2,4-Hexadienoic acid, 3-(trimethoxysilyl)propyl ester, (2E,4E)-

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 metabolic activation in Salmonella typhimurium TA 1535, TA 1537, TA 98, TA 100 and E. coli WP2 (OECD 471, 1997) (BSL Bioservice, 2012e).

Cytogenicity in mammalian cells: negative with and without metabolic activation in cultured human lymphocytes (OECD 473, 1997) (BSL Bioservice, 2013b).

Mutagenicity in mammalian cells: positive with metabolic activation in L5178Y mouse lymphoma cells (OECD 476, 1997) (BSL Bioservice, 2013c).

Link to relevant study records

Reference

Reference 1

Endpoint:

in vitro gene mutation study in bacteria

Remarks:

Type of genotoxicity: gene mutation

Type of information:

experimental study

Adequacy of study:

key study

Study period:

23 January - 14 May, 2012

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

Qualifier:

according to guideline

Guideline:

EPA OPPTS 870.5100 - Bacterial Reverse Mutation Test (August 1998)

Deviations:

no

GLP compliance:

yes (incl. QA statement)

Type of assay:

bacterial reverse mutation assay

Target gene:

All Salmonella strains contain mutation, in the histidine operon, thereby imposing a requirement for histidine in the growth medium. They contain the deep rough (rfa) mutation which deletes the polysaccharide side chain of the lipopolysaccharides of the bacterial cell surface. This increases cell permeability of larger substances. The other mutation is a deletion of the uvrB gene coding for a protein of the DNA nucleotide
excision repair system resulting in an increased sensitivity in detecting many mutagens. This deletion also includes the nitrate reductase (chl) and biotin (bio) gene. (Bacteria require biotin for growth).
The tester strains TA 98 and TA 100 contain the R·factor plasmid, pkM101. These strains are reverted by a number of mutagens that are detected weakly or not at all with the non R-factor parent strains. pkM101 increases chemical and spontaneous mutagenesis by enhancing an error-prone DNA repair system which is normally present in these organisms.
The tester strain E. coli WP2 uvrA carries the defect in one of the genes for tryptophan biosynthesis. Tryptophan-independent mutants (revertants) can arise either by a base change at the site of the original alteration or by a base change elsewhere in the chromosome so that the original defect is suppressed. This second possibility can occur in several different ways so that the system seems capable of detecting all types of mutagen, which substitute one base for another. Additionally, the strain is deficient in the DNA nucleotide excision repair system.

The properties of the S. typhimurium and E. coli strains, with regard to membrane permeability, ampicillin- and tetracycline-resistance as well as normal spontaneous mutation rates are cheeked regularly according to Ames et al. In this way it is ensured that the experimental conditions set up by Ames are fulfilled.

Species / strain / cell type:

S. typhimurium TA 1535, TA 1537, TA 98, TA 100 and E. coli WP2

Additional strain / cell type characteristics:

not specified

Metabolic activation:

with and without

Metabolic activation system:

Phenobarbital (80 mg/kg bw) and β-naphthoflavone (100 mg/kg bw) induced rat liver S9.

Test concentrations with justification for top dose:

Exposure Concentrations
The test item concentrations to be applied in the main experiments were chosen according to the results of the pre-experiment. 5000 µg/plate was selected as the maximum concentration. The concentration range covered two logarithmic decades. Two independent experiments were performed at the following concentrations:

Experiment I (plate incorporation method):
31.6, 100, 316, 1000, 2500 and 5000 µg/plate

Experiment II (pre-incubation method):
10.0, 31.6, 100, 316, 1000, 2500 and 5000 µg/plate

As the results of the pre-experiment were in accordance with the criteria described above, these were reported as a part of the main Experiment I.

Vehicle / solvent:

- Vehicle(s)/solvent(s) used: DMSO
- Justification for choice of solvent/vehicle: miscible and stable in DMSO

Untreated negative controls:

yes

Remarks:

A. dest., BSL Bioservice Lot No, 120203, 120221

Negative solvent / vehicle controls:

yes

Remarks:

DMSO, AppliChem Lot No. IP008076, I Y009099

True negative controls:

no

Positive controls:

yes

Positive control substance:

sodium azide

methylmethanesulfonate

other: 4-nitro-o-phenylene-diamine; 2-aminoanthacene

Remarks:

Pos. control substances assigned to different tester strains.

Details on test system and experimental conditions:

ACTIVATION: Phenobarbital (80 mg/kg bw) and β-naphthoflavone (100 mg/kg bw) induced rat liver S9. S9 mix included 5% S9, with MgCl₂, KCl, glucose-6-phosphate and NADP. 500 μl of S9 mix were included in 2.7 ml agar, test solution and bacterial suspension, giving a final concentration of approximately 1% S9 in the plates.

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

DURATION
- Preincubation period (second experiment): 60 minutes
- Exposure duration: at least 48 hours

SELECTION AGENT (mutation assays): histidine or tryptophan deficient agar

NUMBER OF REPLICATIONS: triplicate plates. The initial plate incorporation assay was repeated in an independent experiment using the pre-incubation method.

