Registration Dossier

Administrative data

Key value for chemical safety assessment

Genetic toxicity in vitro

Description of key information

Gene mutation (Bacterial reverse mutation assay/ Ames test): negative with and without metabolic activation in S. typhimurium: TA 98, TA 100, TA 1535, TA 1537 and Escherichia coli: WP2 uvrA (according to EEC directive L251, 27, 137 1984).

Mammalian gene mutagenicity (in vitro mouse lymphoma L5178Y cell gene mutation test): read-across from structural analogue substance trichlorophenylsilane (CAS: 98-13-5): negative with and without metabolic activation. (according to OECD TG 476).

Mammalian cytogenicity (Chinese hamster lung fibroblasts V79 cell chromosome aberration assay): positive with metabolic activation (according to OECD TG 473).

Link to relevant study records

Referenceopen allclose all

Endpoint:
in vitro gene mutation study in bacteria
Type of information:
experimental study
Adequacy of study:
key study
Study period:
Not stated.
Reliability:
2 (reliable with restrictions)
Rationale for reliability incl. deficiencies:
test procedure in accordance with national standard methods with acceptable restrictions
Remarks:
The study was conducted according to an EU test method but full details are not available. It was compliant with GLP. The restrictions were that no units for concentration of the test material was provided and only the positive control with activation was not adequate to test S9 efficacy.
Qualifier:
according to
Guideline:
other: EEC directive L251, 27, 137 1984
Deviations:
yes
Remarks:
no Units for concentration of the test material was provided and the only positive control with activation was not adequate to test S9 efficacy.
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:
S. typhimurium TA 1535, TA 1537, TA 98 and TA 100
Species / strain / cell type:
E. coli WP2
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:
312.5, 625, 1250, 2500 and 5000 µg/plate - with and without metabolic activation.
Vehicle / solvent:
- Vehicle(s)/solvent(s) used: Ethanol.
Untreated negative controls:
no
Negative solvent / vehicle controls:
yes
True negative controls:
no
Positive controls:
yes
Positive control substance:
other: 2-Anthramine
Remarks:
with metabolic activation: All strains; 10 µg/plate
Untreated negative controls:
no
Negative solvent / vehicle controls:
yes
True negative controls:
no
Positive controls:
yes
Positive control substance:
methylmethanesulfonate
Remarks:
without metabolic activation:TA-1537; 50 µg/plate
Untreated negative controls:
no
Negative solvent / vehicle controls:
yes
True negative controls:
no
Positive controls:
yes
Positive control substance:
2-nitrofluorene
Remarks:
without metabolic activation: TA-98; 10 µg/plate
Untreated negative controls:
no
Negative solvent / vehicle controls:
yes
True negative controls:
no
Positive controls:
yes
Positive control substance:
9-aminoacridine
Remarks:
without metabolic activation: TA-1537; 50 µg/plate
Untreated negative controls:
no
Negative solvent / vehicle controls:
yes
True negative controls:
no
Positive controls:
yes
Positive control substance:
sodium azide
Remarks:
without metabolic activation: TA-1535, TA-100; 10 µg/plate
Details on test system and experimental conditions:
METHOD OF APPLICATION: in medium (plate incorporation)

DURATION
- Expression time (cells in growth medium): 72 hours

NUMBER OF REPLICATIONS: triplicates each in two independent experiments.

DETERMINATION OF CYTOTOXICITY
- Method: Not reported.

METABOLIC ACTIVATION SYSTEM: S-9 mix was prepared in accordance with published procedures (Ames, et al, 1975; Matsushima, et al, 1976), using a 9, 000 x g supernatant prepared from Sprague-Dawley adult male rat liver induced by Aroclor 1254 five days prior to kill.
Evaluation criteria:
Not reported
Statistics:
Not reported
Species / strain:
E. coli WP2
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
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:
not specified
Vehicle controls validity:
valid
Untreated negative controls validity:
not applicable
Positive controls validity:
valid
Additional information on results:
Not reported
Conclusions:
Interpretation of results: negative with and without metabolic activation

