[3-(2,3-epoxypropoxy)propyl]triethoxysilane

Endpoint summary

Key value for chemical safety assessment

Genetic toxicity in vitro

Description of key information

In a Bacterial Reverse Mutation Assay/Ames test, Gene Mutation Assay, conducted according to OECD Test Guideline 471 and in compliance with GLP, a substantial dose-related increase in the number of revertant colonies was observed in the base pair exchange specific strains TA 1535 and TA 100. The effect was more marked in the presence of metabolic activation, however, was also observed in the absence of metabolic activation. It is concluded that the test substance is positive for mutagenicity to bacteria under the conditions of the test (Cytotest Cell Research, 2001).

In an in vitro micronucleus study, conducted according to OECD Test Guideline 487, no evidence of test-substance induced micronucleus formation was observed in HepG2 cells in either the presence or the absence of metabolic activation. Consequently, it was concluded that the test substance in negative for cytogenicity under the conditions of the test (Lionti et al., 2014).

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:

April 25 2001 - May 11 2001

Reliability:

1 (reliable without restriction)

Rationale for reliability incl. deficiencies:

other: The study was conducted according to the appropriate OECD test guideline, and in compliance with GLP.

Qualifier:

according to guideline

Guideline:

OECD Guideline 471 (Bacterial Reverse Mutation Assay)

Version / remarks:

1997

Deviations:

no

Qualifier:

according to guideline

Guideline:

other: Commission Directive 2000/32/EC L1362000

Qualifier:

according to guideline

Guideline:

other: EPA Code of Federal Regulations 40 Part F

GLP compliance:

yes (incl. QA statement)

Type of assay:

bacterial reverse mutation assay

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:

Phenobarbital and beta-naphthoflavone induced rat liver S9

Test concentrations with justification for top dose:

33-5000 µg/plate

Vehicle / solvent:

- Vehicle(s)/solvent(s) used: ethanol
- Justification for choice of solvent/vehicle: requested by sponsor

Untreated negative controls:

yes

Remarks:

untreated

Negative solvent / vehicle controls:

yes

True negative controls:

no

Positive controls:

yes

Positive control substance:

sodium azide

Remarks:

TA 1535 and TA 100 without metabolic activation

Untreated negative controls:

yes

Remarks:

untreated

Negative solvent / vehicle controls:

yes

True negative controls:

no

Positive controls:

yes

Positive control substance:

other: 4-nitro-o-phenylene-diamine

Remarks:

TA 98 and TA 1537 without metabolic activation

Untreated negative controls:

yes

Remarks:

untreated

Negative solvent / vehicle controls:

yes

True negative controls:

yes

Positive controls:

yes

Positive control substance:

methylmethanesulfonate

Remarks:

TA 102 without metabolic activation

Untreated negative controls:

yes

Remarks:

untreated

Negative solvent / vehicle controls:

yes

True negative controls:

yes

Positive controls:

yes

Positive control substance:

other: 2-aminoanthracene 10 µg/plate TA 102, 2.5 µg/plate all other strains

Remarks:

with metabolic activation in all strains

Details on test system and experimental conditions:

METHOD OF APPLICATION: in agar (plate incorporation)

DURATION
- Exposure duration: 48 hours

SELECTION AGENT (mutation assays): histidine-deficient agar

NUMBER OF REPLICATIONS: triplicate plates; the pre-experiment was reported as part of the main experiment as no relevant toxic effects were observed, and the substance was tested up to limit concentrations.

DETERMINATION OF CYTOTOXICITY
- Method: other: condition of bacterial lawn; reduction in number of revertants. An initial test for cytotoxicity was performed using S. typhimurium strains TA 98 and TA 100.

OTHER: ACTIVATION:
Phenobarbital and beta-naphthoflavone induced rat liver S9 (30.8 mg/ml protein); S9 mix contained 15% v/v S9 and included glucose-6-phosphate and NADP as co-factors. 0.5 ml S9 mix was added to overlay agar, bacterial suspension and test or control solution giving a final concentration of approximately 3%.

Evaluation criteria:

A substance is considered positive if there is a dose-related reproducible increase in the number of revertants exceeding twice (TA 98, TA 100, TA 102 or three times (TA 1535, TA 1537) the solvent control value in more than one concentration.

