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Diss Factsheets

Administrative data

Key value for chemical safety assessment

Genetic toxicity in vitro

Description of key information

Gene mutation (Bacterial reverse mutation assay / Ames test, R/A from CAS 16415-12-6 and CAS 2943-75-1): S. typhimurium TA 98, TA 100, TA 1535, TA 1537, and E. coli WP2 uvrA: negative with and without metabolic activation (OECD 471, GLP)
Mammalian cytogenicity (Chromosome Aberration, R/A from CAS 16415-12-6 and CAS 2943-75-1): negative with and without metabolic activation (OECD 473, GLP)
Mammalian mutagenicity (Mouse lymphoma assay, R/A from CAS 2943-75-1): negative with and without metabolic activation (OECD 476, GLP)

Link to relevant study records

Referenceopen allclose all

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
Key result
Species / strain:
mouse lymphoma L5178Y cells
Metabolic activation:
with and without
Genotoxicity:
negative
Cytotoxicity / choice of top concentrations:
cytotoxicity
Remarks:
RTG of 14.6% and 9.7% without metabolic activation.
Vehicle controls validity:
valid
Untreated negative controls validity:
valid
Positive controls validity:
valid
Remarks on result:
other: CAS 2943-75-1, BSL, 2012
Conclusions:
Interpretation of results: negative

Triethoxyoctylsilane has been tested for mutagenicity to mammalian cells in a reliable study conducted according to OECD TG 476 and in compliance with GLP. No biologically relevant increase in mutation rate was found in mouse lymphoma L5178Y cells with or without metabolic activation in either the initial or the repeat experiment, up to limit and cytotoxic concentrations. As explained in the analogue justification, it is considered that the target and the source substances are unlikely to lead to differences in genetic toxicity potential.
Endpoint:
in vitro gene mutation study in bacteria
Type of information:
read-across from supporting substance (structural analogue or surrogate)
Remarks:
Summary of available data used for the endpoint assessment of the target substance
Adequacy of study:
weight of evidence
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
Reason / purpose for cross-reference:
read-across source
Key result
Species / strain:
S. typhimurium, other: TA 1535, TA 1537, TA 98 and TA 100
Metabolic activation:
with and without
Genotoxicity:
negative
Cytotoxicity / choice of top concentrations:
no cytotoxicity nor precipitates, but tested up to recommended limit concentrations
Vehicle controls validity:
valid
Untreated negative controls validity:
not examined
Positive controls validity:
valid
Key result
Species / strain:
E. coli WP2 uvr A
Metabolic activation:
with and without
Genotoxicity:
negative
Cytotoxicity / choice of top concentrations:
no cytotoxicity nor precipitates, but tested up to recommended limit concentrations
Vehicle controls validity:
valid
Untreated negative controls validity:
not examined
Positive controls validity:
valid
Remarks on result:
other: CAS 16415-12-6, Evonik, 2011
Conclusions:
Interpretation of results: negative

In a study according to OECD 471 and in compliance with GLP no mutagenic effect was observed for the source substances tested up to the limit concentration in any of the test strains in three independent experiments with and without metabolic activation. As explained in the analogue justification, it is considered that the target and the source substances are unlikely to lead to differences in genetic toxicity potential.
Endpoint:
in vitro cytogenicity / chromosome aberration study in mammalian cells
Type of information:
read-across from supporting substance (structural analogue or surrogate)
Remarks:
Summary of available data used for the endpoint assessment of the target substance
Adequacy of study:
weight of evidence
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
Reason / purpose for cross-reference:
read-across source
Key result
Species / strain:
Chinese hamster Ovary (CHO)
Metabolic activation:
with and without
Genotoxicity:
negative
Cytotoxicity / choice of top concentrations:
no cytotoxicity nor precipitates, but tested up to recommended limit concentrations
Vehicle controls validity:
valid
Untreated negative controls validity:
not examined
Positive controls validity:
valid
Key result
Species / strain:
Chinese hamster Ovary (CHO)
Metabolic activation:
with and without
Genotoxicity:
negative
Cytotoxicity / choice of top concentrations:
cytotoxicity
Remarks:
at 20 µg/mL (- S9-mix); 50 µg/mL (+ S9-mix)
Vehicle controls validity:
valid
Untreated negative controls validity:
valid
Positive controls validity:
valid
Remarks on result:
other: CAS 16415-12-6, RTC, 2005
Conclusions:
Interpretation of results: negative