DETERMINATION OF CYTOTOXICITY
- Method: mitotic index; cloning efficiency; relative total growth; other: clearing or diminution of background lawn or reduction in number of revertants to ≤ 0.5 relative to solvent control

Evaluation criteria:

A test item is considered mutagenic if a clear dose-related increase in the number of revertants occurs, and/or there is a biologically relevant response for at least on dose group in at least one strain with or without metabolic activation.

Statistics:

Not required.

Key result

Species / strain:

S. typhimurium TA 1535, TA 1537, TA 98, TA 100 and E. coli WP2

Metabolic activation:

with and without

Genotoxicity:

negative

Cytotoxicity / choice of top concentrations:

cytotoxicity

Remarks:

reduction in background lawn was observed at concentrations of 1000 μg/plate and above. A reduction in the number of revertants to 50% of solvent control was observed in several strains. This was not considered biologically relevant.

Vehicle controls validity:

valid

Untreated negative controls validity:

valid

Positive controls validity:

valid

Remarks on result:

other: all strains/cell types tested

Remarks:

Migrated from field 'Test system'.

Results of Experiment 1 (plate incorporation) and Experiment 2 (pre-incubation). Revertants per plate (mean of three plates)

	Experiment 1 (plate incorporation)
Concentration μg/plate (solvent or control substance)	TA98		TA100		TA1535		TA1537		E. coli WP2
	-MA	+MA	-MA	+MA	-MA	+MA	-MA	+MA	-MA	+MA
0 (distilled water)	22	27	101	115	5	7	9	10	41	50
0 (DMSO)	18	25	90	113	6	6	6	7	33	47
31.6	19	26	98	112	7	12	6	10	38	31
100	19	32	92	115	9	8	7	11	44	45
316	21	34	91	126	2	9	10	13	42	55
1000	23	42	80*	110	4*	10	7*	8	39*	58
2500	22	25	59*	104	4*	7	6*	9	38*	49
5000	22	28	70*	82	3*	8	3*	8	27*	47
10 (4-NOPD)	390	-	-	-	-	-	140	-	-	-
10 (NaN₃)	-	-	850	-	803	-	-	-	-	-
1 μl (MMS)	-	-	-	-	-	-	-	-	340	-
2.5 (2-AA)	-	2659	-	2075	-	126	-	213	-	133
	Experiment 2 (pre-incubation)
Concentration μg/plate (solvent or control substance)	TA98		TA100		TA1535		TA1537		E. coli WP2
	-MA	+MA	-MA	+MA	-MA	+MA	-MA	+MA	-MA	+MA
0 (distilled water)	23	29	128	125	7	5	6	7	77	60
0 (DMSO)	19	24	107	110	5	9	4	7	51	49
10	23	34	113	93	8	8	7	3	46	55
31.6	20	25	114	110	9	6	5	5	55	56
100	23	28	109	98	5	4	7	6	53	63
316	21	28	85	108	6	7	7	3	50	46
1000	21	29	62*	106	2*	7	5*	6	52	56
2500	17	31	55*	102*	1*	8	4*	10	40	56
5000	19	28	67*	83*	3*	5*	4*	8*	38	49
10 (4-NOPD)	446	-	-	-	-	-	86	-	-	-
10 (NaN₃)	-	-	839	-	577	-	-	-	-	-
1 μl (MMS)	-	-	-	-	-	-	-	-	710	-
2.5 (2-AA)	-	1985	-	1543	-	57	-	185	-	161

* Reduction in background lawn

4-NOPD  4-nitro-o-phenylene-diamine

NaN₃      sodium azide

MMS      methylmethanesulfonate

2-AA      2-aminoanthacene

Conclusions:

Interpretation of results (migrated information):
negative with and without metabolic activation

In conclusion, it can be stated that during the described mutagenicity test and under the experimental conditions reported, the test item did not cause gene mutations by base pair changes or frame shifts in the genome of the tester strains used. Appropriate positive, solvent and negative controls were included and gave expected results. Therefore, the test item is considered to be non-mutagenic in this bacterial reverse mutation assay under the conditions of the test.

Executive summary:

The test item was investigated for its potential to induce gene mutations according to the plate incorporation test (Experiment I) and the pre-incubation test (Experiment II) using Salmonella typhimurium strains TA 98, TA 100, TA 1535, TA 1537 and tester strain E. coli WP2 uvrA. In two independent experiments several concentrations of the test item were used. Each assay was conducted with and without metabolic activation. The concentrations, including the controls, were tested in triplicate. The following concentrations of the test item were prepared and used in the experiments: Experiment I (plate incorporation method): 31.6, 100, 316, 1000, 2500 and 5000 μg/plate Experiment II (pre-incubation method): 10.0, 31.6, 100, 316, 1000, 2500 and 5000 μg/plate