Species / strain:

S. typhimurium, other: TA 100 and TA 1535

Metabolic activation:

with and without

Genotoxicity:

positive

Remarks:

effect was greater in the presence of metabolic activation

Cytotoxicity / choice of top concentrations:

no cytotoxicity nor precipitates, but tested up to recommended limit concentrations

Vehicle controls validity:

valid

Untreated negative controls validity:

valid

Positive controls validity:

valid

Species / strain:

S. typhimurium, other: TA 98, TA 102, TA 1537

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:

valid

Positive controls validity:

valid

Additional information on results:

TEST-SPECIFIC CONFOUNDING FACTORS
- Effects of pH: no information
- Effects of osmolality: no information
- Evaporation from medium: no information
- Water solubility: not relevant
- Precipitation: none observed
- Other confounding effects: none

RANGE-FINDING/SCREENING STUDIES: no toxicity was observed in the initial toxicity experiment; the pre-experiment was reported as part of the main experiment as no relevant toxic effects were observed, and the substance was tested up to limit concentrations.

COMPARISON WITH HISTORICAL CONTROL DATA: The revertant colony counts of positive control in strain TA 100 exceeded the historical range. This is not considered to compromise the study as fluctuations in positive response are not uncommon in plasmid carrying strains.

ADDITIONAL INFORMATION ON CYTOTOXICITY: no cytotoxicity was observed.

Plate incorporation assay: revertants per plate (mean of three plates)

Concentration µg/plate	TA 1535		TA 1537		TA 98		TA 100		TA 102
	-MA	+MA	-MA	+MA	-MA	+MA	-MA	+MA	-MA	+MA
Negative control	12	12	11	14	27	34	163	169	206	251
Solvent control	12	15	9	13	27	31	151	174	245	248
Positive control	771	320	47	93	29	32	150	165	1122	856
3	-	-	-	-	29	34	151	168	-	-
10	-	-	-	-	30	32	159	159	-	-
33	13	16	9	14	28	29	155	148	221	282
100	17	25	10	12	26	34	160	171	216	201
333	48	123	10	14	31	32	158	320	211	223
1000	64	265	8	11	29	37	202	488	252	234
2500	143	918	8	14	26	34	272	579	193	221
5000	233	1419	10	13	150	693	1175	991	168	380

Conclusions:

[3-(2,3-Epoxypropoxy)propyl]triethoxysilane has been tested according to OECD 471 and in compliance with GLP conditions using Salmonella typhimurium strains TA 98, TA 100, TA 102, TA 1535 and TA 1537. A substantial dose-related increase in the number of revertant colonies was observed in the base pair exchange specific strains TA 1535 and TA 100. The effect was more marked in the presence of metabolic activation, but was also observed in the absence of metabolic activation. Appropriate positive and solvent and untreated controls were included and gave acceptable results. It is concluded that the test substance is positive for mutagenicity to bacteria under the conditions of the test.

Reference 2

Endpoint:

in vitro cytogenicity / micronucleus study

Remarks:

Type of genotoxicity: chromosome aberration

Type of information:

experimental study

Adequacy of study:

key study

Reliability:

2 (reliable with restrictions)

Rationale for reliability incl. deficiencies:

other: The study was conducted according to an appropriate OECD test guideline. GLP compliance is not claimed in the publication.

Qualifier:

according to guideline

Guideline:

other: OECD 487

GLP compliance:

not specified

Remarks:

GLP compliance is not claimed in the publication.

Type of assay:

in vitro mammalian cell micronucleus test

Species / strain / cell type:

mammalian cell line, other: HepG2 cells

Details on mammalian cell type (if applicable):

- Type and identity of media: Minimal Essential Medium
- Properly maintained: yes
- Periodically checked for Mycoplasma contamination: yes
- Periodically checked for karyotype stability: no data
- Periodically "cleansed" against high spontaneous background: no data

Additional strain / cell type characteristics:

other: human cell line from the European Collection of Cell Culture, UK.