The source substances were tested according to OECD 473 under GLP. The source substances did not induce any statistically significant, dose-related increases in the frequency of cells with chromosomal aberrations either in the presence or absence of metabolic activation or after various exposure times. The source substances were therefore considered to be non-clastogenic to Chinese Hamster Ovary (CHO) cells in vitro under the conditions of the tests. As explained in the analogue justification, it is considered that the target and the source substances are unlikely to lead to differences in genetic toxicity potential.
Endpoint conclusion
Endpoint conclusion:
no adverse effect observed (negative)

Genetic toxicity in vivo

Endpoint conclusion
Endpoint conclusion:
no study available

Additional information

No data on genetic toxicity in mammalian cells in vitro is available for triethoxyhexadecylsilane (CAS 16415-13-7). Therefore, the risk assessment was performed based on the available data from the source substances triethoxy(octyl)silane (CAS 2943-75-1) and hexadecyltrimethoxysilane (CAS 16415-12-6). In accordance with Regulation (EC) No. 1907/2006 Annex XI, 1.5 “Grouping of substances and read across” and following the Read across assessment framework (RAAF, ECHA 2017) read across from analogue substances has been applied to support the human health hazard assessment of triethoxyhexadecylsilane (CAS 16415-13-7).

Overview of genetic toxicity

CAS

16415-13-7 (a)

16415-12-6 (b)

2943-75-1 9 (b)

Chemical name

Triethoxyhexadecylsilane

Hexadecyltrimethoxysilane

Triethoxyoctylsilane

Molecular weight

388.34 g/mol

346.62 g/mol

g/mol

Bacterial mutagenicity

RA 16415-12-6

RA 2943-75-1

Experimental result: negative

Experimental result: negative

Mammalian cytogenicity

RA 16415-12-6

RA 2943-75-1

Experimental result: negative

Experimental result: negative

Mammalian mutagenicity

RA 2943-75-1

No data

Experimental result: negative

(a) The substance subject to registration is indicated in bold font.

(b) Reference (read-across) substances are indicated in normal font.

 

The above mentioned substances are considered to be similar on the basis of the structural similar properties and/or activities. The available endpoint information is used to predict the same endpoints for Triethoxyhexadecylsilane (CAS 16415-13-7). A detailed supporting report is provided in the target entry.

Discussion

Genetic toxicity (mutagenicity) in bacteria in vitro

A reliable bacterial gene mutation study (Ames test) performed according to OECD TG 471 and in compliance with GLP with hexadecyltrimethoxysilane (CAS 16415-12-6) is available (Evonik, 2011). The strains Salmonella typhimurium TA 1535, TA 1537, TA 98, TA 100 and E. coli WP2 uvrA were tested according to the plate incorporation procedure in the absence and presence of a metabolic activation system (Aroclor 1254-induced rat liver S9-mix). Two independent experiments were conducted in three repetitions at each concentration from 62 to 5000 µg/plate (experiment I) and 1000 to 5000 µg/plate (experiment II). No cytotoxicity was observed with the test item up to 5000 µg/plate in the absence and presence of metabolic activation. Precipitation was recorded at concentrations of ≥1000 µg/plate. Appropriate solvent (acetone) and positive controls were included and gave the expected results. No significant increase in the number of revertants was observed in any of the tester strains with and without metabolic activation. Therefore, the test material was considered to be non-mutagenic under the conditions of the test.

 

A further reliable bacterial gene mutation study (Ames test) performed according to OECD TG 471 and in compliance with GLP with triethoxyoctylsilane (CAS 2943-75-1) is available (MA Bioservices, 1998). The strains Salmonella typhimurium TA 1535, TA 1537, TA 98, TA 100 and E. coli WP2 uvrA were tested according to the pre-incubation procedure in the absence and presence of a metabolic activation system (Aroclor 1254-induced rat liver S9-mix). Two independent experiments were conducted in three repetitions at each concentration from 75 to 5000 µg/plate. No cytotoxicity was observed with the test item up to 5000 µg/plate in the absence and presence of metabolic activation. Precipitation was recorded at concentrations of ≥1000 µg/plate. Appropriate solvent (acetone) and positive controls were included and gave the expected results. No significant increase in the number of revertants was observed in any of the tester strains with and without metabolic activation. Therefore, the test material was considered to be non-mutagenic under the conditions of the test.

