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Administrative data

Description of key information

In the key (only) skin sensitisation study conducted according to OECD Test Guideline 406 (non-LLNA, prior to LLNA OECD Test Guideline 429) and in compliance with GLP (Degussa-Huls AG 1993, Buehler test, reliability score 2), tetraethyl orthosilicate (CAS 78-10-4; EC No. 201-083-8) was not sensitising to the skin of guinea pigs. The reliability score 2 reflects a reduced number of guinea pigs (less than the 20 test animals recommended).

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:
1992/11/02 to 1993/01/19
Reliability:
2 (reliable with restrictions)
Rationale for reliability incl. deficiencies:
guideline study with acceptable restrictions
Remarks:
The restriction was a reduced number of test animals.
Qualifier:
according to guideline
Guideline:
OECD Guideline 406 (Skin Sensitisation)
Version / remarks:
Specified as OECD Test Guideline 406, as updated 1987/02. Current version adopted 1992/07/17.
Deviations:
yes
Remarks:
Only 10 test animals; guideline requires 20, and details of the laboratory control not presented in the report.
GLP compliance:
yes
Type of study:
Buehler test
Justification for non-LLNA method:
The available test was conducted in 1993, prior to the availabiliity of a validated test guideline for the LLNA (OECD Test Guideline 429)
Species:
guinea pig
Strain:
Dunkin-Hartley
Remarks:
Pirbright White, [Bor]: DHPW (SPF)
Sex:
female
Details on test animals and environmental conditions:
TEST ANIMALS
- Source: Winkelmann Co., 4799 Borchen
- Age at study initiation: "Young"
- Weight at study initiation: 424±23 g
- Housing: Conventional, maximum of 5 per Macrolon cage Type IV
- Diet (e.g. ad libitum): "Ssniff G 4," ad libitum
- Water (e.g. ad libitum): Municipal water, ad libitum
- Acclimation period: At least five days

ENVIRONMENTAL CONDITIONS
- Temperature (°C): 20±3
- Humidity (%): 30-70
- Air changes (per hr): 15
- Photoperiod (hrs dark / hrs light): 12/12

IN-LIFE DATES: 03.11.1992 to 10.12.1992
Route:
epicutaneous, occlusive
Vehicle:
other: MEH 56 corn oil
Concentration / amount:
100% for first two inductions and 50% for third induction
No.:
#1
Route:
epicutaneous, occlusive
Vehicle:
other: MEH 56 corn oil
Concentration / amount:
50% for challenge
No. of animals per dose:
10F
Details on study design:
RANGE FINDING TESTS: Gauze sponges measuring 2cm x 2cm were each coated with about 0.4 g of tetraethyl orthosilicate in MEH 56 corn oil at concentrations of 2.5, 25, 50 or 100% and applied to the shaved flank area. MEH 56 corn oil as control was applied to the shoulder or thigh. Each gauze was covered with an occlusive dressing and held in place for 6 hours by bandage. After removal of the patch, the remaining substance was removed using corn oil and a cellulose swab. The dermal reaction was evaluated immediately after patch removal and again at 24 and 48 hours.

MAIN STUDY
A. INDUCTION EXPOSURE
- No. of exposures: 3
- Exposure period: 6 hours
- Test groups: 100 % tetraethyl orthosilicate for inductions 1 and 2, and 50% for induction 3.
- Control group: MEH 56 corn oil
- Site: Left flank
- Frequency of applications: Day 0, day 7, day 14
- Evaluation (hours after challenge): 6 and 24, after bandage removal.

B. CHALLENGE EXPOSURE
- No. of exposures: 1
- Day(s) of challenge: Day 28
- Exposure period: 6 hours
- Test groups: tetraethyl orthosilicate
- Control group: MEH 56 corn oil
- Site: Right flank
- Concentrations: 50%
- Evaluation (hours after challenge): 6, 24, 48 and 72 after bandage removal.