Metabolic activation:

with and without

Metabolic activation system:

Phenobarbital/beta-naphthoflavone induced rat liver S9

Test concentrations with justification for top dose:

with metabolic activation: 0.03, 0.06, 0.125, 0.25, 0.5 µg/ml; without metabolic activation: 0.03, 0.06, 0.125, 0.25 µg/ml

Vehicle / solvent:

- Vehicle(s)/solvent(s) used: DMSO

Untreated negative controls:

no

Negative solvent / vehicle controls:

yes

Remarks:

DMSO

True negative controls:

no

Positive controls:

yes

Positive control substance:

other: Vinblastine 0.625 ng/ml

Remarks:

without metabolic activation

Untreated negative controls:

no

Negative solvent / vehicle controls:

yes

True negative controls:

no

Positive controls:

yes

Positive control substance:

cyclophosphamide

Remarks:

10 µg with metabolic activation

Details on test system and experimental conditions:

METHOD OF APPLICATION: in medium

ACTIVATION: Phenobarbital/beta-naphthoflavone induced rat liver S9. S9 mix: final concentration in medium 2% S9; co-factors 5mM glucose-6-phosphate, 0.3 mM NADP, 1.5 mM KCl.

DURATION
- Exposure duration: 3 h with metabolic activation, 24 h without metabolic activation
- Expression time (cells in growth medium): 44 h in medium containing cytochalasin (4 µg/ml). 1 h before harvest cells were washed and re-fed MEM

SPINDLE INHIBITOR (cytogenetic assays): cytochalasin

NUMBER OF REPLICATIONS: duplicate treatments

NUMBER OF CELLS EVALUATED: Micronucleus frequency determined in at least 2000 cells (at least 1000 from each culture). Micronuclei criteria: diameter < one third of main nucleus; clearly distinguishable from main nucleus and staining identical to main nucleus.

DETERMINATION OF CYTOTOXICITY
- Method: other: cytokinesis-block proliferation index (CBPI). CBPI =[(the number of cells with 1 nucleus x 1)+(the number of cells with greater than 2 nuclei x 3)]/total number of cells scored

Evaluation criteria:

According to OECD487

Statistics:

One-way ANOVA followed by Student-Newman-Keuls test, and the differences were considered significant for p less than 0.05.

Species / strain:

mammalian cell line, other: HepG2 cells

Metabolic activation:

with and without

Genotoxicity:

negative

Cytotoxicity / choice of top concentrations:

cytotoxicity

Remarks:

50 % cytotoxicity at highest concentration in absence of metabolic activation

Vehicle controls validity:

valid

Untreated negative controls validity:

not applicable

Positive controls validity:

valid

The results in the paper are presented in the form of bar charts. The numbers in the table below have been estimated from the charts.

Table 1 Results of micronucleus assay for GPTES 

Concentration	MN/1000 BNC		Cytotoxicity (%)
	-MA	+MA	-MA	+MA
Solvent control	12	10	0	0
0.03	13	13	-6	0
0.06	11	13	-10	0
0.125	14	14	-3	0
0.25	12	12	50	2%
0.5	NT	11	NT	25%
Positive control	55	33	4	0

NT not tested

MN micronuclei

BNC binucleated cells

Conclusions:

[3-(2,3-Epoxypropoxy)propyl]triethoxysilane has been tested for ability to induce formation of micronuclei in a study conducted according to OECD 487. No evidence of test-substance induced micronucleus formation was observed in HepG2 cells in either the presence or the absence of metabolic activation. Appropriate positive and solvent controls were included and gave expected results. It is concluded that the test substance in negative for cytogenicity under the conditions of the test.

Endpoint conclusion

Endpoint conclusion:

adverse effect observed (positive)

Genetic toxicity in vivo

Description of key information

In the in vivo micronucleus study, conducted according to OECD TG 474 and in compliance with GLP, no induction of micronucleated polychromatic erythrocytes occurred. There was evidence for exposure of the target tissue in the reported cytotoxicity to bone marrow where a statistically significant increase in the ratio of PCEs to total erythrocytes (EC) was observed. However, this increase was not dose-related. Therefore, it was concluded that the test substance was negative under the conditions of the test (BioReliance Corporation, 2015).

Link to relevant study records

Reference

Endpoint:

in vivo mammalian somatic cell study: cytogenicity / erythrocyte micronucleus

Type of information:

experimental study

Adequacy of study:

key study

Study period:

13th of January 2015 to 16th of March 2015

Reliability:

1 (reliable without restriction)

Rationale for reliability incl. deficiencies:

guideline study

Qualifier:

according to guideline

Guideline:

OECD Guideline 474 (Mammalian Erythrocyte Micronucleus Test)

Version / remarks:

Adopted 26th of Sep 2014

Deviations:

yes

Remarks:

Use of peanut oil that was not anhydrous

GLP compliance:

yes (incl. QA statement)

Type of assay:

mammalian erythrocyte micronucleus test

Species:

mouse

Strain:

CD-1

Details on species / strain selection:

Hsd:ICR (CD-1)

Sex:

male

Details on test animals or test system and environmental conditions:

TEST ANIMALS
- Source: Harlan, Frederick, Maryland, USA
- Age at study initiation: 6 weeks
- Weight at study initiation: 31.5 - 37.0 grams
- Assigned to test groups randomly: yes, a randomised procedure with a weight variation that did not exceed ± 20% of the mean weight.
- Fasting period before study: not specified
- Housing: Up to 5 male animals were housed in Micro-Barrier cage.
- Diet: Harlan 2018C Certified Global Rodent Diet, ad libitum.
- Water: tap water, ad libitum.
- Acclimation period: 6 days

ENVIRONMENTAL CONDITIONS
- Temperature (°C): 22 ± 3°C (72 ± 3°F)
- Humidity (%): 50 ± 20%
- Air changes (per hr): ⩾10 x / hour
- Photoperiod (hrs dark / hrs light): 12 hours light / 12 hours dark

IN-LIFE DATES: From: January 2015 To: 16th of March 2015

Route of administration:

oral: gavage

Vehicle:

- Vehicle(s)/solvent(s) used: Peanut oil
- Justification for choice of solvent/vehicle: The vehicle was selected in consultation with the sponsor based on the test item’s characteristics.
- Concentration of test material in vehicle: 20 mL/kg
- Amount of vehicle: 20 mL/kg for the test and vehicle control and 10 mL/kg for the positive control cyclophosphamide.
- Type and concentration of dispersant aid: N/a
- Lot/batch no.: MKBN5294V
- Purity: not specified

Duration of treatment / exposure:

24 and 48 hours

Frequency of treatment:

Single administration

Post exposure period:

N/a

Dose / conc.:

0 mg/kg bw/day

Remarks:

Control

Dose / conc.:

500 mg/kg bw/day

Dose / conc.:

1 000 mg/kg bw/day

Dose / conc.:

2 000 mg/kg bw/day

No. of animals per sex per dose:

5 males for each treatment group and 5 additional males for the control and positive control, respectively.

Control animals:

yes

yes, concurrent vehicle

Positive control(s):

- Positive control: Cyclophosphamide monohydrate
- Justification for choice of positive control(s): The standard OECD test guideline requires a positive control.
- Route of administration: oral gavage
- Doses / concentrations: 50 mg/kg bw/day

Tissues and cell types examined:

Bone marrow was collected from all treatment groups. Polychromatic erythrocytes (PCEs) and normochromatic erythrocytes (NCEs) were examined for micronuclei.

Details of tissue and slide preparation:

CRITERIA FOR DOSE SELECTION: The doses were based on the results of a previous dose range finding study. The highest dose level was selected with the aim of inducing toxic effects, however, not death or severe suffering. The dose levels tested were 500, 1000 or 2000 mg/kg bw/day. Clinical signs including piloerection was observed at the highest tested dose, however, there were no other toxicological relevant observations. Consequently, the maximum tolerated dose for the definite study was set to 2000 mg/kg bw/day which is also the highest dose that the guideline recommends for this type of assay.

TREATMENT AND SAMPLING TIMES (in addition to information in specific fields): no further information available.

DETAILS OF SLIDE PREPARATION: Following euthanasia, approximately 24 or 48 hours after the final dose, the femurs were exposed (cut just above the knee) and the bone marrow was aspirated into a syringe containing foetal bovine serum. The bone marrow was centrifuged and the supernatant drawn off. The cell pellet was re-suspended and a small drop of the bone marrow suspension was spread onto a clean glass slide (at least 4 slides per mouse). The slides were air-dried, fixed in methanol and stained with acridine orange, the latter was done for one of two sets of slides to enable a set of backup. Slides were thereafter randomly coded.

METHOD OF ANALYSIS: Bone marrow cells were evaluated utilising a fluorescent microscope. At least 4000 polychromatic erythrocytes were scored for micronuclei per animal. To determine the proportion of PCEs as an index of bone marrow cytotoxicity, at least 500 erythrocytes (PCEs and NCEs) were scored per animal.

Evaluation criteria:

To be considered as inducing a positive response, at least one of the test substance doses would exhibit a statistical significant, dose related increase compared to the concurrent negative control as well as with results of the group mean or of the individual animals in at least one group being outside the 95% control limit of the historical negative control data.

