Trimethoxysilane

Endpoint summary

Description of key information

In a skin sensitisation study (reliability score 1) conducted according to OECD Test Guideline 406 and in compliance with GLP, trimethoxysilane was not sensitising to the skin of guinea-pigs (DCC, 1995)

Key value for chemical safety assessment

Skin sensitisation

Link to relevant study records

Reference

Endpoint:

skin sensitisation: in vivo (non-LLNA)

Type of information:

experimental study

Adequacy of study:

key study

Study period:

No data

Reliability:

1 (reliable without restriction)

Rationale for reliability incl. deficiencies:

guideline study

Qualifier:

according to guideline

Guideline:

OECD Guideline 406 (Skin Sensitisation)

GLP compliance:

yes

Type of study:

guinea pig maximisation test

Justification for non-LLNA method:

An LLNA study was not performed because there is an existing reliable study for skin sensitisation using the Guinea Pig Maximisation test method.

Species:

guinea pig

Strain:

not specified

Sex:

male/female

Details on test animals and environmental conditions:

No data in IUCLID summary.

Route:

intradermal

Vehicle:

cotton seed oil

Concentration / amount:

1st application: Induction 0.1 ml intracutaneous of 5% test substance in cottonseed oil, 5% test substance in a 1:1 mixture of Freund's Complete Adjuvant (FCA): cottonseed oil and FCA
2nd application: Induction 25 % test substance in occlusive epicutaneous

Day(s)/duration:

Day 0 for intradermal induction and Day 7 for topical induction/48 hours occluded dermal exposure

Adequacy of induction:

highest concentration used causing mild-to-moderate skin irritation and well-tolerated systemically

Route:

epicutaneous, open

Vehicle:

cotton seed oil

Concentration / amount:

3rd application: Challenge 2.5 % open epicutaneous

Day(s)/duration:

Day 21/24 hours of occlusion

Adequacy of challenge:

highest non-irritant concentration

No. of animals per dose:

10/sex/group

Details on study design:

The concentration of test material used for challenge was selected based on the results of range-finding experiment in the Primary Irritation Phase. 
A Test Group of ten male and ten female guinea pigs was dosed with multiple intradermal injections on study day 0 and topical application on study day 7 to attempt to induce a sensitized state for evaluation of delayed contact hypersensitivity. 

1st application: Induction 0.1 ml intracutaneous
2nd application: Induction 25 % occlusive epicutaneous
3rd application: Challenge 2.5 % open epicutaneous

Intradermal induction consisted of injections of 5% trimethoxysilane in cottonseed oil, 5% trimethoxysilane in a 1:1 mixture of Freund's Complete Adjuvant (FCA): cottonseed oil and FCA. Topical induction consisted of a 48-hour occluded dermal exposure to 25% trimethoxysilane. Fourteen days after topical induction, challenge dosing for detection of sensitization was performed.  
For challenge dosing, an essentially non-irritating concentration (2.5%) of the test material was applied topically under occlusion for 24 hours. Vehicle control sites were also dosed at challenge for detection of potential dermal reactions related to the vehicle. A positive control group of five male and five female guinea pigs was included to verify the reliability of the test system.  The positive control group was induced and challenged on a similar regimen as the Test Group using dinitrochlorobenzene (DNCB) in 80% ethanol as the positive control material. Separate sites were dosed with 80% ethanol to detect any reactions related to the vehicle. Reactions to challenge exposures were evaluated at approximately 24 and 48 hours after dosing for all groups. Body weights were recorded prior to study initiation and at termination.

Challenge controls:

A negative control group of five male and five female guinea pigs was dosed with the vehicle during induction and in the same manner as the Test Group at challenge and served as irritation controls.

Positive control substance(s):

yes

Remarks:

dinitrochlorobenzene (DNCB)

Positive control results:

Based on the Sensitization Incidence Index of 100 %, the positive control material, DNCB, was found to be an extreme sensitizing 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 non-sensitizing under the conditions of this study.

Key result

Reading:

1st reading

Hours after challenge:

48

Group:

test chemical

Dose level:

2.5% test substance

No. with + reactions:

0

Total no. in group:

10

Clinical observations:

No clinical signs of toxicity

Remarks on result:

no indication of skin sensitisation

Key result

Reading:

1st reading

Hours after challenge:

48

Group:

negative control

Dose level:

cotton seed oil

No. with + reactions:

0

Total no. in group:

10

Clinical observations:

No clinical signs of toxicity

Remarks on result:

no indication of skin sensitisation

Key result

Reading:

1st reading

Hours after challenge:

48

Group:

positive control

Dose level:

dinitrochlorobenzene

No. with + reactions:

10

Total no. in group:

10

Remarks on result:

positive indication of skin sensitisation

There were no deaths, clinical findings or remarkable body weight changes.

There were no sensitization reactions in the test group following challenge, and the Sensitization Incidence Index was calculated to be 0%. Based on these results, the test material, trimethoxysilane, was found to be a non-sensitizer in albino guinea pigs under the conditions of this study. The negative control and vehicle, cottonseed oil, was also found to be non-sensitizing under the conditions of this study.

Interpretation of results:

GHS criteria not met

Conclusions:

In a skin sensitisation study (reliability score 1) conducted according to OECD Test Guideline 406 and in compliance with GLP, trimethoxysilane was not sensitising to the skin of guinea-pigs.

Endpoint conclusion

Endpoint conclusion:

no adverse effect observed (not sensitising)

Additional information:

In a skin sensitisation study (reliability score 1) conducted according to OECD Test Guideline 406 and in compliance with GLP, a test group  of ten male and ten female guinea pigs was dosed with multiple intradermal injections on study day 0 and topical application on study day 7  to attempt to induce a sensitized state for evaluation of delayed contact hypersensitivity (DCC, 1995).

Intradermal induction consisted of injections of 5% trimethoxysilane in cottonseed oil, 5% trimethoxysilane in a 1:1 mixture  of Freund's Complete Adjuvant (FCA): cottonseed oil and FCA. 

Topical induction consisted of a 48-hour occluded dermal exposure to 25% trimethoxysilane.  Fourteen days after topical induction, challenge dosing for detection of sensitization was performed. For challenge dosing, an essentially non-irritating concentration (2.5%) of the test material was applied topically under occlusion for 24 hours. Vehicle control sites were also dosed at challenge for detection of potential dermal reactions related to the vehicle. A positive control group (using dinitrochlorobenzene) of five male and five female guinea pigs was included to verify the reliability of the test system. There were no deaths, clinical findings or remarkable body weight changes. There were no sensitization reactions in the test group following challenge, and the Sensitisation Incidence Index was calculated to be 0%. Based on these results, trimethoxysilane, was found to be a non-sensitizer in albino guinea-pigs under the conditions of this study. The vehicle, cottonseed oil, was also found to be non-sensitising under the conditions of this study.

Respiratory sensitisation

Endpoint conclusion

Endpoint conclusion:

no study available

Additional information:

There are no data for respiratory sensitisation.

Justification for classification or non-classification

The available data do not suggest that trimethoxysilane should be classified as a skin sensitiser according to Regulation (EC) No. 1272/2008