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Skin sensitisation

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Administrative data

Endpoint:
skin sensitisation: in vivo (LLNA)
Type of information:
experimental study
Adequacy of study:
key study
Study period:
9 October 2006 - 7 November 2006
Reliability:
1 (reliable without restriction)
Rationale for reliability incl. deficiencies:
guideline study

Data source

Reference
Reference Type:
study report
Title:
Unnamed
Year:
2007
Report date:
2007

Materials and methods

Test guidelineopen allclose all
Qualifier:
according to guideline
Guideline:
OECD Guideline 429 (Skin Sensitisation: Local Lymph Node Assay)
Deviations:
no
Qualifier:
according to guideline
Guideline:
EU Method B.42 (Skin Sensitisation: Local Lymph Node Assay)
Deviations:
no
GLP compliance:
yes (incl. QA statement)
Type of study:
mouse local lymph node assay (LLNA)

Test material

Reference
Name:
Unnamed
Type:
Constituent
Test material form:
solid: particulate/powder
Remarks:
white powder
Details on test material:
- Name of test material (as cited in study report): ucb108628-1
- Stability under test conditions: not indicated
- Storage condition of test material: room temperature, in the dark

In vivo test system

Test animals

Species:
mouse
Strain:
CBA
Sex:
female
Details on test animals and environmental conditions:
TEST ANIMALS
- Source: B & K Universal Ltd, Hull, UK
- Strain: CBA/Ca (CBA/CaBkl)
- Age at study initiation: eight to twelve weeks old
- Weight at study initiation: 15 to 23 g
- Housing: individually housed in suspended solid-floor polypropylene cages furnished with softwood woodflakes
- Diet (e.g. ad libitum): ad libitum
- Water (e.g. ad libitum): ad libitum
- Acclimation period: at least 5 days

ENVIRONMENTAL CONDITIONS
- Temperature (°C): 19-25
- Humidity (%): 30-70
- Air changes (per hr): ca. 15
- Photoperiod (hrs dark / hrs light): 12/12

Study design: in vivo (LLNA)

Vehicle:
dimethylformamide
Concentration:
50%, 25% or 10% (w/w) in vehicle
No. of animals per dose:
4
Details on study design:
RANGE FINDING TESTS:
- Compound solubility: butanone and acetone/olive oil (4:1) not suitable for dosing at 50% concentration
- Irritation: daily (for 3 days) application of 25 µl of test material at 50% w/w in vehicle: no signs
- Lymph node proliferation response: not applicable

MAIN STUDY
ANIMAL ASSIGNMENT AND TREATMENT
- Name of test method:
- Criteria used to consider a positive response: The test material will be regarded as a sensitiser if at least one concentration of the test material results in a threefold or greater increase in 3HTdR incorporation compared to control values. Any test material failing to produce a threefold or greater increase in 3HTdR incorporation will be classified as a "non-sensitiser".

TREATMENT PREPARATION AND ADMINISTRATION: The mice were treated by daily application of 25 μl of the appropriate concentration of the test material to the dorsal surface of each ear for three consecutive days (Days 1, 2, 3). The test material formulation was administered using an automatic
micropipette and spread over the dorsal surface of the ear using the tip of the pipette. A further group of four mice received the vehicle alone in the same manner. Five days following the first topical application of the test material (Day 6) all mice were injected via the tail vein with 250 μl of phosphate buffered saline (PBS) containing 3Hmethyl thymidine (3HTdR: 80 μCi/ml, specific activity 2.0 Ci/mmol, GE Healthcare UK Ltd) giving a total of 20 μCi to each mouse.
Positive control substance(s):
hexyl cinnamic aldehyde (CAS No 101-86-0)

Results and discussion

Positive control results:
The Stimulation Index (SI) expressed as the mean radioactive incorporation for each treatment group divided by the mean radioactive incorporation of the vehicle control group are as follows: 2.81 at 5% (v/v), 4.20 at 10% (v/v) and 13.15 at 25% (v/v). α-Hexylcinnamaldehyde, Tech, 85% was considered to be a sensitiser under the conditions of the test.

In vivo (LLNA)

Resultsopen allclose all
Key result
Parameter:
SI
Value:
0.81
Test group / Remarks:
10%
Key result
Parameter:
SI
Value:
0.81
Test group / Remarks:
25%
Key result
Parameter:
SI
Value:
1.22
Test group / Remarks:
50%
Cellular proliferation data / Observations:
The disintegrations per minute (DPM) were 6447, 5221, 5237 and 7855 for respectively the control grup and groups dosed at 10%, 25% and 50%.

Any other information on results incl. tables

There were no deaths. No signs of systemic toxicity were noted in the test or control animals during the test. White residual test material on the ears was noted, post dosing on days 1 to 3, on animals treated with the test material at a concentration of 50% w/w. Body weight changes of the test animals between day 1 and day 6 were comparable to those observed in the corresponding control group animals over the same period.

Applicant's summary and conclusion

Interpretation of results:
GHS criteria not met
Conclusions:
Base on the results of an LLNA conducted according to OECD/EC guidelines and GLP principles, the test substance was considered to be a non-sensitiser under the conditions of the test.