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Description of key information

Skin sensitisation (OECD 406): not sensisiting

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:
23 Mar - 22 Apr 2001
Reliability:
1 (reliable without restriction)
Rationale for reliability incl. deficiencies:
other: GLP-Guideline study
Qualifier:
according to
Guideline:
OECD Guideline 406 (Skin Sensitisation)
Version / remarks:
adopted 17 Jul 1992
Deviations:
no
Qualifier:
according to
Guideline:
EU Method B.6 (Skin Sensitisation)
Deviations:
no
GLP compliance:
yes (incl. certificate)
Remarks:
The Department of Health of the Government of the United Kingdom
Type of study:
guinea pig maximisation test
Justification for non-LLNA method:
The test was done before LLNA as first-choice method for in-vivo testing was set into force.
Species:
guinea pig
Strain:
Dunkin-Hartley
Sex:
male
Details on test animals and environmental conditions:
TEST ANIMALS
- Age at study initiation: 8 - 12 weeks
- Weight at study initiation: 300 - 450 g
- Housing: singly or in pairs in solid-floor polypropylene cages furnished with woodflakes
- Diet: Guinea Pig FD1 Diet (Special Diets Services Limited, Witham, UK), ad libitum
- Water: mains tap water, ad libitum
- Acclimation period: at least 5 days

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

Route:
intradermal
Vehicle:
other: arachis oil BP
Concentration / amount:
5%
Day(s)/duration:
on Day 0; single injection
Adequacy of induction:
highest concentration used causing mild-to-moderate skin irritation and well-tolerated systemically
Route:
epicutaneous, occlusive
Vehicle:
unchanged (no vehicle)
Concentration / amount:
100%
Day(s)/duration:
on Day 7; 48 h
Adequacy of induction:
other: highest concentration used causing mild-to-moderate skin irritation
No.:
#1
Route:
epicutaneous, occlusive
Vehicle:
other: ethanol/diethylphtalate (1:1)
Concentration / amount:
75%
Day(s)/duration:
on Day 21; 24 h
Adequacy of challenge:
other: non-irritant concentration
No.:
#1
Route:
epicutaneous, occlusive
Vehicle:
unchanged (no vehicle)
Concentration / amount:
100%
Day(s)/duration:
on Day 21; 24 h
Adequacy of challenge:
highest non-irritant concentration
No. of animals per dose:
5 (controls), 10 (test groups)
Details on study design:
RANGE FINDING TESTS:
For the intradermal induction 2 concentrations of the test substance (1 and 5%) in arachis oil BP were injected intradermally into the clipped skin of two animals. The highest concentration (5%) induced only mild to moderate skin irritation and was selected for the main study. For the epicutaneous induction 2 animals (intradermally injected with FCA 10 days earlier) were treated with 4 concentrations of the test substance (25, 50, 75 and 100%). Applications were made to the clipped flanks under occlusive dressings for 48 hours. Due to a technical error arachis oil BP was used as the vehicle for formulating the test substance instead of ethanol/diethylphthalate 1:1. The highest concentration (100%) produced only mild to moderate dermal irritation and was selected for the topical induction stage of the main study.
For the epicutaneous challenge 2 animals (identically treated to the control animals of the main study up to Day 14) were treated with 4 concentrations of the test substance (25, 50 and 75% in ethanol/diethylphthalate 1:1 and 100%). Applications were made to the clipped flanks under occlusive dressings for 24 hours. The highest non-irritant concentration and one lower concentration were selected for the topical challenge stage of the main study.

MAIN STUDY
A. INDUCTION EXPOSURE
- No. of exposures: 2 (intradermal and epicutaneous, respectively)
- Exposure period: single injection (intradermal) and 48 h (epicutaneous)
- Test groups:
Intradermal (3 pairs of injections):
Injection 1: a 1:1 mixture (v/v) FCA/water
Injection 2: 5% test substance in arachis oil BP
Injection 3: 5% v/v formulation of test material in 1:1 preparation of FCA/water
Epicutaneous: test substance undiluted
- Control group:
Intradermal (3 pairs of injections):
Injection 1: a 1:1 mixture (v/v) FCA/water
Injection 2: arachis oil BP
Injection 3: 50% formulation of test material in 1:1 preparation of FCA/water
Epicutaneous: identical to the test group except that the test material was omitted
- Site: shoulder region (intradermal + epicutaneous)
- Frequency of applications: every 7 days
- Duration: Days 0 - 7
- Concentrations: intradermal 5%, epicutaneous 100%