No precipitation of the test item was observed in any tester strain used in Experiment I and II (with and without metabolic activation). Cytotoxicity related to clearing or rather diminution of the background lawn and a reduction in the number of revertants down to a mutation factor equal and less than 0.5 in relation to the solvent control was noted in both experiments. Cytotoxicity was noted in four tester strains used in Experiment I and in three tester strains used in Experiment II. In Experiment I, reduced background lawn was observed in four tester strains (TA 100, TA 1535, TA 1537 and WP2 uvrA) at concentrations greater than or equal to 1000 μg/plate (without metabolic activation). In strain TA 1537, the mutation factor was 0.5 at 5000 μg/plate. One other strain TA1535 (without metabolic activation) had one concentration, 316 μg/plate, with a mutation factor less than 0.5. However, the finding is not considered to be biologically relevant, because it did not appear to be attributable to the test item. In Experiment II, reduced background lawn was observed in three tester strains (TA 100, TA 1535, and TA 1537) at concentrations of 1000 μg/plate and higher (without metabolic activation). With metabolic activation, two of same three strains (TA 1535, and TA 1537) had reduced background lawn at a concentration of 5000 μg/plate. The remaining strain (TA 100) had reduced background lawn concentrations greater than or equal to 2500 μg/plate. A mutation factor of 0.5 and less was noted at various concentrations for TA 100 (without metabolic activation), TA 1535 (with and without metabolic activation), and TA 1537 (with metabolic activation). However with the exception of strain TA 1535 (without metabolic activation) where the mutation factor was equal to or less than 0.5 at the three highest concentrations tested, the finding was not considered to be biologically relevant due to its sporadic incidence. No biologically relevant increases in revertant colony numbers of any of the five tester strains were observed following treatment with 2,4 -hexadienoic acid, 3-(trimethoxysilyl) propyl ester at any concentration level, neither in the presence nor absence of metabolic activation in Experiment I and II. The reference mutagens induced a distinct increase of revertant colonies indicating the validity of the experiments. In conclusion, it can be stated that during the described mutagenicity test and under the experimental conditions reported, the test item did not cause gene mutations by base pair changes or frameshifts in the genome of the tester strains used. Therefore, the test item is considered to be non-mutagenic in this bacterial reverse mutation assay.

Reference 2

Endpoint:

in vitro cytogenicity / chromosome aberration study in mammalian cells

Remarks:

Type of genotoxicity: chromosome aberration

Type of information:

experimental study

Adequacy of study:

key study

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

Remarks:

however, the number of cells scored for aberrations was lower than required in the 2014 guideline

Qualifier:

according to guideline

Guideline:

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

Deviations:

no

Qualifier:

according to guideline

Guideline:

EPA OPPTS 870.5375 - In vitro Mammalian Chromosome Aberration Test

GLP compliance:

yes (incl. QA statement)

Type of assay:

in vitro mammalian chromosome aberration test

Species / strain / cell type:

lymphocytes:

Details on mammalian cell type (if applicable):

The cells were obtained from blood samples from healthy donors not receiving medication.

Metabolic activation:

with and without

Metabolic activation system:

Phenobarbital and β-naphthoflavone induced rat liver S9.

Test concentrations with justification for top dose:

Experiment I: tested concentrations: 0.25-5.00 mM (-MA), 1.00-10.00 mM (+MA); evaluated concentrations: 0.50, 1.00, 1.75 mM (-MA), 1.00 2.50, 7.50 mM (+MA)
Experiment II: tested concentrations: 0.10-10.00 mM (-MA), 0.40-10.00 mM (+MA); evaluated concentrations 0.19, 0.47, 1.0 mM (-MA), 2.00, 6.00, 8.00 mM (+MA)

Vehicle / solvent:

- Vehicle(s)/solvent(s) used: DMSO;
- Justification for choice of solvent/vehicle: DMSO was selected as solvent following a solubility test and as a result of further formulation analysis.

Untreated negative controls:

yes

Remarks:

treatment medium

Negative solvent / vehicle controls:

yes

Remarks:

DMSO

True negative controls:

no

Positive controls:

yes

Positive control substance:

N-dimethylnitrosamine

ethylmethanesulphonate

Remarks:

without metabolic activation 400 and 900 µg/ml

Untreated negative controls:

yes

Remarks:

treatment medium

Negative solvent / vehicle controls:

yes

Remarks:

DMSO

True negative controls:

no

Positive controls:

yes

Positive control substance:

cyclophosphamide

Remarks:

with metabolic activation 5 µg/ml

Details on test system and experimental conditions:

ACTIVATION: Phenobarbital and β-naphthoflavone induced rat liver S9, protein concentration 47.7 mg/ml. S9 mix included 5% S9, with MgCl₂, KCl, glucose-6-phosphate and NADP. The final protein concentration in the cultures was 0.75 mg/ml S9.

METHOD OF APPLICATION: in medium

DURATION
- Exposure duration: 4 hours (with and without metabolic activation, experiment I; with metabolic activation, experiment II); 24 hours (without metabolic activation, experiment II).
- Fixation time (start of exposure up to fixation or harvest of cells): 24 hours

SPINDLE INHIBITOR (cytogenetic assays): Colcemid
STAIN (for cytogenetic assays): Giesma

NUMBER OF REPLICATIONS: Cultures were duplicated. The initial experiment with 4 hour treatment was repeated using 24 hours exposure time without metabolic activation.