In a bacterial mutagenicity assay according to EEC directive L251, 27, 137 1984 and to GLP, no mutagenic effect was seen in any of the strains tested. Appropriate solvent and positive controls were included and gave expected results. The test substance is non-mutagenic in test strains used.
Endpoint:
in vitro cytogenicity / chromosome aberration study in mammalian cells
Type of information:
experimental study
Adequacy of study:
key study
Study period:
2008-05-15 to 2008-06-20
Reliability:
1 (reliable without restriction)
Rationale for reliability incl. deficiencies:
guideline study
Qualifier:
according to
Guideline:
OECD Guideline 473 (In Vitro Mammalian Chromosome Aberration Test)
Version / remarks:
1997
Deviations:
no
Qualifier:
according to
Guideline:
other: Commission Directive 2000/32/EC, L1362000, Annex 4A: ”Mutagenicity – In vitro Mammalian Chromosome Aberration Test“, dated May 19, 2000.
Deviations:
no
GLP compliance:
yes
Type of assay:
other: in vitro mammalian chromosome aberration test
Species / strain / cell type:
Chinese hamster lung fibroblasts (V79)
Metabolic activation:
with and without
Metabolic activation system:
cofactor supplemented post-mitochondrial fraction (S9 mix), prepared from the livers of rats treated with Phenobarbital/beta-Naphthoflavone.
Test concentrations with justification for top dose:
Without activation: 63.9-2045.0 µg/mL; with activation 31.9-1022.5 µg/mL
Vehicle / solvent:
- Vehicle(s)/solvent(s) used: ethanol
- Justification for choice of solvent/vehicle: The solvent was chosen for its solubility properties and its relative non-toxicity to the cell cultures.
Untreated negative controls:
no
Negative solvent / vehicle controls:
yes
True negative controls:
no
Positive controls:
yes
Positive control substance:
ethylmethanesulphonate
Remarks:
without metabolic activation: final concentration: 900 µg/mL
Untreated negative controls:
no
Negative solvent / vehicle controls:
yes
True negative controls:
no
Positive controls:
yes
Positive control substance:
cyclophosphamide
Remarks:
with metabolic activation: final concentration: 1.4 µg/mL
Details on test system and experimental conditions:
METHOD OF APPLICATION: in medium in Quadriperm dishes

DURATION
- Preincubation period: none
- Exposure duration: 4 hours
- Expression time (cells in growth medium): 14 hours
- Fixation time (start of exposure up to fixation or harvest of cells): 18 hours

SPINDLE INHIBITOR (cytogenetic assays):
STAIN (for cytogenetic assays): Giemsa

NUMBER OF REPLICATIONS: duplicate cultures (2 chambers per test group)

NUMBER OF CELLS EVALUATED: at least 100 per culture

DETERMINATION OF CYTOTOXICITY
- Method: mitotic index; other: reduced cell mumbers

OTHER EXAMINATIONS:
- Determination of polyploidy: yes
- Determination of endoreplication: yes

OTHER: a preliminary test to evaluate cytotoxicity was carried out to determine suitable dose range for the assay.
Evaluation criteria:
A test item is classified as clastogenic if:
a) the number of induced structural chromosome aberrations is not in the range of the laboratory’s historical control data range;
and b) either a concentration-related or a significant increase of the number of structural chromosome aberrations is observed.
Statistics:
Fisher’s exact test
Species / strain:
Chinese hamster lung fibroblasts (V79)
Metabolic activation:
with
Genotoxicity:
positive
Cytotoxicity / choice of top concentrations:
cytotoxicity
Remarks:
at 511.3 µg/mL and above with S9
Vehicle controls validity:
valid
Untreated negative controls validity:
not applicable
Positive controls validity:
valid
Species / strain:
Chinese hamster lung fibroblasts (V79)
Metabolic activation:
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 applicable
Positive controls validity:
valid
Additional information on results:
TEST-SPECIFIC CONFOUNDING FACTORS: none. A non-interfering precipitate was observed at 2055.0 µg/mL

RANGE-FINDING/SCREENING STUDIES: significant toxicity was observed in the preliminary cytotoxicity test at concentrations of 1022.5 and 2045.0 µg/mL

CYTOTOXICITY: cytotoxic concentrations did not produce sufficient cells with analysable chromosomes to be included in the analysis.


