Registration Dossier

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Description of key information

Key value for chemical safety assessment

Skin sensitisation

Link to relevant study records

Referenceopen allclose all

Endpoint:
skin sensitisation: in vitro
Data waiving:
study scientifically not necessary / other information available
Justification for data waiving:
other:
Endpoint:
skin sensitisation: in vivo (non-LLNA)
Type of information:
experimental study
Adequacy of study:
key study
Study period:
11-02-1994 to 22-03-1995
Reliability:
2 (reliable with restrictions)
Rationale for reliability incl. deficiencies:
other: see 'Remark'
Remarks:
The study was conducted according to an appropriate OECD test guideline, with acceptable restrictions. The restrictions were that a non-irritating challenge concentration as required by the guideline OECD 406 was not identified and no justification for choice of vehicle was given.
Qualifier:
according to
Guideline:
OECD Guideline 406 (Skin Sensitisation)
Deviations:
yes
Remarks:
no justification for choice of vehicle and a non-irritating challenge concentration as required by the guideline was not identified.
GLP compliance:
yes
Type of study:
guinea pig maximisation test
Justification for non-LLNA method:
The current accepted and preferred method for skin sensitisation testing according to the REACH legislation (EC no 1907/2006) and CLP Regulation (EC No 1272/2008) is the murine local lymph node assay (LLNA). A validated test method, OECD TG 429 (OECD 2002) is available for the LLNA. The guideline acknowledges the limits of the LLNA, and states that there are instances where test substance classes or substances containing functional groups shown to act as potential confounders make the use of guinea pig tests more appropriate. It is concluded that the LLNA is not applicable where the properties of the test material cause interference in the accuracy of the LLNA (OECD 2002). The statement in the OECD TG 429 is given with reference to the findings of Basketter et al. (2009a), who demonstrated false positives in silicone based substances which had previously been demonstrated to be non-sensitisers in the guinea pig maximisation test (GPMT). The importance of available evidence from guinea pig results, consideration of chemical reactivity, epidermal bioavailability and clinical and experimental human data are emphasised as central to reaching appropriate regulatory decisions for substances which have been shown to fall outside the specificity of the LLNA (Basketter et al., 2009b). The non-applicability of the LLNA for silicone based substances has also been demonstrated by Petry et al. (2012). The sensitisation potential of polyfunctional silicone materials was tested in a comparative study investigating the GPMT and the LLNA assays, which found the five tested substances to be negative in the GPMT whereas they were concluded to be weak to moderate skin sensitisers in the LLNA (Petry et al., 2012).
Species:
guinea pig
Strain:
Hartley
Sex:
male/female
Details on test animals and environmental conditions:
TEST ANIMALS
- Source: Not reported.
- Age at study initiation: Young adult.
- Weight at study initiation: 300 - 375 g
- Housing: Individual suspended wire-mesh cages.
- Diet: Purina® Certified Rodent Chow® provided ad libitum
- Water: Municipal water were provided ad libitum
- Acclimation period: The animals were acclimated to laboratory conditions for a minimum of seven days prior to initiation of dosing.

ENVIRONMENTAL CONDITIONS
- Temperature : 66-72°F
- Humidity (%): 40-80
- Photoperiod (hrs dark / hrs light): 12/ 12.

IN-LIFE DATES: From: 13-04-1994 To: 14-05-1994.
Route:
intradermal and epicutaneous
Vehicle:
cotton seed oil
Concentration / amount:
Induction: intradermal 5% with and without FCA; epidermal 50%.
Challenge: 5%. Rechallenge 1%.
Route:
epicutaneous, occlusive
Vehicle:
cotton seed oil
Concentration / amount:
Induction: intradermal 5% with and without FCA; epidermal 50%.
Challenge: 5%. Rechallenge 1%.
No. of animals per dose:
10 males and 10 females - Main test group
5 male and 5 females - Positive control group.
5 males and 5 females -Negative control group
4 male and 4 females - Primary Irritation Phase.
Details on study design:
RANGE FINDING TESTS: The 50% concentration of triethoxysilane induced two moderate (grade 2) and two mild (grade 1) reactions at 24 hours and three moderate and one mild reactions at 48 hours. This concentration was selected for topical induction to maximise potential systemic exposure. The 5% concentration of triethoxysilane produced three mild reactions at 24 hours. This was the highest concentration that produced minimal irritation and therefore, appropriate for challenge dosing. The rechallenge dose concentration (1% triethoxysilane) was selected based on the reactions observed among negative control-I animals previously challenged.