NUMBER OF CELLS EVALUATED: 200 cells per concentration were evaluated for aberrations. The mitotic index was determined in 1000 cells per culture

DETERMINATION OF CYTOTOXICITY
- Method: mitotic index

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

Evaluation criteria:

Criteria for determining a positive result:
- a clear and dose-related increase in the number of cells with aberrations.
- a biologically relevant for at least one of the dose groups, higher than the laboratory negative control range.

Key result

Species / strain:

lymphocytes:

Metabolic activation:

with and without

Genotoxicity:

negative

Cytotoxicity / choice of top concentrations:

cytotoxicity

Remarks:

Experiment I: 1.75 mM (-MA), 7.5 mM (+MA); Experiment II: 1.00 mM (-MA), 6.00 mM (+MA)

Vehicle controls validity:

valid

Untreated negative controls validity:

valid

Positive controls validity:

valid

Additional information on results:

RANGE-FINDING/SCREENING STUDIES: A pre-experiment for toxicity was used to select concentrations for the main experiment

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

ADDITIONAL INFORMATION ON CYTOTOXICITY: A reduction in mitotic index was observed

Remarks on result:

other: a negative result was determined

Summary of results

Dose Group	Concentration [mM]	Relative Mitotic Index [%]	Proliferation Index	Mean % Aberrant Cells		Historical Laboratory Negative Control Range	Precipitation
				incl. Gaps	excl. Gaps
Experiment I without metabolic activation 4 h treatment, 24 h preparation interval
C	0	75	1.68	2.5	0.00	0.0% - 4.0% aberrant cells	-
S	0	100	1.61	0.5	0.5
2	0.50	79	1.56	0.5	0.0		-
3	1.00	81	1.66	1.5	0.5		-
6	1.75	52	1.14	2.5	0.5		-
EMS	900 μg/ml	62	-	13.5	13.0		-
Experiment II without metabolic activation 24 h treatment, 24 h preparation interval
C	0	102	1.66	1.5	0.5	0.0% - 4.0% aberrant cells	-
S	0	100	1.52	1.0	0.5		-
3	0.40*	72	1.66	1.0	0.5		-
4	0.60**	90	1.32	1.5	0.0		-
6	1.00	58	1.44	2.0	1.0		-
EMS	400 μg/ml	43	-	23.5	20.0		-
Experiment I with metabolic activation 4 h treatment, 24 h preparation interval
C	0	129	1.16	3.0	1.0	.0% - 4.0% aberrant cells	-
S	0	100	1.39	3.0	1.5
1	1.00	117	1.23	2.5	1.5		-
3	2.50	88	1.03	2.5	1.5		-
5	7.50	40	1.06	6.8	2.7		-
EMS	5 μg/ml	87	-	14.5	12.5		-
Experiment II with metabolic activation 4 h treatment, 24 h preparation interval
C	0	105	1.38	2.5	1.0	0.0% - 4.0% aberrant cells	-
S	0	100	1.23	1.5	0.5
3	2.00	87	1.27	1.0	0.5		-
6	6.00	67	1.28	1.5	1.0		+
8	8.00	93	1.16	3.0	1.5		+
EMS	5 μg/ml	98	-	11.0	10.0		-

C:       Negative Control (Culture Medium)

S:       Solvent Control (DMSO)

EMS:  Ethylmethanesulfonate

CPA:   Cyclophosphamide

*          The measured concentration was 0.19 mM with regard to the recovery rate of the GC analysis (47.8%)

**        The measured concentration was 0.47 mM with regard to the recovery rate of the GC analysis (77.6%)

Conclusions:

3-(Trimethoxysilyl)propyl-(2E,4E)-hexa-2,4-dienoate has been tested in an in vitro chromosome aberration study conducted in accordance with OECD 473 (1997) and in compliance with GLP. No test substance-related increase in the number of cells with aberrations was observed up to cytotoxic concentrations in either the initial or the independent repeat experiment. Appropriate solvent, negative (treatment medium) and positive controls were included and gave expected results. It is concluded that the test substance is negative for cytogenicity under the conditions of the test.

Reference 3

Endpoint:

in vitro gene mutation study in mammalian cells

Remarks:

Type of genotoxicity: gene mutation

Type of information:

experimental study

Adequacy of study:

key study

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

Qualifier:

according to guideline

Guideline:

EPA OPPTS 870.5300 - In vitro Mammalian Cell Gene Mutation Test

GLP compliance:

yes (incl. QA statement)

Type of assay:

mammalian cell gene mutation assay

Target gene:

Thymidine kinase operon

Species / strain / cell type:

mouse lymphoma L5178Y cells

Metabolic activation:

with and without

Metabolic activation system:

Phenobarbital (80 mg/kg bw) and β-naphthoflavone (100 mg/kg bw) induced rat liver S9

Test concentrations with justification for top dose:

Without metabolic activation: 0.2, 0.5, 1.0, 1.2, 1.7, 2.0, 2.3, 2.5 mM
With metabolic activation: 0.3, 0.6, 1.3, 2.5, 5.0, 8.0, 9.0, 10.0 mM

Vehicle / solvent:

- Vehicle(s)/solvent(s) used: DMSO
- Justification for choice of solvent/vehicle: Solubility study indicated that the test substance was not soluble in RPMI, but was soluble in DMSO. The solvent was compatible with the survival of the cells and S9 activity.