COMPARISON WITH HISTORICAL CONTROL DATA: control results fall within the range of historical controls. All values of cultures treated with test substance in the presence of metabolic activation showed increases in the number of cells with aberrations excluding gaps clearly exceeded the control values.

No polyploidy was observed in any culture

Table 1 Summary of results of chromosome aberration study

 Activation  Concentration µg/ml Cell numbers %   Mitotic index %  Aberrant cells inc gaps  Aberrant cells exc gaps Aberrant cells with exchanges 
Without activation Solvent control  100  100  2.5  1.0  0
Positive control  NT  115.4  15.5  12.5*  7.5
 127.8  103.1  138.5  1.5  1.5  0.5
 255.6  93.5  1.2.0  3.0  2.0  0
 511.3  89.3  102.4  0  0  0
With activation         Solvent control  100  100  2.5  2.5  0.5
 Positive control  NT  72.8  18.5  16.5*  7.5
 127.8  81.7  89.0  8.5  7.5*  5.5
 255.6  55.1  78.0  14.5  13.5*  6.5
 511.3  64.6  69.1  18.0  16.0*  5.0

NT not tested * Aberration frequency statistically significantly higher than corresponding control values (p < 0.05)                                                                                                                               

Table 2 Results of chromosome analysis without activation (total of 200 cells scored)


 Treatment    Solvent control  Positive control  Low dose 127.8 µg/mL Mid dose 255.6 µg/mL   High dose 511.3  µg/mL  
Cytotoxicity     no   no no  no 

no*

Chromatid aberrations 

 break

12 

 

fragment 

0  

 

deletion 

 

exchange 

21 

Chromosome aberrations 

break 

 0

 

fragment 

 

deletion 

 

exchange 

  0

mitotic index %    

100 

 115.4

138.5 

 102.0

102.4 

*cultures treated with toxic concentrations did not have sufficient analysable chromosomes to be included in the analysis

Table 3 Results of chromosome analysis with activation (total of 200 cells scored)

 Treatment  

Solvent control 

Positive control 

Low dose 127.8 µg/mL

Mid dose 255.6 µg/mL 

High dose 511.3 µg/mL 

Cytotoxicity    

no 

 no

no 

 no

 no

Chromatid aberrations 

 break

19 

16 

25 

 

fragment 

 

deletion 

 

exchange 

15

11 

15 

10 

Chromosome aberrations 

break 

 

fragment 

 

deletion 

 

exchange 

mitotic index  %  100 72.8   89.0  78.0  69.1
Conclusions:
Interpretation of results :
positive with metabolic activation
negative without metabolic activation

Trimethoxyphenylsilane CAS 2996-92-1 has been tested in a valid in vitro cytogenicity study according to OECD 473 and under GLP. A statistically significant, dose dependent increase in the number of cells with aberrations excluding gaps was detected in the evaluated concentration tested in the presence of activation. Appropriate solvent and positive controls were included and gave expected results. It is concluded by the authors of the study that this result is biologically significant and that trimethoxyphenylsilane is positive for the induction of structural chromosome aberrations (clastogenic) under the conditions of the test.
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:
read-across source
Species / strain:
mouse lymphoma L5178Y cells
Metabolic activation:
with and without
Genotoxicity:
negative
Cytotoxicity / choice of top concentrations:
cytotoxicity
Remarks:
600 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

Executive summary:

An in vitro mammalian mutagenicity study is available from the structural analogue trichloro(phenyl)silane. In this test the structural analogue did not show any genotoxic potential and thus this is also estimated for trimethoxy(phenyl)silane. As explained in the justification for type of information, the differences in molecular structure between the target and the source are unlikely to lead to differences in genetic toxicity that are higher than the typical experimental error of the test method.

Endpoint conclusion
Endpoint conclusion:
adverse effect observed (positive)

Genetic toxicity in vivo

Description of key information

Chromosome aberration (rat erythrocyte micronucleus assay, inhalation: vapour): read-across from the structural analogue substance dimethoxymethylphenylsilane (CAS: 3027-21-2): negative (according to OECD TG 413).

