Registration Dossier

Administrative data

Description of key information

There are no skin sensitisation data for the registered substance, 1,1,3,3-tetramethyldisiloxane (CAS 3277-26-7). Therefore data for the structural analogue, hexamethyldisiloxane (HMDS; CAS 107-46-0) have been read across. A human patch test study on the related hexamethyldisiloxane (CAS 107-46-0), reported no evidence of sensitising potential (Dow Corning Corporation, 1992).

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:
02.12.1991 to 10.01.1992
Reliability:
2 (reliable with restrictions)
Rationale for reliability incl. deficiencies:
study well documented, meets generally accepted scientific principles, acceptable for assessment
Principles of method if other than guideline:
Human Patch test to determine whether the test material was capable of sensitising the skin of humans under controlled patch test conditions.
GLP compliance:
not specified
Type of study:
patch test
Justification for non-LLNA method:
An LLNA study was not performed because there is an existing reliable study for skin sensitisation using Human Patch 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:
human
Sex:
male/female
Details on test animals and environmental conditions:
TEST ANIMALS
- Source: Not applicable
- Age at study initiation: 18 to 78 years
- Weight at study initiation: Not applicable
- Housing: Not applicable
- Diet (e.g. ad libitum): Not applicable
- Water (e.g. ad libitum): Not applicable
- Acclimation period: Not applicable


ENVIRONMENTAL CONDITIONS: Not applicable


IN-LIFE DATES: From: 02.12.1991 to 10.01.1992
Route:
epicutaneous, semiocclusive
Vehicle:
unchanged (no vehicle)
Concentration / amount:
Undiluted
Route:
epicutaneous, semiocclusive
Vehicle:
unchanged (no vehicle)
Concentration / amount:
Undiluted
No. of animals per dose:
100
Details on study design:
1st application: Induction undiluted semiocclusive (0.2ml)
2nd application: Challenge undiluted semiocclusive (0.2ml)

One hundred subjects were employed in this study.  Semi-occlusive, 2 cm x 2 cm Webril pad patches were applied to the infrascapular area of the back, either to the right or left of the midline. The induction phase consisted of application of the test material every 48 hours for a total of nine applications  (applications made on Friday were not evaluated until Monday, prior to the re-application of test material) with the occlusive patch being removed after 24 hours.  The test sites were evaluated prior to each application. Following the ninth evaluation, the subjects were dismissed for a 14-day rest period. After the rest period, identical patches were applied to sites previously unexposed to test material. These patches were removed 24 hours after application and were evaluated 48 hours and 72 hours after application. Each person was considered a complete case and used for evaluation of the material if they had six or more applications and subsequent readings during the first phase and at least one reading during the final phase.
Test Subjects 
* 11 males and 97 females.
Following the second application of the test material, a significant number of subjects developed superficial epidermal erosion. It was decided to change the occlusive patch condition to semi-occlusive, applying the material to the same site beginning with the third application.
Challenge controls:
None
Positive control substance(s):
no
Positive control results:
No positive control.
Reading:
1st reading
Hours after challenge:
48
Group:
test group
Dose level:
0.2 ml undiluted
No. with + reactions:
0
Total no. in group:
100
Clinical observations:
Under the conditions employed in this study, there was no evidence of skin sensitization to the test material.
Reading:
2nd reading
Hours after challenge:
72
Group:
test group
Dose level:
0.2 ml undiluted
No. with + reactions:
0
Total no. in group:
100
Remarks on result:
other:
Group:
positive control
Remarks on result:
other: No positive control was used.
Group:
negative control
Remarks on result:
other: Not specified
Interpretation of results:
GHS criteria not met
Conclusions:
In a well conducted human patch test hexamethyldisiloxane was not sensitising to the skin of human volunteers.
Endpoint conclusion
Endpoint conclusion:
no adverse effect observed (not sensitising)
Additional information:

In a well conducted human patch test, hexamethyldisiloxane (HMDS) was not sensitising to the skin of human volunteers. At induction and challenge, 0.2 ml of the undiluted test substance was applied onto the skin of 100 human volunteers under semiocclusive dressing. The challenge application was performed in a similar way. No skin reactions were observed in any of the human volunteers (Dow Corning Corporation, 1992).

Justification for classification or non-classification

Based on the available data, no classification is proposed for sensitisation according to Regulation (EC) No 1272/2008.