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Toxicological information

Skin sensitisation

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Administrative data

Endpoint:
skin sensitisation: in vivo (LLNA)
Type of information:
migrated information: read-across from supporting substance (structural analogue or surrogate)
Adequacy of study:
supporting study
Study period:
27 February 2007 to 6 March 2007
Reliability:
1 (reliable without restriction)
Rationale for reliability incl. deficiencies:
other: The study was conducted according to generally valid and/or internationally accepted testing guidelines. The test substance was identified by name only. No structural characterization or purity information was available.

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:
OECD Guideline 429 (Skin Sensitisation: Local Lymph Node Assay)
Deviations:
no
Qualifier:
according to
Guideline:
EPA OPPTS 870.2600 (Skin Sensitisation)
Deviations:
no
GLP compliance:
yes (incl. certificate)
Type of study:
mouse local lymph node assay (LLNA)

Test material

Reference
Name:
Unnamed
Type:
Constituent
Type:
Constituent
Type:
Constituent
Details on test material:
Name: LLNA-965
Source: IFF
Color: Clear
Physical State: Liquid
Batch Ref. No.: Lot SM/6043085
CTL Test Substance No.: Y13980/001
Purity (% w/w): 98.2%
Storage Conditions: Ambient in the dark
Expiry: October 2007

The material was identified as dimyrcetol (CAS 18479-58-8).

In vivo test system

Test animals

Species:
mouse
Strain:
other: CBA/Ca
Sex:
female
Details on test animals and environmental conditions:
TEST ANIMALS
- Source: Charles River UK Ltd., Manston Road, Margate, Kent, UK
- Age at study initiation: 8-12 weeks
- Weight at study initiation: 16.9 to 22.3 g
- Housing: A maximum of 4 mice/cage
- Diet (ad libitum): RM1, Special Diet Services Ltd., Witham, Essex, UK
- Water (ad libitum): mains
- Acclimation period: At least 5 days prior to start of dosing


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


IN-LIFE DATES: From: 27 February 2007 To: 6 March 2007

Study design: in vivo (LLNA)

Vehicle:
other: 1:3 Ethanol:Diethylphthalate (CTL Ref: Y05722/002)
Concentration:
0.5, 1, 2.5, 10 or 25% w/v
No. of animals per dose:
4
Details on study design:
Dose Preparation:
All dose preparations were used within 24 hours. Stability and achieved concentrations were not determined.

Test Method Details:
Groups of 4 mice were used at each dose level. Approximately 25 microliters of 0.5, 1, 2.5, 10 or 25% w/v preparations of the test substance in vehicle were applied to the dorsal surface of each ear. A vehicle control group was similarly treated with vehicle alone. This procedure was repeated daily for 3 consecutive days.

Three days after the last application, all animals were injected with approx. 250 microliters of phosphate buffered saline containing 20 microCuries of a 2.0 Ci/mmol specific activity of 3H-methyl thymidine. Approximately 5 hours later, the animals were humanely killed by inhalation of halothane vapour followed by cervical dislocation. The draining auricular lymph nodes were removed from each animal and, together with the nodes from the other animals in the group, were placed in a container of PBS.

A single cell suspension was prepared by mechanical disaggregation of lymph nodes through a 200-mesh stainless steel gauze. The cell suspensions were then washed three times by centrifugation with approximately 10 ml of PBS. Approximately 3 ml of 5% w/v trichloroacetic acid (TCA) was added and, after overnight precipitation at 4 deg C, the samples were pelleted by centrifugation and the supernatant was discarded. The cells were resuspended in approx. 1 ml of TCA.

The lymph node suspensions were transferred to scintillation vials and 10 ml of scintillant (Optiphase) was added prior to beta-scintillation counting using a Packard Tri-Carb 3100TR Liquid Scintillation Counter.

Clinical Observations:
Animals were checked at least once daily for signs of systemic toxicity. Animals were monitored for any signs of irritancy on the ears on days 1, 2, 3 and 6 of study. Irritancy was scored at a visual level with the scoring scheme of none detectable, mild, moderate or severe.

Body Weights:
The body weight of each animal was recorded prior to dosing on day 1 and prior to injection of the 3H-methyl thymidine on day 6.

Positive Control:
Approximately 25 microliters of 5%, 10% or 25% of the positive control in acetone in olive oil (4:1) was applied, and a vehicle control of acetone:olive oil was similarly treated.
Positive control substance(s):
hexyl cinnamic aldehyde (CAS No 101-86-0)
Statistics:
None described

Results and discussion

Positive control results:
The application of the positive control substance at the 25% w/v concentration resulted in greater than a 3-fold increase in isotope incorporation.

In vivo (LLNA)

Results
Parameter:
SI
Remarks on result:
other: The concentration giving rise to a 3-fold increase in lymphocyte proliferation (EC3) could not be calculated but was estimated to be > 25% w/v (6250 micrograms/cm2). See Table 1.

Any other information on results incl. tables

Table:  Skin Sensitization Results for LLNA-965

Concentration of test substance (%w/v)

Number of lymph nodes assayed

Disintegrations per minute (dpm)

dpm per lymph node

Test: Control ratio (SI)

0 (vehicle only)

8

4857

607

N/A

0.5

8

4435

554

0.9

1

8

3646

456

0.8

2.5

8

4053

507

0.8

10

8

4236

530

0.9

25

8

6565

821

1.4

Applicant's summary and conclusion

Interpretation of results:
not sensitising
Remarks:
Migrated information
Conclusions:
Under the conditions of this test, the test article was not rated as a potential skin sensitizer.
Executive summary:

The test material was assessed for skin sensitizing potential using the mouse Local Lymph Node Assay. The material was applied as 0.5, 1, 2.5, 10 or 25% w/v preparations in 1:3 ethanol:diethylphthalate. The test material failed to produce a 3 -fold increase in lymphocyte proliferation and the EC3 value was estimated to be in excess of 6250 micrograms/cm^2.