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Toxicological information

Skin sensitisation

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Administrative data

Endpoint:
skin sensitisation: in vivo (LLNA)
Type of information:
experimental study
Adequacy of study:
key study
Reliability:
2 (reliable with restrictions)
Rationale for reliability incl. deficiencies:
comparable to guideline study with acceptable restrictions

Data source

Reference
Reference Type:
publication
Title:
Human potency predictions for aldehydes using the local lymph node assay
Author:
Basketter et al.
Year:
2001
Bibliographic source:
Contact Dermatitis, Vol. 45, pp. 89-94

Materials and methods

Test guideline
Qualifier:
equivalent or similar to
Guideline:
OECD Guideline 429 (Skin Sensitisation: Local Lymph Node Assay)
GLP compliance:
no
Type of study:
mouse local lymph node assay (LLNA)

Test material

Reference
Name:
Unnamed
Type:
Constituent

In vivo test system

Test animals

Species:
mouse
Strain:
other: CBA/Ca
Sex:
female
Details on test animals and environmental conditions:
TEST ANIMALS
- Age at study initiation: 6-12 weeks
- Housing: under standard conditions
- Diet: ad libitum
- Water: tap water, ad libitum
- Acclimation period: 5 days

No further data

Study design: in vivo (LLNA)

Vehicle:
acetone/olive oil (4:1 v/v)
Concentration:
Test substance and positive control: 1, 2.5, 5, 10, 25 and 50%
No. of animals per dose:
4
Details on study design:
ANIMAL ASSIGNMENT AND TREATMENT
- Name of test method: 3H-methyl thymidine incorporation determined by ß-scintillation
- Criteria used to consider a positive response: A stimulation index (SI) relative to the concurrent vehicle treated control value was calculated for each group. The criterion for a positve response is that one or more concentrations of the test substance should elicit a 3-fold or greater increase in isotope incorporation relative to the vehicle control group.

TREATMENT PREPARATION AND ADMINISTRATION: The dorsal surface of both ears was topically treated (25 μL/ear) with the test substance daily for 3 consecutive days. Five days after initiation of exposure an injection of 250 µL phosphate buffered saline (PBS) containing 20 µCi of 3H-methyl thymidine (³HTdR) was made into the tail vein of each experimental mouse. Five hours later, following injection of ³HTdR, the mice were sacrificed and draining auricular lymph nodes were excised and pooled for each experimental group. A single cell suspension was prepared by gentle separation through a 200 mesh stainless steel gauze. The cell suspensions were washed two times with an excess of PBS and precipitated with 5% trichloroacetic acid at 4 °C for 12 h. The pellets were resuspended in 1 mL of 5% trichloroacetic acid and transferred to 10 mL of scintillation fluid.
Positive control substance(s):
hexyl cinnamic aldehyde (CAS No 101-86-0)
Statistics:
The EC3 value was calculated by interpolating between 2 points on the SI axis, one immediately above, and the other immediately below, the SI value of 3. The vehicle-treated control (SI=1) cannot be used for the latter. Where the data points lying immediately above and below the SI value of 3 have the co-ordinates (a, b) and (c, d) respectively, then the EC3 value may be calculated using the following equation: EC3 = c + [(3 - d)/(b - d)] × (a - c)

Results and discussion

Positive control results:
The EC3 value calculated for the positive control was 14.7.

In vivo (LLNA)

Resultsopen allclose all
Key result
Parameter:
SI
Value:
0.73
Test group / Remarks:
1% (w/v)
Key result
Parameter:
SI
Value:
1.76
Test group / Remarks:
2.5% (w/v)
Key result
Parameter:
SI
Value:
7.84
Test group / Remarks:
5% (w/v)
Key result
Parameter:
SI
Value:
8.76
Test group / Remarks:
10% (w/v)
Key result
Parameter:
SI
Value:
18.96
Test group / Remarks:
25% (w/v)
Key result
Parameter:
EC3
Value:
3
Key result
Parameter:
other: disintegrations per minute (DPM)
Value:
185
Test group / Remarks:
1% (w/v)
Key result
Parameter:
other: disintegrations per minute (DPM)
Value:
450
Test group / Remarks:
2.5% (w/v)
Key result
Parameter:
other: disintegrations per minute (DPM)
Value:
2 000
Test group / Remarks:
5% (w/v)
Key result
Parameter:
other: disintegrations per minute (DPM)
Value:
2 233
Test group / Remarks:
10% (w/v)
Key result
Parameter:
other: disintegrations per minute (DPM)
Value:
4 834
Test group / Remarks:
25% (w/v)

Applicant's summary and conclusion

Interpretation of results:
other: Skin Sens Cat 1B is required according to Regulation (EC) No 1272/2008
Conclusions:
Under the conditions of the mouse Local Lymph Node Assay the test substance revealed a SI ≥ 3.0 at concentrations of 5, 10 and 25%. The EC3 value was 3.0%. Therefore, the test substance is considered as a moderate sensitiser.