B. CHALLENGE EXPOSURE
- No. of exposures: 1
- Day(s) of challenge: 21
- Exposure period: 24 h
- Test groups: test substance and vehicle
- Control group: test substance and vehicle
- Site: right flank (100% test substance) and left flank (75% test substance)
- Concentrations: 75 and 100%
- Evaluation: 24 and 48 h after challenge patch removal
Challenge controls:
The control group is actually a challenge control.
Positive control substance(s):
yes
Remarks:
hexylcinnamaldehyde, Induction: intradermal 5% in arachis oil BP, epicutaneous 100%, Challenge: 75 and 100% in arachis oil BP
Positive control results:
The positive control substance induced positive reactions in 4/10 animals (40%), thus meeting the reliability criteria for the Guinea Pig Maximisation Test (≥ 30% positive response). The positive control group was not carried out concurrently with this study but is a historical background data group from a study performed during January and February 2001.
Reading:
1st reading
Hours after challenge:
24
Group:
negative control
Dose level:
Challenge: 75%
No. with + reactions:
0
Total no. in group:
5
Remarks on result:
other: Reading: 1st reading. . Hours after challenge: 24.0. Group: negative control. Dose level: Challenge: 75%. No with. + reactions: 0.0. Total no. in groups: 5.0.
Reading:
1st reading
Hours after challenge:
24
Group:
negative control
Dose level:
Challenge: 100%
No. with + reactions:
0
Total no. in group:
5
Remarks on result:
other: Reading: 1st reading. . Hours after challenge: 24.0. Group: negative control. Dose level: Challenge: 100%. No with. + reactions: 0.0. Total no. in groups: 5.0.
Reading:
1st reading
Hours after challenge:
24
Group:
test group
Dose level:
Challenge: 75%
No. with + reactions:
0
Total no. in group:
10
Remarks on result:
other: Reading: 1st reading. . Hours after challenge: 24.0. Group: test group. Dose level: Challenge: 75%. No with. + reactions: 0.0. Total no. in groups: 10.0.
Reading:
1st reading
Hours after challenge:
24
Group:
test group
Dose level:
Challenge: 100%
No. with + reactions:
0
Total no. in group:
10
Remarks on result:
other: Reading: 1st reading. . Hours after challenge: 24.0. Group: test group. Dose level: Challenge: 100%. No with. + reactions: 0.0. Total no. in groups: 10.0.
Reading:
2nd reading
Hours after challenge:
48
Group:
negative control
Dose level:
Challenge: 75%
No. with + reactions:
0
Total no. in group:
5
Remarks on result:
other: Reading: 2nd reading. . Hours after challenge: 48.0. Group: negative control. Dose level: Challenge: 75%. No with. + reactions: 0.0. Total no. in groups: 5.0.
Reading:
2nd reading
Hours after challenge:
48
Group:
negative control
Dose level:
Challenge: 100%
No. with + reactions:
0
Total no. in group:
5
Remarks on result:
other: Reading: 2nd reading. . Hours after challenge: 48.0. Group: negative control. Dose level: Challenge: 100%. No with. + reactions: 0.0. Total no. in groups: 5.0.
Reading:
2nd reading
Hours after challenge:
48
Group:
test group
Dose level:
Challenge: 75%
No. with + reactions:
0
Total no. in group:
10
Remarks on result:
other: Reading: 2nd reading. . Hours after challenge: 48.0. Group: test group. Dose level: Challenge: 75%. No with. + reactions: 0.0. Total no. in groups: 10.0.
Reading:
2nd reading
Hours after challenge:
48
Group:
test group
Dose level:
Challenge: 100%
No. with + reactions:
0
Total no. in group:
10
Remarks on result:
other: Reading: 2nd reading. . Hours after challenge: 48.0. Group: test group. Dose level: Challenge: 100%. No with. + reactions: 0.0. Total no. in groups: 10.0.

Discrete or patchy to moderate and confluent erythema was noted at the intradermal induction sites of test group animals.

Discrete or patchy to moderate and confluent erythema was noted at the intradermal induction sites of control group animals.

Discrete or patchy to moderate and confluent erythema and an isolated incident of very slight oedema were noted at the topical induction sites of test group animals.

No skin reactions were noted at the topical induction sites of control group animals.

No skin reactions were noted at the challenge sites of the test or control group animals at the 24- or 48-hour observations.

Interpretation of results:
not sensitising
Remarks:
Migrated information Criteria used for interpretation of results: EU
Conclusions:
Under the conditions of the guinea pig maximisation test the test substance revealed no sensitising properties.
Endpoint conclusion
Endpoint conclusion:
no adverse effect observed (not sensitising)
Additional information:

The skin sensitising potential of the test substance was investigated in a guinea pig maximisation test (GPMT test) according to OECD Guideline 406 and in compliance with GLP (2001). A range finding study was performed to determine the appropriate dose level of the test substance in arachis oil BP following intradermal and epicutaneous administrations. Based on the results of the preliminary study, a 5% solution of the test substance in arachis oil BP was selected for the first induction stage (intradermal) on Day 0 and the undiluted test substance for the second induction stage (epicutaneous) on Day 7. A 75% solution of the test substance in ethanol/diethylphthalate 1:1 and the undiluted test substance were selected for the challenge on Day 21.

In the main study, 10 animals were used to investigate the skin sensitising potential of the test substance. In addition, 5 animals treated with arachis oil BP only served as vehicle reference. In the first induction stage on Day 0, discrete or patchy to moderate and confluent erythema was noted at the intradermal induction sites of the test or control group animals 24 and 48 h after administration. In the second induction stage on Day 7, a filter paper patch saturated with the undiluted test substance was applied to the clipped flanks under occlusive dressings for 48 h. Discrete or patchy to moderate and confluent erythema and an isolated incident of very slight oedema were noted at the topical induction sites of the test group animals. No skin reactions were noted at the topical induction sites of the control group animals. On Day 21, the animals were challenged with the 75% solution of the test substance in ethanol/diethylphthalate 1:1 and the undiluted test substance by occluded patches for 24 h to the left and right flank, respectively. No skin reactions at the challenge sites of the test or control group animals were observed 24 and 48 h after challenge patch removal. Based on the results of this GPMT, the test substance was not regarded as a skin sensitizer under the conditions of the test.


Migrated from Short description of key information:
skin sensitisation (OECD 406): not sensitising

Justification for selection of skin sensitisation endpoint:
The reliable GLP compliant OECD Guideline study was chosen.

Respiratory sensitisation

Endpoint conclusion
Endpoint conclusion:
no study available
Additional information:

Justification for selection of respiratory sensitisation endpoint:
Study not required according to Annex VII-X of Regulation (EC) No 1907/2006.

Justification for classification or non-classification

The available data on sensitisation of the test substance do not meet the criteria for classification according to Regulation (EC) 1272/2008, and are therefore conclusive but not sufficient for classification.