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Diss Factsheets

Administrative data

Description of key information

There are no available skin sensitisation data for the registered substance "Reaction Mass of decamethyltetrasiloxane; dodecamethylpentasiloxane; hexamethyldisiloxane; octamethyltrisiloxane". Therefore, data have been read-across from its constituents, HMDS and L3.

The first skin sensitisation study for HMDS is a well conducted human patch test performed in compliance with GLP (TKL research, 1992). In this study HMDS was not sensitising to the skin of human volunteers.

The second skin sensitisation study for HMDS is a guinea pig maximisation study conducted using a study protocol comparable with OECD 406 and to GLP (Dow Corning Corporation, 1992). HMDS was not sensitising to the skin.

The skin sensitisation study for L3 was conducted according to OECD 406 and to GLP. The test substance was observed to be not sensitising to the skin of guinea-pig (RCC 1999).

Key value for chemical safety assessment

Skin sensitisation

Link to relevant study records

Referenceopen allclose all

Endpoint:
skin sensitisation: in vivo (non-LLNA)
Type of information:
experimental study
Adequacy of study:
weight of evidence
Study period:
10/09/1991 to 13/01/1992
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. 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
- Source: Charles River Breeding Laboratory
- Age at study initiation: No data
- Weight at study initiation: 338-387 g
- Housing: Individually in stainless steel cages
- Diet (e.g. ad libitum): Ad libitum
- Water (e.g. ad libitum): Ad libitum
- Acclimation period: 7 days

ENVIRONMENTAL CONDITIONS
- Temperature (°C): No data
- Humidity (%): No data
- Air changes (per hr): No data
- Photoperiod (hrs dark / hrs light): No data

IN-LIFE DATES: From: 09/10/1991 To: 02/11/1991
Route:
intradermal and epicutaneous
Vehicle:
other: ethanol and saline (unchanged (at challange))
Concentration / amount:
Various concentrations used in the induction phase, and HMDS was undiluted in the challenge phase.
Route:
epicutaneous, occlusive
Vehicle:
other: ethanol and saline (unchanged (at challange))
Concentration / amount:
Various concentrations used in the induction phase, and HMDS was undiluted in the challenge phase.
No. of animals per dose:
15; 10 males in the test group and 5 males in the negative control group. 
Details on study design:
Preliminary test:

The hair of both flanks was clipped prior to dosing. Various concentrations (25, 50, 75 and 100%) of HMDS were applied to the cotton pads of Hilltop Chambers and then applied to the flank skin. The sites were then wrapped with adhesive tape and unwrapped after approximately 24 hours and evaluated for erythema and oedema.

Main study:

For the first stage of induction, an area over the shoulder region was clipped on each animal. Three pairs of intradermal injections (0.1 ml each) were made simultaneously on previously identified sites (A, B and C), so that there was a row of three injections on each side of the spine. The injection sites were just within the boundaries of a 2x4 cm patch which was applied one week later. Injections were administered as follows:

Test substance:
A: 0.1 ml of a 50% suspension of FCA in saline.
B: 0.1 ml of 5% HMDS in 80% ethanol (suspension).
C: 0.1 ml of 10% HMDS in 80% ethanol + 50% FCA in saline (suspension).

Negative controls:
A: 0.1 ml of 50% suspension of FCA in saline.
B: 0.1 ml of 80% ethanol (solution).
C: 0.1 ml of 80% ethanol + 50% FCA in saline (suspension).

On day 7 the area of injections was clipped in preparation for the second induction. Patches of filter paper were saturated with the following solutions: a) test group - undiluted HMDS and b) negative controls - 80% ethanol. The patches were positioned on the intradermal injection sites and secured in place with an occlusive bandage for 48 hours and then unwrapped.

The challenge phase began two weeks following topical induction. The animals were prepared by clipping a 5x5 cm area on both flanks. For dosing, 0.3 ml of the test (100%) or control ethanol solutions were applied to a Hilltop Chamber (occlusive) and the chamber applied to the flank area and wrapped with gauze dressing and adhesive tape for 24 hours.