MAIN STUDY
A. INDUCTION EXPOSURE
- No. of exposures: 2 (intradermal and epicutaneos, respectively)
- Exposure period: single injection (interdermal) and 48 h (epicutaneous)
- Test groups: Intradermal (3 pairs of injections):
Injection 1: 5% (w/v) solution of triethoxysilane in cotton seed oil
Injection 2: 5% (w/v) solution of triethoxysilane in 1:1 FCA.
Injection 3: a 1:1 mixture (v/v) FCA: cotton seed oil.
Epicutaneous: 50 % (w/v) solution of triethoxysilane in cotton seed oil.
- Control group: Intradermal (3 pairs of injections):The intradermal injections and the topical occlusive application for 48 hours were conducted under the same conditions as in the treated group, cottonseed oil replacing the test substance.
- Site: 2 cm x 4 cm area on the dorsal surface.
- Concentrations: intradermal 5% with and without FCA; epidermal 50%

B. CHALLENGE EXPOSURE
- No. of exposures: 2 (challenge and rechallenge).
- Day(s) of challenge: 21 (challenge) and 28 (rechallenge)
- Exposure period: 24 h and 48 h.
- Test and Control groups: 5% (w/v) concentration of triethoxysilane in cottonseed oil and vehicle (cottonseed oil) - challenge. 1% (w/v) concentration of triethoxysilane in cottonseed oil and vehicle (cottonseed oil) - rechallenge.
- Site: On the anterior flank (challenge) and on the posterior left flank (rechallenge)
- Concentrations: 5% (challenge) and 1% (rechallenge)
- Evaluation (hr after challenge): Application sites were evaluated at approximately 24 and 48 hours after patch removal during the challenge and rechallenge phases.

