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Diss Factsheets

Toxicological information

Skin sensitisation

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Administrative data

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

Data source

Reference
Reference Type:
study report
Title:
Unnamed
Year:
1995

Materials and methods

Test guideline
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.

Test material

Constituent 1
Chemical structure
Reference substance name:
Trimethoxysilane
EC Number:
219-637-2
EC Name:
Trimethoxysilane
Cas Number:
2487-90-3
Molecular formula:
C3H10O3Si
IUPAC Name:
Trimethoxysilane

In vivo test system

Test animals

Species:
guinea pig
Strain:
not specified
Sex:
male/female
Details on test animals and environmental conditions:
No data in IUCLID summary.

Study design: in vivo (non-LLNA)

Induction
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
Challenge
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)

Results and discussion

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.

In vivo (non-LLNA)

Resultsopen allclose all
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

Any other information on results incl. tables

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.

Applicant's summary and conclusion

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.