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Description of key information

The key study for skin sensitisation found that the registered substance, 2,4,6,8-tetramethyl-2,4,6,8-tetravinylcyclotetrasiloxane Vi4-D4, was not sensitising to guinea pig skin (Dow Corning Corporation, 1987). The study was conducted according to an appropriate protocol and in compliance with GLP.

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:
1987
Reliability:
1 (reliable without restriction)
Rationale for reliability incl. deficiencies:
guideline study
Qualifier:
according to guideline
Guideline:
other: Skin sensitization, ASTM F-2147-01, HIMA document No. 10, Vol. 3, August 1981 and literature references
GLP compliance:
yes (incl. QA statement)
Type of study:
split adjuvant test
Justification for non-LLNA method:
An LLNA study was not performed because there is an existing reliable study for skin sensitisation using the Split adjuvant test method. Furthermore, the LLNA test method is not considered to be suitable for substances that contain silicon. Please refer to the attached document for further details.
Species:
guinea pig
Strain:
Hartley
Sex:
male
Details on test animals and environmental conditions:
TEST ANIMALS

- Age at study initiation: 4 weeks
Route:
other: topical
Vehicle:
other: Dow Corning 200 fluid
Concentration / amount:
0.2 ml of 50% dilution in Dow Corning 200 fluid (vehicle), 10 cst for induction
0.1 ml of 15% dilution in Dow Corning 200 fluid (vehicle), 10 cst for challenge
No.:
#1
Route:
other: topical
Vehicle:
other: Dow Corning 200 fluid
Concentration / amount:
0.2 ml of 50% dilution in Dow Corning 200 fluid (vehicle), 10 cst for induction
0.1 ml of 15% dilution in Dow Corning 200 fluid (vehicle), 10 cst for challenge
No. of animals per dose:
10 animals in vehicle (dow Corning 200 fluid, 10 cst)
20 animals in treatment group
Details on study design:
Four induction doses were applied over ten days to the same depilated site on guinea pigs, followed by occlusive patching for 48 hours. At the time of the third application , 0.2 ml of Freunds's Complete Adjuvant was injected to the induction test site. After a ten day rest period, the animals were challenged at a previously unexposed site and occlusive test patch system was held in contact with the skin for 24 hours.
Challenge controls:
At the challenge no skin reaction were observed in the control animals after treatment with test substance diluted to 15%.
Positive control substance(s):
yes
Remarks:
provided by personal communication by Dow Corning Corporation: 0.1% 1-chloro-2,4-dinitrobenzene in acetone
Key result
Reading:
1st reading
Hours after challenge:
24
Group:
test chemical
Dose level:
15% dilution in vehicle
No. with + reactions:
0
Total no. in group:
20
Remarks on result:
no indication of skin sensitisation
Key result
Reading:
2nd reading
Hours after challenge:
48
Group:
test chemical
Dose level:
15% dilution in vehicle
No. with + reactions:
0
Total no. in group:
20
Remarks on result:
no indication of skin sensitisation
Key result
Reading:
1st reading
Hours after challenge:
24
Group:
negative control
Dose level:
15% dilution in vehicle
No. with + reactions:
0
Total no. in group:
10
Remarks on result:
no indication of skin sensitisation
Key result
Reading:
2nd reading
Hours after challenge:
48
Group:
negative control
Dose level:
15% dilution in vehicle
No. with + reactions:
0
Total no. in group:
10
Remarks on result:
no indication of skin sensitisation
Reading:
1st reading
Group:
positive control
Dose level:
0.1% 1-chloro-2,4-dinitrobenzene in acetone
Remarks on result:
other: Results not given

Reading: rechallenge

Hours after challenge: 24.0

Group: test group

Dose level: 15% dilution in vehicle

No with. + reactions: 0.0

Total no. in groups: 20.0

Clinical observations:

Reading: rechallenge

Hours after challenge: 24.0

Group: negative control

Dose level: 15% dilution in vehicle

No with. + reactions: 0.0

Total no. in groups: 10.0

Clinical observations:

Interpretation of results:
GHS criteria not met
Conclusions:
The test material was found not sensitising in albino guinea pigs when tested under the conditions of the Split Adjuvant assay.
Executive summary:

No evidence of skin irritation or skin sensitization was observed in any of the animls following challenge phase. No skin reactions were present in the control group after treatment with vehicle. In the test group after the 4th induction 80% of animals elicited a response of 1 (very slight erythema) or greater (slight to moderate erythema) with mean erythema score of 1.40. At the challenge no skin reactions were observed in either the control or test animals after treatment with test substance diluted to 15%.

Endpoint conclusion
Endpoint conclusion:
no adverse effect observed (not sensitising)
Additional information:

In the key skin sensitisation study for Vi4-D4, conducted according to a protocol (Skin sensitization, ASTM F-2147-01, HIMA document No. 10, Vol. 3) similar to OECD Test Guideline 406 and in compliance with GLP, the substance was found not sensitising in albino guinea pigs when tested under the conditions of the Split Adjuvant assay (Dow Corning Corporation, 1987). No evidence of skin irritation or skin sensitization was observed in any of the animals following challenge phase. No skin reactions were present in the control group after treatment with vehicle. In the test group after the 4th induction 80% of animals elicited a response of 1 (very slight erythema) or greater (slight to moderate erythema) with mean erythema score of 1.40. At the challenge no skin reactions were observed in either the control or test animals after treatment with test substance diluted to 15%.

IMPURITY PROFILE

The registration substance has an average purity of >70% Vi4-D4, with <20% 2,4,6,8,10-pentamethyl-2,4,6,8,10-pentavinylcyclopentasiloxane Vi5-D5 (CAS 17704-22-2; Impurity 1) and <10% 2,4,6-trimethyl-2,4,6-trivinylcyclotrisiloxane Vi3-D3 (CAS 3901-77-7; Impurity 2) present as impurities. After due consideration of the properties, the presence of these impurities is not expected to affect the overall hazard profile of the substance. Read-across studies are in place as supporting studies, to consider the properties of the impurities. Data for Vi5-D5 are read-across from D5 (CAS 541-02-6), data for Vi3-D3 are read-across from D3 (CAS 541-05-9).

Read across from D5 (CAS 541-02-6) [SOURCE SUBSTANCE FOR IMPURITY 1]

For D5, the key skin sensitisation study (BSL Bioservice, 2005), conducted according to a guideline comparable to OECD Test Guideline 429 and in compliance with GLP, concluded the test material to be not sensitising to skin.

Read across from D3 (CAS 541-05-9) [SOURCE SUBSTANCE FOR IMPURITY 2]

For D3, the key skin sensitisation study (Harlan, 2010), conducted according to a guideline comparable to OECD Test Guideline 406 and in compliance with GLP, concluded the test material to be not sensitising to skin.


Respiratory sensitisation

Endpoint conclusion
Endpoint conclusion:
no study available

Justification for classification or non-classification

Based on the available test data, 2,4,6,8-tetramethyl-2,4,6,8-tetravinylcyclotetrasiloxane is not classified as a skin sensitiser according to Regulation (EC) No 1272/2008.

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