Challenge controls:
The control group is actually a challenge control.
Positive control substance(s):
yes
Remarks:
Dinitrochlorobenzene (DNCB)
Positive control results:
The sensitisation incidence index was 100% (10/10) for the positive control group. DNCB, was found to be an extremely sensitising agent in the albino guinea pig under the conditions of this study, thereby verifying the reliability of the test system. The positive control vehicle, 80% ethanol, was demonstrated to be essentially non-irritating under the conditions of this study.
Reading:
1st reading
Hours after challenge:
24
Group:
test group
Dose level:
5% test substance
No. with + reactions:
20
Total no. in group:
20
Clinical observations:
6 moderate and 14 mild reactions
Remarks on result:
other: Reading: 1st reading. . Hours after challenge: 24.0. Group: test group. Dose level: 5% test substance. No with. + reactions: 20.0. Total no. in groups: 20.0. Clinical observations: 6 moderate and 14 mild reactions.
Reading:
2nd reading
Hours after challenge:
48
Group:
test group
Dose level:
5% test substance
No. with + reactions:
13
Total no. in group:
20
Clinical observations:
13 mild reactions
Remarks on result:
other: Reading: 2nd reading. . Hours after challenge: 48.0. Group: test group. Dose level: 5% test substance. No with. + reactions: 13.0. Total no. in groups: 20.0. Clinical observations: 13 mild reactions.
Reading:
1st reading
Hours after challenge:
24
Group:
test group
Dose level:
vehicle
No. with + reactions:
19
Total no. in group:
20
Clinical observations:
19 mild reactions
Remarks on result:
other: Reading: 1st reading. . Hours after challenge: 24.0. Group: test group. Dose level: vehicle. No with. + reactions: 19.0. Total no. in groups: 20.0. Clinical observations: 19 mild reactions.
Reading:
2nd reading
Hours after challenge:
48
Group:
test group
Dose level:
vehicle
No. with + reactions:
11
Total no. in group:
20
Clinical observations:
11 mild reactions
Remarks on result:
other: Reading: 2nd reading. . Hours after challenge: 48.0. Group: test group. Dose level: vehicle. No with. + reactions: 11.0. Total no. in groups: 20.0. Clinical observations: 11 mild reactions.
Reading:
1st reading
Hours after challenge:
24
Group:
negative control
Dose level:
5% test substance
No. with + reactions:
10
Total no. in group:
10
Clinical observations:
5 moderate and 5 mild reactions
Remarks on result:
other: Reading: 1st reading. . Hours after challenge: 24.0. Group: negative control. Dose level: 5% test substance. No with. + reactions: 10.0. Total no. in groups: 10.0. Clinical observations: 5 moderate and 5 mild reactions.
Reading:
2nd reading
Hours after challenge:
48
Group:
negative control
Dose level:
5% test substance
No. with + reactions:
8
Total no. in group:
10
Clinical observations:
8 mild reactions
Remarks on result:
other: Reading: 2nd reading. . Hours after challenge: 48.0. Group: negative control. Dose level: 5% test substance. No with. + reactions: 8.0. Total no. in groups: 10.0. Clinical observations: 8 mild reactions.
Reading:
1st reading
Hours after challenge:
24
Group:
negative control
Dose level:
vehicle
No. with + reactions:
8
Total no. in group:
10
Clinical observations:
8 mild reactions
Remarks on result:
other: Reading: 1st reading. . Hours after challenge: 24.0. Group: negative control. Dose level: vehicle. No with. + reactions: 8.0. Total no. in groups: 10.0. Clinical observations: 8 mild reactions .
Reading:
2nd reading
Hours after challenge:
48
Group:
negative control
Dose level:
vehicle
No. with + reactions:
3
Total no. in group:
10
Clinical observations:
3 mild reactions
Remarks on result:
other: Reading: 2nd reading. . Hours after challenge: 48.0. Group: negative control. Dose level: vehicle. No with. + reactions: 3.0. Total no. in groups: 10.0. Clinical observations: 3 mild reactions.
Reading:
rechallenge
Hours after challenge:
24
Group:
test group
Dose level:
1% test substance
No. with + reactions:
20
Total no. in group:
20
Clinical observations:
5 moderate and 15 mild reactions
Remarks on result:
other: Reading: rechallenge. . Hours after challenge: 24.0. Group: test group. Dose level: 1% test substance. No with. + reactions: 20.0. Total no. in groups: 20.0. Clinical observations: 5 moderate and 15 mild reactions .
Reading:
rechallenge
Hours after challenge:
48
Group:
test group
Dose level:
1% test substance
No. with + reactions:
18
Total no. in group:
20
Clinical observations:
2 moderate and 16 mild reactions
Remarks on result:
other: Reading: rechallenge. . Hours after challenge: 48.0. Group: test group. Dose level: 1% test substance. No with. + reactions: 18.0. Total no. in groups: 20.0. Clinical observations: 2 moderate and 16 mild reactions .
Reading:
rechallenge
Hours after challenge:
24
Group:
other: negative control II
Dose level:
1% test substance
No. with + reactions:
9
Total no. in group:
9
Clinical observations:
6 mild and 3 moderate reactions
Remarks on result:
other: Reading: rechallenge. . Hours after challenge: 24.0. Group:
Reading:
rechallenge
Hours after challenge:
48
Group:
other: negative control II
Dose level:
1% test substance
No. with + reactions:
8
Total no. in group:
9
Clinical observations:
8 mild reactions
Remarks on result:
other: Reading: rechallenge. . Hours after challenge: 48.0. Group:

