BSL BIOSERVICE, 2012a). No increase in mutant frequency was observed in the presence or absence of metabolic activation. It is concluded that, under the experimental conditions reported, the test substance is non-mutagenic in the in vitro mammalian cell gene mutation assay (thymidine kinase locus) in mouse lymphoma L5178Y cells.

4. AE A.4 Bias that influences the prediction

Data on the source substances, [2-(perfluorohexyl)ethyl]dichloro(methyl)silane (CAS 73609-36-6) and dichloromethyl(3,3,3-trifluoropropyl)silane (CAS 675-62-7), were read-across to the registered (target) substance trichloro(3,3,4,4,5,5,6,6,7,7,8,8,8-tridecafluorooctyl)silane (CAS 78560-45-9). The source substances and the target substance have similar chemical structure and physicochemical properties. All three substances are members of the analogue group of organosilicon substances with highly (but no fully) fluorinated side chains. The substances hydrolyse very rapidly to produce the corresponding Si-hydrolysis products and hydrochloric acid. None of the substances or hydrolysis products has structural alerts for genotoxicity (Benigni et al., 2008). The silanol hydrolysis products are also structurally similar. Therefore, the substances’ toxicological properties are expected to be similar, with similar genotoxic potential. No other data for relevant substances were available.

5. AE A.2.1 Compounds the test organism is exposed to

The source substances as well as the target substance hydrolyse at similar rate and very rapidly in contact with water. The rate of hydrolysis is fast in physiologically relevant conditions (approx. 5 seconds at pH7 and 37°C), therefore it is considered that the test organism would predominantely be exposed to the hydrolysis products. All three substances produce the same non-silanol hydrolysis product, hydrochloric acid, which is known for its corrosive properties. The silanol hydrolysis products for both substances are not expected to affect this assessment.

Hydrogen chloride gave negative results in the most reliable of the bacterial mutagenicity studies. Positive results were obtained in mutagenicity and cytogenicity assays using mammalian cells (OECD, 2002; ECHA disseminated dossier for hydrogen chloride). The positive results were associated with decrease in pH, and it is considered that the positive results were likely to have been caused by reduced pH. Positive results caused by high or low pH effects are considered not to be relevant for in vivo situations (ECHA guidance Chapter R.07a), and testing should be carried out at neutral pH.

6. AE A.2.2 and A.2.3 Common underlying mechanism, qualitative and quantitative aspects

No in vitro genetic toxicity data are available for the target substance trichloro(3,3,4,4,5,5,6,6,7,7,8,8,8-tridecafluorooctyl)silane (CAS 78560-45-9), therefore data are read-across from the structurally analogous substances [2-(perfluorohexyl)ethyl]dichloro(methyl)silane (CAS 73609-36-6) and dichloromethyl(3,3,3-trifluoropropyl)silane (CAS 675-62-7). Both substances hydrolyse very fast to produce acetic acid which has corrosive properties. The silanol hydrolysis products are not considered to be relevant for this endpoint. Moreover, they have similar physicochemical properties. Thus, both substances are expected to have similar toxicity profiles.

7. AE 2.4 Exposure to other compounds than to those linked to the prediction

The purity of the registration substance, trichloro(3,3,4,4,5,5,6,6,7,7,8,8,8-tridecafluorooctyl)silane (CAS 78560-45-9), is greater than 90 % with no impurities present at concentration greater than 1%.

Purity of test substance in the bacterial mutagenicity study with the source substance, [2-(perfluorohexyl)ethyl]dichloro(methyl)silane (CAS 73609-36-6), was reported to be 99.8%.

Purity of test substance in the bacterial mutagenicity study with the source substance, dichloromethyl(3,3,3-trifluoropropyl)silane (CAS 675-62-7), was not reported.

Purity of test substance in the mammalian cytogenicity study with the source substance, dichloromethyl(3,3,3-trifluoropropyl)silane (CAS 675-62-7), was reported to be 99.8%.

Purity of test substance in the mammalian mutagenicity study with the source substance, dichloromethyl(3,3,3-trifluoropropyl)silane (CAS 675-62-7), was reported to be 99.8%.

8. AE 2.5 Occurrence of Other Effects than Covered by the Hypothesis and Justification

Not relevant.

References:

Benigni and Bossa (2006). Current Computer-Aided Drug Design 2, (2), 169-176.

European Chemicals Agency (ECHA) (2015) Read-across Assessment Framework. Appendix B, Scenario 2.

Benigni et al (2008).The Benigni/Bossa rule base for mutagenicity and carcinogenicity JR Scientific report EUR 23241 EN.

OECD (2004b): SIDS Initial Assessment Report for SIAM 19, Berlin, Germany, 19-22 October 2004, Ethanol, CAS 64-17-5.

Justification for classification or non-classification

Based on the available read-across data on [2-(perfluorohexyl)ethyl]dichloro(methyl)silane and dichloromethyl(3,3,3-trifluoropropyl)silane, no classification is required for mutagenicity for [2-(perfluorohexyl)ethyl]trichlorosilane according to Regulation (EC) No. 1272/2008.