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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:
23 May 2011- 19 August 2011
Reliability:
1 (reliable without restriction)
Rationale for reliability incl. deficiencies:
guideline study

Data source

Reference
Reference Type:
study report
Title:
Unnamed
Year:
2011
Report date:
2011

Materials and methods

Test guideline
Qualifier:
according to guideline
Guideline:
OECD Guideline 406 (Skin Sensitisation)
GLP compliance:
yes
Type of study:
Buehler test
Justification for non-LLNA method:
An LLNA study was not performed because there is an existing reliable study for skin sensitisation using the Buehler 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.

Test material

Reference
Name:
Unnamed
Type:
Constituent

In vivo test system

Test animals

Species:
guinea pig
Strain:
Dunkin-Hartley
Sex:
male
Details on test animals and environmental conditions:
TEST ANIMALS
- Source: information removed from study report
- Age at study initiation: 5-9 weeks
- Weight at beginning of acclimatization: 353.2 - 593 g
- Housing: in groups of 10 animals in stainless steel cages
- Diet: ad libitum
- Water: ad libitum
- Acclimation period: 26 days for control group 1 and test group. 7 days for control group 2. 4-5 days for the animals used in the irritation screens.

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

Study design: in vivo (non-LLNA)

Induction
Route:
epicutaneous, occlusive
Vehicle:
other: acetone puriss
Concentration / amount:
Induction: the test item was applied at 75% (w/w) in acetone puriss.
Challenge: 10% in acetone
Challenge
No.:
#1
Route:
epicutaneous, occlusive
Vehicle:
other: acetone puriss
Concentration / amount:
Induction: the test item was applied at 75% (w/w) in acetone puriss.
Challenge: 10% in acetone
No. of animals per dose:
Primary challenge: 20 test- and 10 control animals
Rechallenge: 10 additional untreated control animals
Two irritation screens, each with 3 animals
Details on study design:
The animals' fur was shaved with a fine clipper blade or equivalent just prior to the exposure. Closed patches were applied to the animals as follows: 0.5ml of the test item or a freshly prepared test item dilution in a 25mm Hill Top Chamber. The 25 mm Hill Top Chamber was firmly secured by an elastic plaster wrapped around the trunk of the animal and secured with impervious adhesive tape. The occlusive dressing was left in place for 6 hours. Identical patching method was used for the irritation screen, induction, challenge and rechallenge.

Induction was performed on test days 1, 8 and 15. Each animal received one patch on left shoulder per week which was remained in place for ca. 6 hours each. The patches were applied over 3 weeks. The repeated application was performed at the same site. The interval between exposures was a week. The test item was applied at 75% in acetone puriss and the control animals were treated the same way as the test animals with the vehicle (acetone puriss) only, and also covered occlusively.

After the last induction exposure, the animals were left untreated for 2 weeks before the challenge.

Any gross skin reactions were recorded without depilation.

First challenge was performed on day 29; both the control and test animals were challenged 2 weeks (14 days) after the last induction exposure. The test item was applied at 10% (highest non-irritating concentration) in acetone puriss in a similar manner used for the epidermal induction. The vehicle acetone puriss was applied too. The occlusive period was 6 hours on a naive skin site.

Because equivocal findings were observed after the first challenge, a rechallenge was carried out. The acetone control animals were not rechallenged since they were considered to be sensitised after the first challenge and no l onger "control" value. Discussion was necessary to decide on the continuation of the study with naive control animals and as the naive control animals could not be delivered immediately, the interval between first and rechallenge was extended. However, first challenge reactions, even weak ones, if they are truly allergic, can generally be reproduced over a period of at least several weeks.

The second challenge was carried out with additional control animals (control group 2) and the original test animals. The treatment was identical to the first challenge, performed 28 days after the first challenge and using new test sites. The animals were 5-17 weeks of age under the circumstances of the study, an age which was deemed not to influence the sensitivity of the test system.
Challenge controls:
Two control groups were used; one for challenge and a naive group for rechallenge.
Positive control substance(s):
yes
Remarks:
alpha-hexylcinnamaldehyde

Results and discussion

In vivo (non-LLNA)