Table 1. Incidence of dermal response – Challenge phase

Group

Material

Interval

Dermal Score

Number of animals

Sensitisation Assessment

0

1

2

3

Test

5% Triethoxysilane in cottonseed oil

24 hrs

0

14

6

0

20

1.3

48 hrs

7

13

0

0

20

0.7

Test

100% cotton seed oil

24 hrs

1

19

0

0

20

1.0

48 hrs

9

11

0

0

20

0.6

Negative Control-I

5% Triethoxysilane in cotton seed oil

24 hrs

0

5

5

0

10

1.5

48 hrs

2

8

0

0

10

0.8

Negative Control-I

100% cotton seed oil

24 hrs

2

8

0

0

10

0.8

48 hrs

7

3

0

0

10

0.3

Positive Control

0.1% DNCB in 80% Ethanol

24 hrs

0

0

7

3

10

2.3

48 hrs

0

0

4

6

10

2.6

Positive Control

80% Ethanol

24 hrs

3

 

7

0

0

10

0.7

48 hrs

9

1

0

0

10

0.1

Table 2. Incidence of dermal response – rechallenge phase.

Group

Material

Interval

Dermal Score

Number of animals

Sensitisation Assessment

0

1

2

3

Test

1% Triethoxysilane in cotton seed oil

24 hrs

0

15

5

0

20

1.3

48 hrs

2

16

2

0

20

1.0

Test

100% cotton seed oil

24 hrs

0

20

0

0

20

1.0

48 hrs

6

14

0

0

20

0.7

Negative Control-II

1% Triethoxysilane in cotton seed oil

24 hrs

0

6

0

0

9

1.3

48 hrs

1

8

0

0

9

0.9

Negative Control-II

100% cotton seed oil

24 hrs

0

9

0

0

9

1.0

48 hrs

2

7

0

0

9

0.8

Challenge phase result:

The 5% concentration of Triethoxysilane induced six moderate and fourteen mild reactions at 24 hours post-challenge in the test group. Thirteen mild reactions were noted for the same animals at 48 hours. Vehicle (cotton seed oil) control sites on the test group animals had nineteen and eleven mild reactions at 24 and 48 hours, respectively.

For the negative control-I group animals, the 5% Triethoxysilane concentration induced five moderate and five mild reactions at 24 hours post-challenge. At 48 hours, eight mild reactions at the test material dosed sites were noted. Vehicle dosed sites had eight and three mild reactions reported at 24 and 48 hours, respectively.

In the positive control group, three severe (grade 3) reactions and seven moderate reactions were observed at 24 hours at the DNCB dosed sites. At 48 hours, six severe, four moderate reactions and five eschar formations were noted. The positive control group guinea pigs had seven and one mild reactions at 24 and 48 hours, respectively, for vehicle (80 % ethanol) treated sites.

Rechallenge results:     

                 

The 1 % concentration of Triethoxysilane induced five moderate and fifteen mild reactions for test group animals at 24 hours. Two moderate and sixteen mild reactions were noted for the same animals at 48 hours. Vehicle (cotton seed oil) control sites for the test group animals had twenty and fourteen mild reactions at 24 and 48 hours, respectively.

The negative control-II group guinea pigs had three moderate and six mild reactions for test material dosed at 24 hours. At 48 hours, eight mild reactions at the test material dosed sites were observed. Vehicle (cotton seed oil) dosed sites had nine and seven mild reactions at 24 and 48 hours, respectively. The sensitisation index was calculated to be 0 % (0/20) for the test group following challenge and rechallenge dosing. The sensitisation index was 100% (10/10) for the positive control.