Untreated negative controls:

yes

Remarks:

treatment medium

Negative solvent / vehicle controls:

yes

Remarks:

DMSO

True negative controls:

no

Positive controls:

yes

Positive control substance:

benzo(a)pyrene

ethylmethanesulphonate

methylmethanesulfonate

Details on test system and experimental conditions:

ACTIVATION: Phenobarbital (80 mg/kg bw) and β-naphthoflavone (100 mg/kg bw) induced rat liver S9. S9 mix included MgCl₂, KCl, glucose-6-phosphate and NADP, with S9 to a final protein concentration of 0.75 mg/ml in the cultures.

METHOD OF APPLICATION: in medium

DURATION
- Exposure duration: 4 hours
- Expression time (cells in growth medium): 48 hours
- Selection time (if incubation with a selection agent): 14 days

SELECTION AGENT (mutation assays): TFT

NUMBER OF REPLICATIONS: no replicates

DETERMINATION OF CYTOTOXICITY
- Method: relative total growth

OTHER EXAMINATIONS:
- Other: occurrence of small colonies

Evaluation criteria:

The test item is considered mutagenic if the following criteria are met:
1) The induced mutant frequency meets or exceeds the Global Evaluation Factor of 126 mutants per 10⁶ cells;
2) A dose-dependent increase in mutant frequency is detected.

Combined with a positive effect in the mutant frequency, an increased occurrence of small colonies (≥40% of total colonies) was considered an indication for potential clastogenic effects and/or chromosomal aberrations.

Statistics:

Statistical significance was investigated by use of the non-parametric Mann-Whitney test.

Key result

Species / strain:

mouse lymphoma L5178Y cells

Metabolic activation:

with

Genotoxicity:

positive

Remarks:

The Global Evaluation Factor (GEF) was exceeded by the mutant frequency at some concentrations; a dose-response relationship was observed.

Cytotoxicity / choice of top concentrations:

cytotoxicity

Remarks:

RTG at 10.00 mM: 24.8%

Vehicle controls validity:

valid

Untreated negative controls validity:

valid

Positive controls validity:

valid

Key result

Species / strain:

mouse lymphoma L5178Y cells

Metabolic activation:

without

Genotoxicity:

negative

Cytotoxicity / choice of top concentrations:

cytotoxicity

Remarks:

The RTG was 19.0% at 2.5 mM, the highest concentration evaluated

Vehicle controls validity:

valid

Untreated negative controls validity:

valid

Positive controls validity:

valid

Additional information on results:

TEST-SPECIFIC CONFOUNDING FACTORS

- Precipitation: precipitation was observed but did not interfere with scoring the colonies.

RANGE-FINDING/SCREENING STUDIES: Cytotoxicity was observed in the pre-experiment for toxicity, with and without metabolic activation

COMPARISON WITH HISTORICAL CONTROL DATA:

ADDITIONAL INFORMATION ON CYTOTOXICITY:

 Summary of mutagenicity results

Concentration (mM)	RTG	MF	IMF	GEF exceeded	Statistical significance	Precipitate
Without metabolic activation
0 (negative control)	107.7/94.9	88.6	/	/	/	-
0 (solvent control)	100	88.5	/	/	/	-
0.2	72.3	80.1	-8.4	-	-	-
0.5	87.9	82.8	-5.7	-	-	-
1.0	68.8	90.9	2.4	-	-	-
1.2	68.0	61.9	-26.6	-	-	+
1.7	70.5	80.3	-8.2	-	-	+
2.0	39.4	128.0	39.5	-	-	+
2.3	27.7	99.3	10.7	-	-	+
2.5	19.0	70.8	-17.7	-	-	+
EMS 300 μg/ml	57.9	886.0	797.5	+	+	-
MMS 10 μg/ml	80.3	425.2	336.5	+	+	-
With metabolic activation
0 (negative control, duplicates)	106.1/1.5.1	72.5	/	/	/	-
0 (solvent control, duplicates)	100	91.3	/	/	/	-
0.3	95.7	101.1	9.8	-	-	-
0.6	108.3	80.2	-11.1	-	-	-
1.3	91.8	81.8	-9.5	-	-	-
2.5	77.2	81.5	-9.8	-	-	+
5.0	53.5	178.2	87.0	-	+	+
8.0	35.4	247.2	156.0	+	+	+
9.0	27.8	222.8	131.5	+	+	+
10.0	24.8	231.4	140.1	+	+	+
B[aP] 1.5 μg/ml	62.2	568.0	476.7	+	+	-

RTG: Relative total growth = (relative suspension growth/relative cloning efficiency)/100

MF: mutant frequency

IMF: induced mutant frequency

GEF: Global Evaluation Frequency

EMS: ethylmethanesulphonate

MMS: methylmethanesulfonate

B[aP]: benzo(a)pyrene

Colony sizing results

Without metabolic activation
Test group	Concentration mM	% small colonies
C1	0	7.5
C2	0	5.0
S1	0	15.6
S2	0	1.8
14 (P)	2.0	14.6
15 (P)	2.3	7.8
16	2.5	8.0
MMS	10 μg/ml	46.8
With metabolic activation
Test group	Concentration	% small colonies
C1	0	3.2
C2	0	5.8
S1	0	4.7
S2	0	8.5
10 (P)	8.0	34.7
11 (P)	9.0	40.6
12 (P)	10.0	49.3
B[a]P	1.5 μg/ml	41.1