 

Genetic toxicity (cytogenicity) in mammalian cells in vitro

In the chromosome aberration assay, performed according to OECD TG 473 and in compliance with GLP, Chinese Hamster Ovary (CHO) cells were treated with hexadecyltrimethoxysilane (CAS 16415-12-6) at concentrations from 10.2 to 1300 µg/mL in the presence and absence of metabolic activation (RTC, 2005). The cells were treated for 3 h (with and without metabolic activation, experiment I) and for 20 h (without metabolic activation, experiment II). After 20 h the cells were fixed and stained with Giemsa after previous exposure to the spindle inhibitor colcemid. Appropriate solvent (ethanol) and positive controls were included and gave the expected results. Cytotoxicity was recorded at concentrations ≥20.3 µg/mL (20 h exposure) in the absence of metabolic activation. The test material did not induce any statistically significant, dose-related increases in the frequency of cells with chromosomal aberrations either in the presence or absence of metabolic activation or after various exposure times. The test material was therefore considered to be non-clastogenic to CHO cells in vitro under the conditions of the test.

 

In a further chromosome aberration assay, performed according to OECD TG 473 and in compliance with GLP, Chinese Hamster Ovary (CHO), cells were treated with triethoxyoctylsilane (CAS 2943-75-1) at concentrations from 8.5 to 20 µg/mL (6 h exposure, without metabolic activation), 21.3 to 50 µg/mL (6 h exposure, with metabolic activation) and 8.5 to 20 µg/mL (24 and 48 h exposure, without metabolic activation) in the presence or absence of metabolic activation (MA Bioservices, 1997). After appropriate incubation time the cells were fixed and stained with Giemsa after previous exposure to the spindle inhibitor colcemid (0.1 µg/mL). Appropriate solvent (ethanol) and positive controls were included and gave the expected results. No cytotoxicity was observed up to limit concentrations. The test substance did not induce statistically and biologically significant increases in the chromosomal aberration frequency of CHO (Chinese hamster ovary) cells. It is therefore concluded that the test substance is negative for the induction of chromosome aberrations (not clastogenic) in vitro under the conditions of the test.

 

Genetic toxicity (mutagenicity) in mammalian cells in vitro

An in vitro Mammalian Cell Gene Mutation Test was performed with triethoxyoctylsilane (CAS 2943-75-1) in mouse lymphoma L5178Y cells (heterozygous at the thymidine kinase locus) according to OECD TG 476 and under GLP (BSL, 2012). The cells were treated with the test substance in quadruplicates, together with vehicle (THF) and positive controls. 4 hour exposures were used both with (phenobarbital and ß-naphthoflavone-induced rat liver S9-mix) and without metabolic activation in Experiment l and with metabolic activation in Experiment II. In Experiment II, the exposure time without metabolic activation was increased to 24 hours. The dose range of test material in the first experiment was 0.1 to 10 mM following the results of a preliminary toxicity test with evidence of toxicity at concentrations ≥0.5 mM in the absence of metabolic activation. Experiment II was performed using the dose range of 0.15 to 10 mM with metabolic activation and 0.001 to 0.20 mM without metabolic activation. A precipitate of test material was observed in Experiment I with (10 mM) and without (≥7.5 mM) metabolic activation and in Experiment II with (≥8.0 mM) metabolic activation. Evident cytotoxicity was observed in Experiment I at concentrations ≥1.0 mM in the absence of metabolic activation. In Experiment II, marked cytotoxicity was recorded at concentrations of 2.0 and 6.0 mM in the presence of metabolic activation and at concentrations ≥0.10 mM in the absence of metabolic activation. The vehicle controls had acceptable mutant frequency values that were within the normal range for the L5l78Y cell line at the TK locus. The positive control materials induced marked increases in the mutant frequency indicating the satisfactory performance of the test and of the activity of the metabolising system. The test material did not induce any biologically relevant increase in the mutant frequency at any dose level in any of the exposure groups. Additionally, in Experiments I and II colony sizing showed no clastogenic effects induced by the test item under the experimental conditions (with and without metabolic activation). Thus, the test material was considered to be non-mutagenic or clastogenic to L5178Y cells under the conditions of the test.

 

Based on the available data on genetic toxicity in vitro with the read-across substances hexadecyltrimethoxysilane (CAS 16415-12-6) and triethoxyoctylsilane (CAS 2943-75-1) sufficient evidence is available to conclude that the registration substance triethoxyhexadecylsilane (CAS 16415-13-7) is neither mutagenic in bacterial and mammalian cells nor clastogenic in mammalian cells.

Justification for classification or non-classification

Reliable data from a structural analogue and the registration substance on genetic toxicity indicate that Triethoxyhexadecylsilane do not meet the criteria for classification according to Regulation (EC) No 1272/2008, and the available data are therefore conclusive but not sufficient for classification.