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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
Reliability:
2 (reliable with restrictions)
Rationale for reliability incl. deficiencies:
data from handbook or collection of data
Justification for type of information:
data is from peer reviewed journals

Data source

Reference
Reference Type:
publication
Title:
The Freund's Complete Adjuvant Test and the Open Epicutaneous Test
Author:
G. Klecak
Year:
1985
Bibliographic source:
Curr. Probl. Derm., vol.14, pp.152-171 (Karger, Basel 1985)

Materials and methods

Test guideline
Qualifier:
according to
Guideline:
other: as mentuined below
Principles of method if other than guideline:
An Open Epicutaneous Test (OET) was performed on guinea pigs to assess the skin sensitization potential of test chemical
GLP compliance:
not specified
Type of study:
not specified
Justification for non-LLNA method:
not specified

Test material

Reference
Name:
Unnamed
Type:
Constituent
Details on test material:
- Name of test material:3,7-dimethyloct-6-en-1-yl 2-methylpropanoate
- Common Name: Citronellyl isobutyrate
- Molecular formula: C14H26O2
- Molecular weight : 226.3574 g/mol
- Smiles notation :C(OCC[C@@H](CC\C=C(\C)C)C)(C(C)C)=O
- InChl:1S/C14H26O2/c1-11(2)7-6-8-13(5)9-10-16-14(15)12(3)4/h7,12-13H,6,8-10H2,1-5H3
- Substance type: Organic
- Physical state: Liquid

In vivo test system

Test animals

Species:
guinea pig
Strain:
not specified
Sex:
male/female
Details on test animals and environmental conditions:
- Weight at study initiation: 300-450g

Study design: in vivo (non-LLNA)

Induction
Route:
epicutaneous, open
Vehicle:
other: ethanol, acetone, H20, petroleum, PEG and/or other suitable vehicles
Concentration / amount:
Concentration:4%
Amount: 0.1ml
Day(s)/duration:
3 weeks (0-21 days)
Adequacy of induction:
not specified
Challenge
No.:
#1
Route:
epicutaneous, open
Vehicle:
other: ethanol, acetone, H20, petroleum, PEG and/or other suitable vehicles
Concentration / amount:
4% - 0.025 ml
Day(s)/duration:
72 hours
Adequacy of challenge:
not specified
No. of animals per dose:
6–8 male and female guinea pigs
Details on study design:
RANGE FINDING TESTS: The Pretest was performed to establish the primary irritating threshold concentration of test substance. For this, a single application of 0.025 ml of each test concentration (e.g, 100, 30, 10 and 3%) is simultaneously performed on one of the areas measuring 2 cm2 of the flank skin previously clipped and marked with a circular stamp. Reactions are read 24 h after the application of the test material. On the basis of preliminary study, the maximal non-irritating concentration selected was 8%. Thus the sensitization test was conducted at a dose of 4% of test chemical.

MAIN STUDY
A. INDUCTION EXPOSURE
- No. of exposures: 21
- Exposure period:24 hours
- Test groups:6-8 guinea pigs
- Control group:3 guinea pigs
- Site: an area measuring 8 cm2 on the clipped flank skin of the guinea pigs
- Frequency of applications: The applications are repeated daily for 3 weeks or done 5 times weekly during 4 weeks
- Duration: 21 days (3 weeks)
- Concentrations: 4% in vehicle.
Amount: 0.1ml

B. CHALLENGE EXPOSURE
- No. of exposures: 2
- Day(s) of challenge: on days 21 and 35
- Exposure period:24 hours
- Test groups: 6-8 guinea pigs
- Control group: 3 guinea pigs
- Site: contralateral flank measuring 2 cm2
- Concentrations: Concentration:4%
Amount: 0.025ml
- Evaluation (hr after challenge): 24,48 and/or 72h.
Challenge controls:
The 10 controls were either left untreated or treated with 0.1 ml aliquot of the vehicle for 21 days
Positive control substance(s):
not specified

Results and discussion

In vivo (non-LLNA)

Results
Reading:
1st reading
Hours after challenge:
72
Group:
test group
Dose level:
4%
No. with + reactions:
0
Total no. in group:
6
Clinical observations:
no signs of dermal sensitization pbserved
Remarks on result:
no indication of skin sensitisation

Applicant's summary and conclusion

Conclusions:
The test chemical was considered to be not sensitizing on skin of guinea pigs at concentration of 4% in an Open Epicutaneous Test (OET).
Executive summary:

An Open Epicutaneous Test (OET) was performed on guinea pigs to assess the skin sensitization potential of test chemical.

 

The Pretest was performed to establish the primary irritating threshold concentration of test substance. For this, a single application of 0.025 ml of each test concentration (e.g, 100, 30, 10 and 3%) is simultaneously performed on one of the areas measuring 2 cm2 of the flank skin previously clipped and marked with a circular stamp. Reactions are read 24 h after the application of the test material. On the basis of preliminary study, the maximal non-irritating concentration selected was 4%. Thus the sensitization test was conducted at a dose of 4% of test chemical.

 

On day 1 during induction, 0.1 ml of test chemical was applied at concentrations of 4% in vehicle to an area measuring 8 cm2 on the clipped flank skin of the guinea pigs. The applications are repeated daily for 3 weeks or done 5 times weekly during 4 weeks, usually on the same skin sites. The application sites were left uncovered and the reactions, if continuous daily applications were performed, can be read 24 h after each application, or at the end of each week. 

To determine whether or not contact sensitization was induced, all groups of guinea pigs previously treated for 21 days, as well as 10 untreated, or only pretreated with the vehicle, controls are tested on days 21 and 35 on the contralateral flank with the test material. This test was performed by applying with a pipette 0.025 ml of each concentration to skin areas measuring 2 cm2. The reactions were read after 24, 48 and/or 72h.

 

It was observed that none of the guinea pigs induced contact sensitization at challenge concentration of 4%.Thus, the test chemical was considered to be not sensitizing on skin of guinea pigs at concentration of 4% in an Open Epicutaneous Test (OET).