The wrappings were removed 24 hours later and the readings were made at 24 and 48 hours after patch removal and scored for erythema and oedema. Body weights were taken at the beginning of the study and at 7, 14 and 21 days. Erythema or oedema at least two grades higher than that seen in the negative control group was considered evidence of an allergic response.
Challenge controls:
Ethanol solution
Positive control substance(s):
no
Key result
Reading:
1st reading
Hours after challenge:
24
Group:
test chemical
Dose level:
100%
No. with + reactions:
0
Total no. in group:
10
Clinical observations:
No evidence of skin irritation or sensitization following challenge phase. Intradermal injection sites showed necrosis and scabbing typical of Freund's Complete Adjuvant response. No obvious effects on body weight gain or food consumption.
Remarks on result:
no indication of skin sensitisation
Key result
Reading:
2nd reading
Hours after challenge:
48
Group:
test chemical
Dose level:
100%
No. with + reactions:
0
Total no. in group:
10
Remarks on result:
no indication of skin sensitisation
Key result
Reading:
1st reading
Hours after challenge:
24
Group:
negative control
Dose level:
Ethanol
No. with + reactions:
0
Total no. in group:
5
Remarks on result:
no indication of skin sensitisation
Key result
Reading:
2nd reading
Hours after challenge:
48
Group:
negative control
Dose level:
Ethanol
No. with + reactions:
0
Total no. in group:
5
Remarks on result:
no indication of skin sensitisation
Key result
Reading:
1st reading
Group:
positive control
Remarks on result:
other: not included in the study.
Interpretation of results:
GHS criteria not met
Conclusions:
In a guinea pig maximisation study conducted using a study protocol comparable with OECD 406 and to GLP (reliability score 1) HMDS was not sensitising to the skin.
Endpoint:
skin sensitisation: in vivo (non-LLNA)
Type of information:
experimental study
Adequacy of study:
weight of evidence
Study period:
02.12.1991 to 10.01.1992
Reliability:
2 (reliable with restrictions)
Rationale for reliability incl. deficiencies:
comparable to guideline study with acceptable restrictions
Remarks:
The study was not conducted in compliance with GLP, but with Good Clinical Practice.
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:
no
Remarks:
Conducted with Good Clinical Practice (GCP)
Type of study:
patch test
Justification for non-LLNA method:
The study was well documented and meets generally accepted scientific principles. The study was not conducted in compliance with GLP, but with GCP.
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 (0.2 ml)
2nd application: Challenge undiluted semiocclusive (0.2 ml)

One hundred subjects were enrolled 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 (enrolled).
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.
Key result
Reading:
1st reading
Hours after challenge:
48
Group:
test chemical
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.
Key result
Reading:
2nd reading
Hours after challenge:
72
Group:
test chemical
Dose level:
0.2 ml undiluted
No. with + reactions:
0
Total no. in group:
100
Group:
positive control
Remarks on result:
other: positive control group was not included
Group:
negative control
Remarks on result:
other: negative control group was not included
Interpretation of results:
GHS criteria not met
Conclusions:
In a well conducted human patch test conducted to GCP (reliability score 2) L2 was not sensitising to the skin of human volunteers.
Endpoint:
skin sensitisation: in vivo (non-LLNA)
Type of information:
experimental study
Adequacy of study:
key study
Study period:
01 Dec 1998 - 15 Feb 1999
Reliability:
1 (reliable without restriction)
Rationale for reliability incl. deficiencies:
guideline study
Qualifier:
according to guideline
Guideline:
OECD Guideline 406 (Skin Sensitisation)
Qualifier:
according to guideline
Guideline:
EU Method B.6 (Skin Sensitisation)
GLP compliance:
yes (incl. QA statement)
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. 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:
other: Ibm: GOHI; SPF- quality guinea pigs
Sex:
male/female
Details on test animals and environmental conditions:
TEST ANIMALS
- Source: RCC Ltd, Biotechnology & Animal Breeding Division, Wolferstrasse 4, CH-4414 Fullinsdorf, Switzerland
- Age at study initiation: 5-7 weeks
- Weight at beginning of acclimation period: 304-380 g
- Housing: Individually in Makrolon type-4 cages with standard softwood bedding
- Diet: ad libitum
- Water: ad libitum
- Acclimation period: One week for the control and test group under test conditions after health examination. No acclimation of animals of the pretest. Only animals without any visible signs of illness were used.