C. OTHER EVALUATIONS
- Body weight: Day 0, once a week, and at study end, in tetraethyl orthosilicate and MEH 56 corn oil groups
- Systemic effects: Recorded, in tetraethyl orthosilicate and MEH 56 corn oil groups
Challenge controls:
Negative control was MEH 56 corn oil.
Positive control substance(s):
no
Positive control results:
No positive control.
Key result
Reading:
1st reading
Hours after challenge:
24
Group:
test chemical
Dose level:
50%
No. with + reactions:
0
Total no. in group:
10
Clinical observations:
no test substance-related systemic or body weight effects
Remarks on result:
no indication of skin sensitisation
Remarks:
at 24, 48, or 72 hr
Key result
Reading:
2nd reading
Hours after challenge:
48
Group:
test chemical
Dose level:
50 %
No. with + reactions:
0
Total no. in group:
10
Clinical observations:
no test substance-related systemic or body weight effects
Remarks on result:
no indication of skin sensitisation
Remarks:
at 24, 48, or 72 hr
Key result
Reading:
1st reading
Hours after challenge:
24
Group:
negative control
Dose level:
corn oil
No. with + reactions:
0
Total no. in group:
10
Remarks on result:
no indication of skin sensitisation
Remarks:
at 24, 48, or 72 hr
Key result
Reading:
2nd reading
Hours after challenge:
48
Group:
negative control
Dose level:
corn oil
No. with + reactions:
0
Total no. in group:
10
Remarks on result:
no indication of skin sensitisation
Remarks:
at 24, 48, or 72 hr
Key result
Reading:
1st reading
Hours after challenge:
24
Group:
positive control
Remarks on result:
other: no positive control included
Key result
Reading:
2nd reading
Hours after challenge:
48
Group:
positive control
Remarks on result:
other: no positive control included

There were no test substance-related effects or influence on body weight in either the tetraethyl orthosilicate or MEH corn oil control animals. Very light erythema was observed for tetraethyl orthosilicate in 2 of 10 animals during Induction Phase I (at 24 hours), and in 3 of 10 animals in Induction Phase II (at 24 hours). Two (2) of the 3 animals with erythema in Induction Phase II also had very light edema. There was no skin irritation observed for the tetraethyl orthosilicate in Induction Phase III (at 24 hours) or in the Challenge Phase (at 24, 48 and 72 hours). No skin irritation was observed in the MEH corn oil control animals either during induction (at 24 hours) or challenge (24, 48, and 72 hours).

Interpretation of results:
GHS criteria not met
Conclusions:
In the key skin sensitisation study (Buehler test; reliability score 2) conducted according to OECD Test Guideline 406 (non-LLNA, prior to LLNA OECD Test Guideline 429) and incompliance with GLP, tetraethyl orthosilicate was not sensitising to the skin of guinea pigs.
Endpoint conclusion
Endpoint conclusion:
no adverse effect observed (not sensitising)
Additional information:

In the skin sensitisation study conducted according to OECD Test Guideline 406 (non-LLNA, prior to LLNA OECD Test Guideline 429) and in compliance with GLP (Degussa-Huls AG 1993, reliability score 2), guinea pigs were exposed to tetraethyl orthosilicate over 2 cm by 2 cm of skin for 6 hours, under occlusive conditions, at 100% tetraethyl orthosilicate applied for inductions I and II, and at 50% tetraethyl orthosilicate in corn oil for induction III and at challenge. Ten (10) test animals were used versus the recommended 20; controls (10) as recommended. After challenge, evaluations were performed at bandage removal and at 24, 48, and 72 hours afterwards. There were no test substance-related effects or influence on body weight. Very light erythema was observed for tetraethyl orthosilicate in 2 of 10 animals during induction I (at 24 hours), and in 3 of 10 animals in induction II (at 24 hours). Two (2) of the 3 animals with erythema in induction II also had very light oedema. There was no skin irritation observed for the tetraethyl orthosilicate in induction III (at 24 hours) or at challenge (at 24, 48 and 72 hours). Tetraethyl orthosilicate was not sensitising to the skin of guinea pigs.

Respiratory sensitisation

Endpoint conclusion
Endpoint conclusion:
no study available

Justification for classification or non-classification

Based on the key skin sensitisation study, tetraethyl orthosilicate is not a skin sensitizer and does not require classification for skin or respiratory sensitisation according to Regulation (EC) 1272/2008.