C: Negative control

S: Solvent control

(P): Precipitation

MMS: methylmethanesulfonate

B[aP]: benzo(a)pyrene

Conclusions:

Interpretation of results (migrated information):
positive with metabolic activation

3-(Trimethoxysilyl)propyl-(2E,4E)-hexa-2,4-dienoate has been tested in a mammalian gene cell mutation assay conducted in accordance with OECD 476 (1997) and in compliance with GLP. A dose-related increase in excess of the Global Evaluation Frequency was observed in mouse lymphoma L5178Y cells in the presence but not in the absence of metabolic activation. An increase in the percentage of small colonies was observed in the presence of metabolic activation. It is concluded that the test substance is mutagenic and clastogenic to mammalian cells in the presence of metabolic activation under the conditions of the test.

Executive summary:

3-(Trimethoxysilyl)propyl-(2E,4E)-hexa-2,4-dienoate was investigated for its ability to induce gene mutations in mammalian cells using mouse lymphoma L5178Y cells. The cells were exposed for four hours in the presence and the absence of metabolic activation; as a positive result was obtained, a repeat experiment was not required. The following concentrations of the test item were prepared and used in the experiments:

Without metabolic activation: 0.2, 0.5, 1.0, 1.2, 1.7, 2.0, 2.3, 2.5 mM

With metabolic activation: 0.3, 0.6, 1.6, 2.5, 5.0, 8.0, 9.0, 10.0 mM

Non-interfering precipitation was observed at concentrations of 1.2 mM and higher (without metabolic activation) and 2.5 mM and higher (without metabolic activation).

Growth inhibition was observed with and without metabolic activation: Relative total growth (RTG) was 19.0 at the highest concentration (2.5 mM) without metabolic activation and 24.8 at the highest concentration (10 mM) with metabolic activation.

A dose-related increase in the mutant frequency was observed in the main experiment with metabolic activation, and an increase in the percentage of small colonies was recorded. These effects were considered to be biologically relevant.

The reference mutagens induced a distinct increase of mutant frequency indicating the validity of the experiments.

In conclusion, it can be stated that during the described mutagenicity test and under the experimental conditions reported, the test item caused gene mutations and an increase in small colonies in mouse lymphoma L51874Y cells. Therefore, the test item is considered to be mutagenic and clastogenic in this mammalian cell gene mutation assay.

Endpoint conclusion

Endpoint conclusion:

adverse effect observed (positive)

Genetic toxicity in vivo

Description of key information

In vivo:
Micronucleus assay oral (gavage) study in rat: negative (OECD 474, 1997) (BioReliance, 2013).

Link to relevant study records

Reference

Reference 1

Endpoint:

in vivo mammalian somatic cell study: cytogenicity / erythrocyte micronucleus

Remarks:

Type of genotoxicity: chromosome aberration

Type of information:

experimental study

Adequacy of study:

key study

Reliability:

1 (reliable without restriction)

Rationale for reliability incl. deficiencies:

guideline study

Qualifier:

according to guideline

Guideline:

OECD Guideline 474 (Mammalian Erythrocyte Micronucleus Test)

Deviations:

no

GLP compliance:

yes

Type of assay:

micronucleus assay

Species:

rat

Strain:

Sprague-Dawley

Sex:

male/female

Details on test animals or test system and environmental conditions:

TEST ANIMALS
- Source: Harlan, Frederick, MD
- Age at study initiation: 7 weeks
- Weight at study initiation: males: 171.3-174.5 g; females: 140.8-143.3 g
- Assigned to test groups randomly: yes
- Fasting period before study: no
- Housing: Micro-Barrier cage
- Diet: ad libitum
- Water: ad libitum
- Acclimation period: 7 days

ENVIRONMENTAL CONDITIONS
- Temperature (°C): 22 ± 1 °C
- Humidity (%): 50 ± 20%
- Air changes (per hr): at least 10
- Photoperiod (hrs dark / hrs light): 12/12

Route of administration:

oral: gavage

Vehicle:

- Vehicle(s)/solvent(s) used: corn oil
- Justification for choice of solvent/vehicle: none given in study report
- Concentration of test material in vehicle: 100, 200 and 400 mg/ml
- Amount of vehicle (if gavage or dermal): 5 ml

Details on exposure:

PREPARATION OF DOSING SOLUTIONS: Dosing solutions were prepared on the day prior to the study. Test material and vehicle where vortexed and stirred until homogenous.

Duration of treatment / exposure:

Twenty four and forty eight hours

Frequency of treatment:

Single dose

Post exposure period:

Twenty four and forty eight hours

Remarks:

Doses / Concentrations:
500, 1000, 2000 mg/kg bw
Basis:
nominal conc.

No. of animals per sex per dose:

Five rats per sex at each dose level (24 h sampling time), five rats per sex at high dose (48 h sampling time).