Interpretation of results:
not sensitising
Remarks:
Migrated information Criteria used for interpretation of results: EU
Conclusions:
In a reliable Guinea pig Maximisation Test conducted to GLP and OECD 406, triethoxysilane was found to be a non-sensitiser
Endpoint:
skin sensitisation: in vivo (non-LLNA)
Type of information:
migrated information: read-across from supporting substance (structural analogue or surrogate)
Adequacy of study:
key study
Study period:
16.09.1991 to 16.06.1992
Reliability:
2 (reliable with restrictions)
Rationale for reliability incl. deficiencies:
other: see 'Remark'
Remarks:
The study was conducted according to a test protocol that is comparable to the appropriate OECD test guideline, and in compliance with GLP and is therefore considered to be reliability 1. Read-across of the study itself is considered to be reliability 2. Further information on read-across is given in the endpoint summary.
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.
Qualifier:
according to
Guideline:
OECD Guideline 406 (Skin Sensitisation)
Deviations:
yes
Remarks:
; no info on when sensitivity test was done - OECD 406 states that should be every 6 months.
GLP compliance:
yes
Type of study:
guinea pig maximisation test
Justification for non-LLNA method:
The current accepted and preferred method for skin sensitisation testing according to the REACH legislation (EC no 1907/2006) and CLP Regulation (EC No 1272/2008) is the murine local lymph node assay (LLNA). A validated test method, OECD TG 429 (OECD 2002) is available for the LLNA. The guideline acknowledges the limits of the LLNA, and states that there are instances where test substance classes or substances containing functional groups shown to act as potential confounders make the use of guinea pig tests more appropriate. It is concluded that the LLNA is not applicable where the properties of the test material cause interference in the accuracy of the LLNA (OECD 2002). The statement in the OECD TG 429 is given with reference to the findings of Basketter et al. (2009a), who demonstrated false positives in silicone based substances which had previously been demonstrated to be non-sensitisers in the guinea pig maximisation test (GPMT). The importance of available evidence from guinea pig results, consideration of chemical reactivity, epidermal bioavailability and clinical and experimental human data are emphasised as central to reaching appropriate regulatory decisions for substances which have been shown to fall outside the specificity of the LLNA (Basketter et al., 2009b). The non-applicability of the LLNA for silicone based substances has also been demonstrated by Petry et al. (2012). The sensitisation potential of polyfunctional silicone materials was tested in a comparative study investigating the GPMT and the LLNA assays, which found the five tested substances to be negative in the GPMT whereas they were concluded to be weak to moderate skin sensitisers in the LLNA (Petry et al., 2012).
Species:
guinea pig
Strain:
Hartley
Sex:
male/female
Details on test animals and environmental conditions:
TEST ANIMALS
- Source: Iffa- Credo (69592 L'Arbresle Cedex - France), Elevage Lebeau (78950 Gambais - France), Interfauna (37600 Loches - France), Charles River France.
- Age at study initiation: 'young' adult
- Weight at study initiation: 300 - 500 g
- Housing: by sex and in groups of five or six (2 for preliminary studies), in polystyrene cages with perforated flooring.
- Diet (e.g. ad libitum): Ad libitum
- Water (e.g. ad libitum): Ad libitum
- Acclimation period: At least one week

ENVIRONMENTAL CONDITIONS
- Temperature (°C): 20 ±3
- Humidity (%): 30-70
- Air changes (per hr): No data
- Photoperiod (hrs dark / hrs light): 12/12

IN-LIFE DATES: From: 16.09.1991 to 16.06.1992
Route:
intradermal and epicutaneous
Vehicle:
other: Sterile Codex liquid paraffin
Concentration / amount:
Induction: 25%
Challenge: 10%
Route:
epicutaneous, occlusive
Vehicle:
other: Sterile Codex liquid paraffin
Concentration / amount:
Induction: 25%
Challenge: 10%
No. of animals per dose:
Preliminary studies (minimum of 3): 2 males, 2 non-pregnant females, per study.
Main study: Control group: 10 males, 10 non-pregnant females.
Treated group: 10 males, 10 non-pregnant females. Two extra guinea pigs (1/sex) treated to allow for any possible non-treatment-related deaths.
Details on study design:
RANGE FINDING TESTS: 0.1 ml intradermal injection of 50, 25 and 10% was administered to the dorsal region in order to determine the concentration that will provoke a weak to moderate irritation and which is not toxic. The skin was evaluated at each concentration at 24 and 48 hours after the injections, according to the scale of Magnusson and Kligman. For the topical application a 48 hour occlusive patch test was performed with 50 and 25%. The aim of the topical applications is to determine the concentration that will provoke a weak to moderate irritation and which is non-toxic. The skin was evaluated at each concentration at 24 and 48 hours after the injections, according to the scale of Magnusson and Kligman.

To determine the challenge concentration a 0.5 ml topical application of the test substance was applied using a 24 hour occlusive patch test in order to determine the maximum non-irritating concentration. The treated skin was evaluated at 24 and 48 hours after removal of the patches according to the above mentioned scale.