Statistics:

Statistical analysis including mean and standard deviation, was performed on the micronucleus frequency and PCE, using the animal as the unit. Moreover, parametric or non-parametric statistical methods were used depending on the variation between groups. Levene’s test was used for determining the group variances for micronucleus frequency for the vehicle and test substance groups. This variation was found to not be significant why a parametric one-way ANOVA was performed followed by a Dunnett post-hoc analysis to compare each dose group to the concurrent vehicle control.
To assess dose responsiveness in the treated groups, a linear regression analysis was conducted. Additionally, a pair-wise comparison (Studen't T-test) was used to compare the positive control group to the concurrent vehicle control group.

Key result

Sex:

male

Genotoxicity:

negative

Remarks:

There was evidence for exposure of the target tissue in the reported cytotoxicity to bone marrow, where a statistically significant increase in the ratio of PCEs to total erythrocytes (EC) was observed. However, this increase was not dose-related.

Toxicity:

no effects

Vehicle controls validity:

valid

Negative controls validity:

valid

Positive controls validity:

valid

Additional information on results:

RESULTS OF RANGE-FINDING STUDY
- Dose range: 500, 1000 or 2000 mg/kg bw/day
- Solubility: not specified
- Clinical signs of toxicity in test animals: Clinical signs included piloerection occurring in the 2000 mg/kg bw/day dose group for both males and females.
- Evidence of cytotoxicity in tissue analysed: Not specified
- Rationale for exposure: The guideline recommends the highest dose do not exceed 2000 mg/kg bw/day.
- Harvest times: not specified
- High dose with and without activation: N/a

RESULTS OF DEFINITIVE STUDY
- Induction of micronuclei: No statistically significant in the incidence of micronucleated polychromatic erythrocytes (MnPCEs) in the test substance-treated groups was observed relative to the negative control group (p<0.05, One-Way ANOVA).
- Ratio of PCE/NCE: There was evidence for exposure of the target tissue in the reported cytotoxicity to bone marrow, where a statistically significant increase in the ratio of PCEs to total erythrocytes (EC) was observed. However, this increase was not dose-related.
- Appropriateness of dose levels and route: The dose levels were based on the dose range finder study which was performed prior to the definitive study. The recommended route in OECD test guideline (474) is oral gavage.
- Statistical evaluation: A statistically significant increase in the incidence of MnCPEs was observed for the positive control. All other criteria for a valid study were also met.

Table 1: Summary of Bone Marrow Micronucleus Analysis

Treatment (20 mL/kg)	Sex	Time (h)	No of Animals	PCE% (Mean ± SD	Change from Control (%)	MnPCE% (Mean ± SD)		Number of MnPCE/PCE Scored
Peanut oil	M	24	5	42.5 ± 1.0	-	0.01 ± 0.01		1/20 000
500 mg/kg bw/day	M	24	5	45.8 ± 0.7	8	0.02 ± 0.02		3/20 000
1000 mg/kg bw/day	M	24	5	44.5 ± 0.7	5	0.01 ± 0.01		1/20 000
2000 mg/kg bw/day	M	24	5	45.5 ± 0.9	7	0.00 ± 0.00		0/20 000
Cyclophosphamide 50 mg/k	M	24	5	50.6 ± 2.0	19	1.84 ± 0.08	**	367/20 000
Peanut oil	M	24	5	42.3 ± 0.6	-	0.01 ± 0.01		2/20 000
2000 mg/kg	M	24	5	46.0 ± 0.7	9	0.03 ± 0.03		6/20 000

* p<0.05 or ** p<0.01, One-Way ANOVA with Post-Hoc analysis or T-Test

PCE – polychromatic erythrocytes; MnPCE – micronucleated polychromatic erythrocytes

Conclusions:

In an in vivo micronucleus study with the test substance [3-(2,3-epoxypropoxy)propyl]triethoxysilane, conducted according to OECD TG 474 and in compliance with GLP, no induction of micronucleated polychromatic erythrocytes occurred. There was evidence for exposure of the target tissue in the reported cytotoxicity to bone marrow where a statistically significant increase in the ratio of PCEs to total erythrocytes (EC) was observed. However, this increase was not dose-related. The positive control provided expected results. It is concluded that the test substance is negative under the conditions of the test.

Endpoint conclusion

Endpoint conclusion:

no study available (further information necessary)

Additional information

Information is available from three bacterial mutagenicity studies on [3-(2,3-epoxypropoxy)propyl]triethoxysilane; the results of these studies were in agreement and the more reliable and more recent was selected as key.