Link to relevant study records
Reference
Endpoint:
in vivo mammalian somatic cell study: cytogenicity / erythrocyte micronucleus
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:
read-across source
Sex:
male/female
Genotoxicity:
negative
Toxicity:
yes
Remarks:
reduction in PCE:NCE ratio relative to control
Vehicle controls validity:
valid
Negative controls validity:
valid
Positive controls validity:
not examined
Conclusions:
Interpretation of results: negative
Executive summary:

An in vivo mammalian micronucleus study is available from the structural analogue dimethoxymethyl(phenyl)silane CAS 3027 -21 -2. In this test the structural analogue did not show any genotoxic potential and thus this is also estimated for trimethoxy(phenyl)silane. As explained in the justification for type of information, the differences in molecular structure between the target and the source are unlikely to lead to differences in genetic toxicity that are higher than the typical experimental error of the test method.

Endpoint conclusion
Endpoint conclusion:
no adverse effect observed (negative)

Additional information

Studies were chosen as key when the available study was of relevance and of sufficient quality for classification, labelling and for risk assessment.

 

The key bacterial mutagenicity study on trimethoxyphenylsilane was conducted in compliance with GLP and according to EEC directive L251, 27, 137, 1984 (now B.13/14). No evidence for a test-substance related increase in the number of revertants was observed in Salmonella typhimurium TA 98, TA 100, TA 1535, TA 1537 and Escherichia coli WP2 and WP2 uvrA strains. Appropriate positive and solvent controls were included and gave expected results. Under the conditions of this study, trimethoxyphenylsilane was concluded to be non-mutagenic in the Salmonella typhimurium/E. coli strains (Dow Corning Corporation, 1991a).

 

No measured data are available to assess the in vitro mammalian mutagenicity potential of the registered substance, trimethoxyphenylsilane, however, reliable data are available for the structural analogue substance, trichlorophenylsilane (CAS: 98-13-5). Both substances hydrolyse in contact with water to generate the common silanol hydrolysis product, phenylsilanetriol, and it is therefore considered that read-across between the substances is appropriate. The other hydrolysis products, methanol and hydrogen chloride are not genotoxic.

The key in vitro cytogenicity study on trimethoxyphenylsilane was conducted in compliance with GLP and according to OECD TG 473. A statistically significant, dose dependent increase in the number of cells with aberrations excluding gaps was detected in the evaluated concentration in the presence of metabolic activation.Appropriate positive and solvent controls were included and gave expected results.It was therefore concluded that this result is biologically significant and that trimethoxyphenylsilane is positive for the induction of structural chromosome aberrations (clastogenic) under the conditions of the test (Hoffmann, H.2008).

The key in vitro mammalian cell gene mutation study on the structural analogue substance trichlorophenylsilane (CAS: 98-13-5) was conducted in compliance with GLP and according to OECD TG 476. No increase in mutant frequency was observed at any concentration with and without metabolic activation at 4 hours treatment and without metabolic activation at 24 hours 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 (Flanders, L.2010).

 

 

No measured data are available to assess the in vivo cytogenicity potential of the registered substance, trimethoxyphenylsilane, however reliable data are available for the structural analogue substance dimethoxymethylphenylsilane (CAS: 3027-21-2). Since both substances hydrolyse in contact with water to generate structurally related silanol hydrolysis products,phenylsilanetriol and methylphenylsilanediol, it is considered that read-across between the substances is appropriate. The other hydrolysis products, methanol is not genotoxic.

 

The key in vivo cytogenicity study on the structural analogue substance dimethoxymethylphenylsilane (CAS: 3027-21-2)wasperformed as part of a 14-day repeat dose inhalation toxicity study in compliance with GLP and according to OECD TG 413. The test substance was not genotoxic under the conditions of the test. Appropriate positive and solvent controls were included and gave expected results (Dow Corning Corporation, 1991b). The potential for clastogenicity observed in the in vitro assay with the registered substance was not confirmed in an in vivo chromosome aberration assay with the structural analogue substance dimethoxymethylphenylsilane, therefore the overall assumption is that the registered substance is neither mutagenic not cytogenic. 


Justification for classification or non-classification

Based on the available in vitro and in vivo data on mutagenicity of the registered substance and the structural analogue substances, trichlorophenylsilane (CAS: 98-13-5) and dimethoxymethylphenylsilane (CAS: 3027-21-2), trimethoxyphenylsilane is not classified for mutagenicity according to Regulation (EC) 1272/2008 or Directive 67/548/EEC.