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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:
2009-10-12 to 2009-11-06
Reliability:
1 (reliable without restriction)
Rationale for reliability incl. deficiencies:
guideline study

Data source

Reference
Reference Type:
study report
Title:
Unnamed
Year:
2010
Report date:
2010

Materials and methods

Test guideline
Qualifier:
according to guideline
Guideline:
OECD Guideline 406 (Skin Sensitisation)
Deviations:
no
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.

Test material

Constituent 1
Chemical structure
Reference substance name:
Hexamethylcyclotrisiloxane
EC Number:
208-765-4
EC Name:
Hexamethylcyclotrisiloxane
Cas Number:
541-05-9
Molecular formula:
C6H18O3Si3
IUPAC Name:
hexamethyl-1,3,5,2,4,6-trioxatrisilinane

In vivo test system

Test animals

Species:
guinea pig
Strain:
Dunkin-Hartley
Sex:
male
Details on test animals and environmental conditions:
TEST ANIMALS
- Source: Charles River Deutschland GmbH, Stolzenseeweg 32-36, 88353 Kisslegg, GERMANY
- Age at study initiation: 4-6 wk
- Weight at study initiation: 359-445 g
- Housing: 1/Makrolon Type 4 cage
- Diet: standard diet ad libitum
- Water: drinking water ad libitum
- Acclimation period: 2 wk

ENVIRONMENTAL CONDITIONS
- Temperature (°C): 22 +/- 3
- Humidity (%): 30-70
- Air changes (per hr): 10-15
- Photoperiod (hrs dark / hrs light): 12 h/12 h

IN-LIFE DATES: From: 2009-10-12 To: 2009-11-06

Study design: in vivo (non-LLNA)

Induction
Route:
intradermal and epicutaneous
Vehicle:
corn oil
Concentration / amount:
induction: intradermal 15%; epidermal 50%
challenge epidermal: 10%
Challenge
Route:
epicutaneous, occlusive
Vehicle:
corn oil
Concentration / amount:
induction: intradermal 15%; epidermal 50%
challenge epidermal: 10%
No. of animals per dose:
test: 10
vehicle control: 5
postitive control: 10

pretest intradermal: 1
pretest epidermal: 2
Details on study design:
RANGE FINDING TESTS:
intradermal 5, 10, 15% tested in corn oil (15% was the maximum technically feasible), 1 wk following following 1:1 FCA:saline [15% was selected as highest concentration technically possible, well tolerated systemically and causing mild skin irritation.]
epidermal 10, 15, 25, 50% in corn oil (50% was the maximum technically feasible). [50% (highest techincally possible and causing mild to moderate skin irritation) was chosen for induction and 10% (the highest non-irritant concentration) was chosen for challenge.]

MAIN STUDY
A. INDUCTION EXPOSURE
- No. of exposures: 2 (intradermal-3 paired injections, topical)
- Exposure period: topical 48h
- Test groups: 10
- Control group: +ve 10; -ve 5
- Site: two rows of 3 sites, one row either side of dorsal mid-line
- Frequency of applications: intradermal treatment day 0; topical induction day 7
- Duration: induction period continues to day 21
- Concentrations:
Intradermal - test group: 1:1 FCA saline; 15% TS in corn oil; 15% TS in 1:1 FCA:saline
Intradermal - control group: 1:1 FCA saline; corn oil; 1:1 FCA:saline
Topical - test group: 50% TS in corn oil
Topical - control group: corn oil

B. CHALLENGE EXPOSURE
- No. of exposures: 1 (at two sites: TS and vehicle)
- Day(s) of challenge: day 22
- Exposure period: 24h
- Test groups: 10
- Control group: +ve 10; -ve 5
- Site: flank
- Concentrations: 10% TS in corn oil; corn oil
- Evaluation (hr after challenge): 24 and 48 h following patch removal

Challenge controls:
There were no responses from any vehicle controls at challenge (see table).
Positive control substance(s):
yes
Remarks:
3% alpha-hexylcinnamaldehyde (see table)

Results and discussion

Positive control results:
One of ten animals showed skin reactions following challenge with 1% alpha-hexylcinnamaldehyde in PEG 300, with no responses in the control group. Eight of ten responded to a 3% challenge at 24 h, and 9 of ten responded at 48 h, again there were no responses in the controls (see table).