Data are also available from an in vitro micronucleus study on [3-(2,3-epoxypropoxy)propyl]triethoxysilane conducted according to OECD 487 and an in vivo micronucleus assay conducted according to OECD 474.

[3-(2,3-epoxypropoxy)propyl]triethoxysilane has been tested according to OECD test guideline 471 and in compliance with GLP using Salmonella typhimurium strains TA 98, TA 100, TA 102, TA 1535 and TA 1537 (Cytotest Cell Research, 2001). A substantial dose-related increase in the number of revertant colonies was observed in the base pair exchange specific strains TA 1535 and TA 100. The effect was more marked in the presence of metabolic activation, but was also observed in the absence of metabolic activation. Appropriate positive and solvent and untreated controls were included and gave acceptable results. It is concluded that the test substance is positive for mutagenicity to bacteria under the conditions of the test.

An additional supporting study is available in which [3-(2,3-epoxypropoxy)propyl]triethoxysilane has been tested according to OECD test guideline 471 and in compliance with GLP in Salmonella typhimurium strains TA 98, TA 100, TA 1535 and TA 1537 (Cytotest Cell Research, 1995). A dose-related increase in the number of revertants was observed in Salmonella typhimurium strains TA 100 and TA 1535 with and without metabolic activation in both the initial and the repeat assays. Appropriate solvent and positive controls were included and gave expected results. It was concluded that the test substance induced gene mutations by base pair changes in the genome of these strains. The test substance is considered to be mutagenic in Salmonella typhimurium under the conditions of the assay.

In a published bacterial mutagenicity study (Lionti et al., 2014), [3-(2,3-epoxypropoxy)propyl]triethoxysilane was tested in study conducted according to OECD test guideline 471, up to limit concentrations. No data is available on GLP compliance. The substance induced a concentration-related increase in the number of revertants in Salmonella typhimurium strains TA 100 and TA 1535 in the presence and absence of metabolic activation. An increase in the number of revertants in the presence but not the absence of metabolic activation was observed in E. coli WP2 uvr A pKM 101. No indication of mutagenicity was observed with Salmonella typhimurium strains TA 98 and TA 1537. Appropriate positive and solvent controls were included and gave expected results. It is concluded that the test substance is positive for mutagenicity to bacteria under the conditions of the test.

[3-(2,3 -Epoxypropoxy)propyl]triethoxysilane has been tested for ability to induce formation of micronuclei in a study conducted according to OECD 487 (Lionti et al., 2014). No data is available on GLP compliance. No evidence of test-substance induced micronucleus formation was observed in HepG2 cells in either the presence or the absence of metabolic activation. Appropriate positive and solvent controls were included and gave expected results. It is concluded that the test substance in negative for cytogenicity under the conditions of the test.

In an in vivo micronucleus study with the test substance [3-(2,3-epoxypropoxy)propyl]triethoxysilane, conducted according to OECD test guideline 474 and in compliance with GLP, no induction of micronucleated polychromatic erythrocytes occurred in male mice administered a single dose by oral gavage. The dose concentrations were 0, 500, 1000 or 2000 mg/kg bw/day which were selected after a dose range finding study had been conducted. No mortality was observed in the dose range finding study, however, at the highest dose tested (2000 mg/kg bw/day), clinical signs including piloerection occurred in both males and females.

In the definitive study, no statistically significant increase in the incidence of micronucleated polychromatic erythrocytes (MnPCEs) was observed in the test substance-treated groups relative to the negative control group (p < 0.05, One-Way ANOVA). There was evidence for exposure of the target tissue in the reported cytotoxicity to bone marrow where a statistically significant increase in the ratio of PCEs to total erythrocytes (EC) was observed. However, this increase was not dose-related. A statistically significant increase in the incidence of MnCPEs was observed for the positive control. All other criteria for a valid study were met. It was concluded that the test substance was negative under the conditions of the test (BioReliance Corporation, 2015).

The in vivo micronucleus assay is not an appropriate test for follow up of positive bacterial mutagenicity results, therefore an in vivo comet assay is proposed.

Justification for classification or non-classification

Further information is required before a conclusion can be reached on classification of [3-(2,3-epoxypropoxy)propyl]triethoxysilane for germ cell mutagenicity according to Regulation (EC) No 1272/2008.