MAIN STUDY
A. INDUCTION EXPOSURE
- No. of exposures: Two (one intradermal on Day 1 and one topical on Day 9)
- Exposure period: Topical application was for 48 hours
- Test groups: Intradermal: 3 series of 2 x 0.1 ml injections: 1) Freund's complete adjuvant at 50% (v/v) in an isotonic injectable solution; 2) test substance in a 25% (v/v) solution in Sterile Codex liquid paraffin; 3) mixture 50/50 (v/v): test substance in a 50% (v/v) solution in Sterile Codex liquid paraffin + Freund's complete adjuvant at 50% (v/v) in an isotonic injectable solution, i.e. a final 25% concentration of the test substance.
Topical occlusive: 0.5 ml of the test substance in a 50% (v/v) solution in Sterile Codex liquid paraffin.
- Control group: The intradermal injections and the topical oclusive application for 48 hours were conducted under the same conditions as in the treated group, Sterile Codex liquid paraffin replacing the test substance.
- Site: clipped dorsal shoulder region
- Concentrations: 25% solution (weak to moderate irritation in preliminary study)

B. CHALLENGE EXPOSURE
- No. of exposures: One
- Day(s) of challenge: Following 11 days 'rest period' the challenge phase was initiated on Day 22.
- Exposure period: 24 hours
- Test and control groups: Topical occlusive application for 24 hours was performed in the treated and control group with the test substance in a 10% (v/v) solution in Sterile Codex liquid paraffin and at a rate of 0.5 ml.
- Site: Clipped and shaved flank
- Concentrations: 10% (maximum non-irritating concentration)
- Evaluation (hr after challenge): 24 and 48

OTHER: Histopathological examinations of the skin were performed for three animals of the treated group which showed doubtful macrscopic reactions at 48 hours.
Challenge controls:
Vehicle challenge
Positive control substance(s):
no
Remarks:
Sensitivity test conducted (no date)
Positive control results:
No positive controls. However, it appears that the laboratory had conducted the same protocol with reference substances to show the sensitivity of their methodology.
Reading:
1st reading
Hours after challenge:
24
Group:
negative control
Dose level:
10% TS
No. with + reactions:
0
Total no. in group:
20
Clinical observations:
No erythema or edema in any animal. Mild desquamation at test substance site at 24 and 48 hour readings (observed in more males than females).
Remarks on result:
other: see Remark
Remarks:
Reading: 1st reading. . Hours after challenge: 24.0. Group: negative control. Dose level: 10% TS. No with. + reactions: 0.0. Total no. in groups: 20.0. Clinical observations: No erythema or edema in any animal. Mild desquamation at test substance site at 24 and 48 hour readings (observed in more males than females). .
Reading:
2nd reading
Hours after challenge:
48
Group:
negative control
Dose level:
10 % TS
No. with + reactions:
0
Total no. in group:
20
Clinical observations:
No erythema or edema in any animal. Mild desquamation at test substance site at 24 and 48 hour readings (observed in more males than females).
Remarks on result:
other: see Remark
Remarks:
Reading: 2nd reading. . Hours after challenge: 48.0. Group: negative control. Dose level: 10 % TS. No with. + reactions: 0.0. Total no. in groups: 20.0. Clinical observations: No erythema or edema in any animal. Mild desquamation at test substance site at 24 and 48 hour readings (observed in more males than females). .
Reading:
1st reading
Hours after challenge:
24
Group:
test group
Dose level:
10% TS
No. with + reactions:
0
Total no. in group:
20
Clinical observations:
No erythema and edema in any animal. Desquamation in one animal.
Remarks on result:
other: Reading: 1st reading. . Hours after challenge: 24.0. Group: test group. Dose level: 10% TS. No with. + reactions: 0.0. Total no. in groups: 20.0. Clinical observations: No erythema and edema in any animal. Desquamation in one animal. .
Reading:
2nd reading
Hours after challenge:
48
Group:
test group
Dose level:
10%
No. with + reactions:
0
Total no. in group:
20
Clinical observations:
No erythema/edema in males, Grade 1 erythema/edema in three females. 7/10 males and 4/10 females showed desquamation (including the three with erythema/edema).
Remarks on result:
other: see Remark
Remarks:
Reading: 2nd reading. . Hours after challenge: 48.0. Group: test group. Dose level: 10%. No with. + reactions: 0.0. Total no. in groups: 20.0. Clinical observations: No erythema/edema in males, Grade 1 erythema/edema in three females. 7/10 males and 4/10 females showed desquamation (including the three with erythema/edema). .