Control animals:

yes, concurrent vehicle

Positive control(s):

- Positive control substance: cyclophosphamide
- Justification for choice of positive control(s): none given in study report
- Route of administration: oral (gavage)
- Doses / concentrations: 40 mg/kg bw

Tissues and cell types examined:

Bone marrow: polychromatic erythrocytes and normochromatic erythrocytes

Details of tissue and slide preparation:

CRITERIA FOR DOSE SELECTION: based on toxicity information and guideline recommended high dose

TREATMENT AND SAMPLING TIMES ( in addition to information in specific fields): Sampling times: 24 and 48 hours after dosing

DETAILS OF SLIDE PREPARATION: suspensions of bone marrow cells were spread on a clean glass slides and air dried then fixed in methanol. Two slides were prepared from each rat. One set of slides was stained with acridine orange and used in microscopic evaluation. The second set of slides was frozen

METHOD OF ANALYSIS: Bone marrow was evaluated by fluorescent microscopy. The initial scoring was deemed invalid because of out-of-range historical control values for the vehicle. The slides were therefore re-scored and this data was presented in the study report. Cells were scored under high power. At least 2000 polychromatic erythrocytes (PCE) were scored per animal for micronuclei: the number of cells with micronuclei was recorded. In addition, at least 1000 total erythrocytes (PCEs plus normochromatic erythrocytes (NCE)).

Evaluation criteria:

The test substance is considered positive if it induces a significant increase in micronucleated PCE frequency at any dose level or sampling time compared to the concurrent vehicle control. Other criteria may be used in reaching a conclusion including magnitude of the increase, comparison to historical control values, biological significance.

Statistics:

The frequency of micronucleated PCEs and proportion of PCEs to total erythrocytes was determined for each animal and treatment group. Statistical significance, p ≤ 0.05, was determined using Kastenbaum-Bowman tables.

Key result

Sex:

male/female

Genotoxicity:

negative

Toxicity:

no effects

Remarks:

No mortality or clinical signs; no effect on PCE/NCE ratio

Vehicle controls validity:

valid

Negative controls validity:

not applicable

Positive controls validity:

valid

Additional information on results:

RESULTS OF DEFINITIVE STUDY
- Induction of micronuclei (for Micronucleus assay): no induction of micronuclei observed.
- Ratio of PCE/total erythrocytes (for Micronucleus assay): between 0.422 (low dose males) and 0.464 (high dose, 48 h sampling time males).
- Appropriateness of dose levels and route: dose levels and route were appropriate.
- Statistical evaluation: Only the positive control results were statistically significant.

Summary of bone marrow micronucleus assay following single oral administration of test substance

Concentration mg/kg bw	Sex	Time	Number of animals	PCE/Total erythrocytes	Number of mnPCE/1000 PCE	Number of mnPCE/PCE scored
0 (corn oil)	M	24	5	0.479	0.6	6/10000
	F	24	5	0.444	0.8	8/10000
500	M	24	5	0.422	0.4	4/10000
	F	24	5	0.427	0.6	6/10000
1000	M	24	5	0.427	0.4	4/10000
	F	24	5	0.436	0.6	6/10000
2000	M	24	5	0.438	0.5	5/10000
	F	24	5	0.436	0.4	4/10000
Cyclophosphamide (40)	M	24	5	0.337	26.0*	260*/10000
	F	24	5	0.337	23.6*	236*/10000
Corn oil	M	48	5	0.460	0.8	8/10000
	F	48	5	0.457	0.3	3/10000
2000	M	48	5	0.464	0.5	5/10000
	F	48	5	0.436	0.5	5/10000

PCE: polychromatic erythrocytes

mnPCE: micronucleated PCE

* statistically significant increase compared to the vehicle control, p≤ 0.05

Conclusions:

3-(Trimethoxysilyl)propyl-(2E,4E)-hexa-2,4-dienoate has been tested in an in vivo micronucleus assay conducted in accordance with OECD 474 and in compliance with GLP. No evidence for systemic toxicity, toxicity to bone marrow or induction of micronuclei was observed at any test concentration in bone marrow sampled 24 hours and 48 hours following oral administration by gavage of a single dose of test substance. The animals were dosed with 500, 1000 and 2000 mg/kg bw (24 h sampling time) and 2000 mg/kg bw (48 hour sampling time), Appropriate positive and vehicle controls were included and gave expected results. It is concluded that the test substance is negative for the induction of micronuclei under the conditions of the test.