ENVIRONMENTAL CONDITIONS
- Temperature (°C): 17-23
- Humidity (%): 30-70
- Air changes (per hr): 10-15
- Photoperiod (hrs dark / hrs light): 12/12

Route:
intradermal and epicutaneous
Vehicle:
olive oil
Concentration / amount:
Induction 100%, challenge 50%, positive control: intradermal induction 5% , epidermal induction 50% , challenge 50% (vehicle mineral oil)
Route:
epicutaneous, occlusive
Vehicle:
olive oil
Concentration / amount:
Induction 100%, challenge 50%, positive control: intradermal induction 5% , epidermal induction 50% , challenge 50% (vehicle mineral oil)
No. of animals per dose:
Control group: 5
Test group: 10
Intradermal pretest: 1
Epidermal pretest: 2
Positive control: 10 test, 5 control
Details on study design:
PRE TEST: This was carried out to identify a suitable concentration of the test article for the induction phase of the main study and a non-irritant concentration for the challenge phase. The concentrations tested were for the epidermal application the most qualified to assure an optimum technical application procedure and for the intradermal injection the selected concentrations were tested at 1, 3 and 5%.

MAIN STUDY:

INTRADERMAL INJECTIONS (DAY 1)

Three pairs of intradermal injections (0.1 ml/sire) were made at the border of a 4x6 cm area in the clipped region as follows:

TEST GROUP:
1. 1:1 (v/v) mixture of FCA and physiological saline.
2. The test article, at 5% in olive oil.
3. The test article at 5% in a 1:1 (v/v) mixture of FCA and physiological saline
CONTROL GROUP:
1. 1:1 (v/v) mixture of FCA and physiological saline.
2. Olive oil.
3. 1:1 (w/w) mixture of olive oil in a 1:1 (v/v) mixture of FCA and physiological saline.


EPIDERMAL APPLICATIONS (DAY 8)

TEST GROUP:
One week after the injections the scapular area was shaved free of hair again prior to the epidermal application. Filter paper was saturated with the undiluted test material and placed over the injection sites of the test animals. The volume of the test article was ca. 0.3 ml. The patch was covered with aluminium foil and firmly secured by an elastic plaster wrapped around the trunk of the animal and secured with impervious adhesive tape. The dressings were left in place for 48 hours. The epidermal application procedure described ensured intensive contact of the test article. The reaction sites were assessed for erythema and oedema 24 and 48 hours after removal of the dressing, using the numerical grading system according to Draize.

CONTROL GROUP:
The guinea pigs of the control group were treated as described above with olive oil only, also applied at a volume of ca. 0.3 ml.

CHALLENGE TEST (DAY 22)