Signs of irritation were noted during the induction. The macroscopic and histopathological examinations did not reveal any lesion of delayed hypersensitivity in the 20 treated animals. No noticeable cutaneous abnormality was noted in the 20 guinea pigs examined in the control group.

Interpretation of results:
not sensitising
Remarks:
Migrated information Criteria used for interpretation of results: EU
Conclusions:
In a Guinea pig Maximisation Test conducted to GLP and OECD 406 for the structural analogue substance triethoxy(methyl)silane (CAS: 2031-67-6). was not sensitising to the skin.
Endpoint conclusion
Endpoint conclusion:
no adverse effect observed (not sensitising)
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.Other available data are included as supporting studies.

In a key guinea pig maximisation test conducted in compliance with GLP and according to OECD TG 406, triethoxysilane was found to be a non-sensitiser (DCC 1995f). The sensitisation index was calculated to be 0% for the test group following challenge and rechallenge. However, challenge and re-challenge with the test substance caused the same grade of irritation in both the test group and the control group. A non-irritating challenge concentration as required by the guideline OECD 406 was not identified. Based on the results of the study the authors concluded that triethoxysilane has no sensitising potential, due to the fact that no difference in irritation was observed among the groups.

A group of ten male and female guinea pigs was dosed with multiple intradermal injections on day 0 following a topical application on day 7 in order to investigate sensitisation potential of triethoxysilane. The topical induction consisted of a 48 hour occluded dermal exposure to 50 % triethoxysilane. Fourteen days after topical induction, challenge dosing for detection of sensitisation was performed. For challenge dosing, an essentially non-irritating concentration (5%) of the test material was applied under occlusion for 24 hours. One week after challenge dosing, test groups animals were rechallenged and the initial challenge results were confirmed. The positive control vehicle, 80% ethanol, was demonstrated to be essentially non-irritating under the conditions of this study.

A key skin sensitisation study is also available on the structural analogue substance triethoxy(methyl)silane (CAS: 2031-67-6). Both of these substances hydrolyse to produce structurally similar silanol hydrolysis products, methylsilanetriol and silantriol, and are therefore deemed to be sufficient for read-across. 

In a guinea pig maximisation test conducted in compliance with GLP and according to OECD TG 406, the structural analogue substance triethoxy(methyl)silane was found to be a non-sensitiser. The sensitisation index was calculated to be 0% for the test group following challenge. A group of ten male and ten female guinea pigs was dosed with multiple intradermal injections on day 0 following a topical application on day 7 to induce a possible sensitised state for evaluation for delayed contact hypersensitivity.

The topical induction consisted of a 48 hour occluded dermal exposure to 0.5 ml of the test substance in a 50% (v/v) solution in sterile codex liquid paraffin. Eleven days after topical induction, challenge dosing for detection of sensitisation was performed. For challenge dosing, an essentially non-irritating concentration (10% (v/v)) of the test material was applied under occlusion for 24 hours. The test material vehicle, sterile codex liquid paraffin, was also found to be non-sensitising under the conditions of this study (Hazelton France, 1992). The results of both experiments are in agreement with the lack of skin sensitisation potential of the registered substance.


Respiratory sensitisation

Endpoint conclusion
Endpoint conclusion:
no study available

Justification for classification or non-classification

The available data on skin sensitisation of the registered substance and the structural analogue substance triethoxy(methyl)silane (CAS: 2031 -67 -6) do not meet the criteria for classification according to Regulation 1272/2008 or EU Directive 67/548/EEC, and are therefore conclusive but not sufficient for classification of the registered substance.