Resultsopen allclose all
Reading:
other: Day 1, 8 and 15
Group:
negative control
Dose level:
vehicle (acetone puriss)
No. with + reactions:
0
Total no. in group:
10
Remarks on result:
no indication of skin sensitisation
Key result
Reading:
other: Application on Day 1
Group:
test chemical
Dose level:
75% acetone puriss
No. with + reactions:
8
Total no. in group:
20
Remarks on result:
positive indication of skin sensitisation
Key result
Reading:
other: Application on Day 8
Group:
test chemical
Dose level:
75% acetone puriss
No. with + reactions:
3
Total no. in group:
20
Remarks on result:
no indication of skin sensitisation
Key result
Reading:
other: Application on Day 15
Group:
test chemical
Dose level:
75% acetone puriss
No. with + reactions:
2
Total no. in group:
20
Remarks on result:
no indication of skin sensitisation
Reading:
1st reading
Hours after challenge:
24
Group:
negative control
Dose level:
10% acetone puriss
No. with + reactions:
0
Total no. in group:
10
Remarks on result:
no indication of skin sensitisation
Reading:
2nd reading
Hours after challenge:
48
Group:
negative control
Dose level:
10% acetone puriss
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:
test chemical
Dose level:
10% acetone puriss
No. with + reactions:
4
Total no. in group:
20
Remarks on result:
positive indication of skin sensitisation
Key result
Reading:
2nd reading
Hours after challenge:
48
Group:
test chemical
Dose level:
10% acetone puriss
No. with + reactions:
0
Total no. in group:
20
Remarks on result:
no indication of skin sensitisation
Reading:
1st reading
Hours after challenge:
24
Group:
negative control
Dose level:
vehicle (acetone puriss)
No. with + reactions:
0
Total no. in group:
10
Remarks on result:
no indication of skin sensitisation
Reading:
2nd reading
Hours after challenge:
48
Group:
negative control
Dose level:
vehicle (acetone puriss)
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:
test chemical
Dose level:
vehicle (acetone puriss)
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:
vehicle (acetone puriss)
No. with + reactions:
0
Total no. in group:
20
Remarks on result:
no indication of skin sensitisation
Reading:
rechallenge
Hours after challenge:
24
Group:
negative control
Dose level:
10% acetone puriss
No. with + reactions:
0
Total no. in group:
10
Remarks on result:
no indication of skin sensitisation
Reading:
rechallenge
Hours after challenge:
48
Group:
negative control
Dose level:
10% acetone puriss
No. with + reactions:
0
Total no. in group:
10
Remarks on result:
no indication of skin sensitisation
Key result
Reading:
rechallenge
Hours after challenge:
24
Group:
test chemical
Dose level:
10% acetone puriss
No. with + reactions:
0
Total no. in group:
20
Remarks on result:
no indication of skin sensitisation
Key result
Reading:
rechallenge
Hours after challenge:
48
Group:
test chemical
Dose level:
10% acetone puriss
No. with + reactions:
0
Total no. in group:
20
Remarks on result:
no indication of skin sensitisation
Reading:
rechallenge
Hours after challenge:
24
Group:
negative control
Dose level:
acetone puriss
No. with + reactions:
0
Total no. in group:
10
Remarks on result:
no indication of skin sensitisation
Reading:
rechallenge
Hours after challenge:
48
Group:
negative control
Dose level:
acetone puriss
No. with + reactions:
0
Total no. in group:
10
Remarks on result:
positive indication of skin sensitisation
Key result
Reading:
rechallenge
Hours after challenge:
24
Group:
test chemical
Dose level:
acetone puriss
No. with + reactions:
0
Total no. in group:
20
Remarks on result:
no indication of skin sensitisation
Key result
Reading:
rechallenge
Hours after challenge:
48
Group:
test chemical
Dose level:
acetone puriss
No. with + reactions:
0
Total no. in group:
20
Remarks on result:
no indication of skin sensitisation
Reading:
1st reading
Group:
positive control
Remarks on result:
other: the results confirmed alphahexylcinnamaldehyde as skin sensitizer, as it produced allergic contact dermatitis in > 15% of the test animals

Any other information on results incl. tables

No signs of systemic toxicity were observed in the animals. No skin effect was observed in the control group after treatment with acetone puriss during the three weeks of induction. Discrete/patchy erythema was observed in eight, three and two out of 20 test animals after the first, second and third weeks of induction, respectively when treated with the test item at 75% in acetone puriss.

Applicant's summary and conclusion

Interpretation of results:
GHS criteria not met
Conclusions:
The test material was found not sensitising to guinea pig skin in a reliable study conducted according to current OECD Test Guideline 406 and in compliance with GLP.