The test and control animals were challenged two weeks after the epidermal induction application. The test and control guinea pigs were treated in the same way.
Hair was clipped and shaved from a 5x5 cm area on the left and right flank of each guinea pig just prior to application. Two patches of filter paper were saturated with the test article at the highest non-irritating concentration of 50% (left flank) and the vehicle only (olive oil applied to the right flank) using the same method as for the epidermal application. The volume of test article or vehicle applied was approximately 0.2 ml. The dressings were left in place for 24 hours.
After ca. 21 hours after removal of the dressing the test sites treated with the test article were depilated as described in the epidermal pretest. Approximately 24 and 48 hours after the removal of the dressing the application sites were assessed for erythema and oedema using the numerical scoring system according to Draize.
Challenge controls:
Challenge controls were treated in the same way as the test group.
Positive control substance(s):
yes
Remarks:
2-mercaptobenzothiazole
Key result
Reading:
1st reading
Hours after challenge:
24
Group:
positive control
Dose level:
10%
No. with + reactions:
9
Total no. in group:
10
Remarks on result:
positive indication of skin sensitisation
Key result
Reading:
2nd reading
Hours after challenge:
48
Group:
positive control
Dose level:
10%
No. with + reactions:
10
Total no. in group:
10
Remarks on result:
positive indication of skin sensitisation
Key result
Reading:
1st reading
Hours after challenge:
24
Group:
negative control
Dose level:
50% in olive oil
No. with + reactions:
0
Total no. in group:
5
Remarks on result:
no indication of skin sensitisation
Key result
Reading:
2nd reading
Hours after challenge:
48
Group:
negative control
Dose level:
50% in olive oil
No. with + reactions:
0
Total no. in group:
5
Remarks on result:
no indication of skin sensitisation
Key result
Reading:
1st reading
Hours after challenge:
24
Group:
test chemical
Dose level:
50% in olive oil
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:
test chemical
Dose level:
50% in olive oil
No. with + reactions:
0
Total no. in group:
10
Remarks on result:
no indication of skin sensitisation
Interpretation of results:
GHS criteria not met
Conclusions:
The test material was found not sensitising in a reliable study conducted according to an appropriate test protocol, and in compliance with GLP.
Endpoint conclusion
Endpoint conclusion:
no adverse effect observed (not sensitising)
Additional information:

There are no available skin sensitisation data for the registered substance "Reaction Mass of decamethyltetrasiloxane; dodecamethylpentasiloxane; hexamethyldisiloxane; octamethyltrisiloxane".

Therefore, data have been read-across from two of its constituents:

1) HMDS: hexamethyldisiloxane (CAS 107-46-0)

2) L3: octamethyltrisiloxane (CAS 107-51-7)

In a well conducted human patch test for HMDS, conducted to GLP (TKL Research, 1992) 100 subjects were exposed to an induction and challenge dose of undiluted HMDS under semi-occlusive conditions. There was no evidence of skin sensitisation under the conditions of this study.

In a guinea pig maximisation study for HMDS conducted using a study protocol comparable with OECD 406 and to GLP (Dow Corning Corporation, 1992), guinea pigs were initially exposed to 25, 50, 75 or 100% HMDS (in vehicle "ethanol") to determine the irritating potential. Since no irritation was observed in the preliminary test, undiluted HMDS was used in the main test. There was no evidence of skin irritation or skin sensitisation following the challenge phase. Intradermal injection sites showed necrosis and scabbing typical of Freund's Complete Adjuvant response. There were no significant effects on body weight gain or food consumption.

The available skin sensitisation study for L3 was conducted according to an appropriate OECD test guideline, and in compliance with GLP. None of the test animals showed any signs of sensitisation (RCC 1999).

Read-across from constituents justification

A detailed read-across explanation is available in Section 7.5.

Reaction Mass of decamethyltetrasiloxane; dodecamethylpentasiloxane; hexamethyldisiloxane; octamethyltrisiloxane (EC No 946-797-7) belongs to the structural class of siloxanes. All the substances have high log Kow (increasing with increasing chain length) and low water solubility. In vivo skin sensitisation data are available for a number of these substances.

The available studies for the linear siloxanes from this analogue group, as well as key physicochemical properties, are summarised in the table below. There is no evidence from any of the available studies that the substances in this group have any potential for skin sensitisation. It is therefore valid to read-across the lack of sensitisation potential between the members of the group where there are data gaps. The most recent and reliable studies for the substance’s constituents were chosen for weight of evidence.

Summary of key skin sensitisation data for linear siloxanes

Substance

HMDS

L3

L4

L5

Chemical name

Hexamethyldisiloxane

Octamethyltrisiloxane

Decamethyltetrasiloxane

Dodecamethylpentasiloxane

CAS number

107-46-0

107-51-7

141-62-8

141-63-9

Skin sensitising result

Not sensitising (Dow Corning Corporation, 1992)

Not sensitising (RCC, 1999)

-

-

Justification for classification or non-classification

Based on the available data for Reaction Mass of decamethyltetrasiloxane; dodecamethylpentasiloxane; hexamethyldisiloxane; octamethyltrisiloxane constituents, no classification is required for skin sensitisation according to Regulation (EC) No 1272/2008.