In vivo (non-LLNA)

Resultsopen allclose all
Key result
Reading:
1st reading
Hours after challenge:
24
Group:
test chemical
Dose level:
10% test substance in corn oil
No. with + reactions:
0
Total no. in group:
10
Clinical observations:
none
Remarks on result:
no indication of skin sensitisation
Key result
Reading:
2nd reading
Hours after challenge:
48
Group:
test chemical
Dose level:
10% test substance in corn oil
No. with + reactions:
0
Total no. in group:
10
Clinical observations:
none
Remarks on result:
no indication of skin sensitisation
Key result
Reading:
1st reading
Hours after challenge:
24
Group:
negative control
Dose level:
10% test substance in corn oil
No. with + reactions:
0
Total no. in group:
5
Clinical observations:
none
Remarks on result:
no indication of skin sensitisation
Key result
Reading:
2nd reading
Hours after challenge:
48
Group:
negative control
Dose level:
10% test substance in corn 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:
corn 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:
corn oil
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:
corn 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:
corn 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:
positive control
Dose level:
1% alpha-hexylcinnamaldehyde in PEG 300
No. with + reactions:
1
Total no. in group:
10
Remarks on result:
no indication of skin sensitisation
Key result
Reading:
2nd reading
Hours after challenge:
48
Group:
positive control
Dose level:
1% alpha-hexylcinnamaldehyde in PEG 300
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:
positive control
Dose level:
3% alpha-hexylcinnamaldehyde in PEG 300
No. with + reactions:
8
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:
3% alpha-hexylcinnamaldehyde in PEG 300
No. with + reactions:
9
Total no. in group:
10
Remarks on result:
positive indication of skin sensitisation

Any other information on results incl. tables

Table 1: Incidence of dermal response to challenge dosing

GROUP

MATERIAL

INTERVAL

DERMAL SCORES*

SENSITIZATION INCIDENCE INDEX**

SEVERITY INDEX***

0

1

2

3

 

 

Test

TS 10%

24h

10/10

0/10

0/10

0/10

0/10

0

48h

10/10

0/10

0/10

0/10

0/10

0

Corn oil

24h

10/10

0/10

0/10

0/10

0/10

0

48h

10/10

0/10

0/10

0/10

0/10

0

Positive control

hexylcinnamaldehyde1%

24h

9/10

1/10

0/10

0/10

1/10

0.1

48h

10/10

0/10

0/10

0/10

0/10

0

hexylcinnamaldehyde3%

24h

2/10

8/10

0/10

0/10

8/10

0.8

48h

1/10

9/10

0/10

0/10

9/10

0.9

Vehicle control

TS 10%

24h

5/5

0/5

0/5

0/5

0/5

0

48h

5/5

0/5

0/5

0/5

0/5

0

Corn oil

24h

5/5

0/5

0/5

0/5

0/5

0

48h

5/5

0/5

0/5

0/5

0/5

0

Skin reactions were graded

0 no visible change

1 discrete or patchy erythema

2 moderate and confluent erythema

3 intense erythema and swelling

There were no signs of systemic toxicity during the study. All animals gained weight during the study and there were no significant test-article related differences in vehicle and test group mean body weight.

* Number of animals showing skin reactions at each of grades 0 -3

** Incidence Index = number of animals showing post-challenge skin reactions at either 24 or 48 hours, divided by the number of animals in the group

*** Severity Index = Sum of post-challenge test grades divided by the total number of animals tested.

 

Applicant's summary and conclusion

Interpretation of results:
GHS criteria not met
Conclusions:
In an in vivo skin sensitisation study, conducted according to OECD Test Guideline 406 and in compliance with GLP, hexamethylcyclotrisiloxane was not sensitising to the skin of guinea pigs.