Reference 2

Endpoint:

in vivo mammalian cell study: DNA damage and/or repair

Type of information:

experimental study planned

Study period:

Planned: after approval by ECHA

Justification for type of information:

TESTING PROPOSAL ON VERTEBRATE ANIMALS

NON-CONFIDENTIAL NAME OF SUBSTANCE:
- Name of the substance on which testing is proposed to be carried out: 3-(trimethoxysilyl)propyl-(2E,4E)-hexa-2,4-dienoate


CONSIDERATIONS THAT THE GENERAL ADAPTATION POSSIBILITIES OF ANNEX XI OF THE REACH REGULATION ARE NOT ADEQUATE TO GENERATE THE NECESSARY INFORMATION:
- Available GLP studies in vitro studies in bacterial and mammalian cells; results negative except for in vitro gene mutation with mammalian cells where a positive response exceeding the Global Evaluation Factor was observed in the presence of metabolic activation. Absence of effects in vivo in a micronucleus assay is not sufficient to address the concerns about potential mutagenicity arising from the positive result.
- Available non-GLP studies: none.
- Historical human data: no relevant data available
- (Q)SAR: in silico methods are available which are able to identify potential genotoxic substances based on the presence of alerts, but (Q)SAR cannot be used to follow up a positive in vitro result.
- In vitro methods: the GLP studies mentioned above include a positive mutagenic response in mammalian cells.
- Weight of evidence: there is only one study per endpoint.
- Grouping and read-across: no suitable read-across data are available.
- Substance-tailored exposure driven testing: not applicable.
- Approaches in addition to above: not applicable.
- Other reasons: not applicable.

CONSIDERATIONS THAT THE SPECIFIC ADAPTATION POSSIBILITIES OF ANNEXES VI TO X (AND COLUMN 2 THEREOF) OF THE REACH REGULATION ARE NOT ADEQUATE TO GENERATE THE NECESSARY INFORMATION:
- Column 2 of Annex VIII Section 8.4 states that "Appropriate in vivo mutagenicity studies shall be considered in case of a positive result in any of the genotoxicity studies in Annex VII or VIII." The REACH Guidance on Information requirements, Part R.8a indicates that an in vivo micronucleus assay is not an appropriate study to consider in the case of positive mutagenicity results in vivo.

FURTHER INFORMATION ON TESTING PROPOSAL IN ADDITION TO INFORMATION PROVIDED IN THE MATERIALS AND METHODS SECTION:
- Details on study design / methodology proposed [if relevant]

Qualifier:

according to guideline

Guideline:

OECD Guideline 489 (In vivo Mammalian Alkaline Comet Assay)

Endpoint conclusion

Endpoint conclusion:

no study available (further information necessary)

Additional information

3-(Trimethoxysilyl)propyl-(2E,4E)-hexa-2,4-dienoate has been tested in a bacterial mutagenicity study conducted in accordance with OECD 471 and in compliance with GLP (BSL Bioservice, 2012e). No increase in the number of revertants was observed when tested with and without metabolic activation in Salmonella typhimurium TA 1535, TA 1537, TA 98, TA 100 and E. coli WP2. Solvent controls and reference mutagens produced results within the range of historical controls. It is concluded that the text substance is negative for mutagenicity to bacterial cells under the conditions of the test.

3-(Ttrimethoxysilyl)propyl-(2E,4E)-hexa-2,4-dienoate has been tested in an in vitro chromosome aberration study conducted in accordance with OECD 473 (1997) and in compliance with GLP (BSL Bioservice, 2013b). No test substance-related increase in the number of cells with aberrations was observed up to cytotoxic concentrations in either the initial or the independent repeat experiment. Appropriate solvent, negative (treatment medium) and positive controls were included and gave expected results. It is concluded that the test substance is negative for cytogenicity under the conditions of the test.

3-(Trimethoxysilyl)propyl-(2E,4E)-hexa-2,4-dienoate has been tested in an in vitro mammalian gene cell mutation assay conducted in accordance with OECD 476 (1997) and in compliance with GLP (BSL Bioservice, 2013c). A dose-related increase in excess of the Global Evaluation Frequency was observed in mouse lymphoma L5178Y cells in the presence but not in the absence of metabolic activation. An increase in the percentage of small colonies was observed in the presence of metabolic activation. Solvent controls and reference mutagens produced results within the range of historical controls. It is concluded that the test substance is mutagenic and clastogenic to mammalian cells in the presence of metabolic activation under the conditions of the test.

3-(Trimethoxysilyl)propyl-(2E,4E)-hexa-2,4-dienoate has been tested in an in vivo micronucleus assay conducted in accordance with OECD 474 and in compliance with GLP (BioReliance, 2013). No evidence for systemic toxicity, toxicity to bone marrow or induction of micronuclei was observed at any test concentration in bone marrow sampled 24 hours and 48 hours following oral administration by gavage of a single dose of test substance. The animals were dosed with 500, 1000 and 2000 mg/kg bw (24 h sampling time) and 2000 mg/kg bw (48 hour sampling time). Appropriate positive and vehicle controls were included and gave expected results. It is concluded that the test substance is negative for the induction of micronuclei in vivo under the conditions of the test.

Although there was no evidence for toxicity to bone marrow and therefore for the test substance reaching the target tissue, data are available from an OECD 417 study (Dow Corning Corporation 2014), which demonstrated that the test substance is systemically available subsequent to oral gavage dosing, therefore it is concluded that the test substance is not clastogenic in vivo.

No data are available to investigate in vivo the potential for mutagenicity to mammalian cells observed in vitro, therefore an in vivo comet assay is proposed.

Justification for classification or non-classification

Based on the available in vitro and in vivo genotoxicity data, 3-(trimethoxysilyl)propyl-(2E,4E)-hexa-2,4 -dienoate does not require classification for mutagenicity according to Regulation (EC) No 1272/2008, however further information on mutagenicity is needed.