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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:
weight of evidence
Study period:
19 Feb 2013 - 12 March 2013
Reliability:
1 (reliable without restriction)
Rationale for reliability incl. deficiencies:
other: GLP guideline study, for read-across justification refer to IUCLID section 13.

Data source

Reference
Reference Type:
study report
Title:
Unnamed
Year:
2013
Report Date:
2014

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:
EU Method B.42 (Skin Sensitisation: Local Lymph Node Assay)
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
Test material form:
other: liquid
Details on test material:
Please refer to confidential details on test material

In vivo test system

Test animals

Species:
mouse
Strain:
CBA
Sex:
female
Details on test animals and environmental conditions:
TEST ANIMALS
- Source: Harlan Laboratories B.V., AD Horst/Netherlands
- Age at study initiation: pre-test: 10 - 11 weeks (beginning of treatment); Main study: 9 - 10 weeks (beginning of treatment)
- Weight at study initiation: 20.7 +/- 0.9 g
- Housing: Makrolon Type II (pre-test) / III (main study), with wire mesh top; group housing; granulated soft wood bedding
- Diet (e.g. ad libitum): ad libitum
- Water (e.g. ad libitum): ad libitum
- Acclimation period: At least 5 days prior to the start of dosing under test conditions after health examination

ENVIRONMENTAL CONDITIONS
- Temperature (°C): 22 +/- 2
- Humidity (%): 45 - 65%
- Photoperiod (hrs dark / hrs light): 12h/12h

IN-LIFE DATES: From: 27 Feb 2013 To: 12 March 2013

Study design: in vivo (LLNA)

Vehicle:
acetone/olive oil (4:1 v/v)
Concentration:
0% (control); 10, 25 and 50% in acetone/olive oil (4:1 v/v)
No. of animals per dose:
5
Details on study design:
RANGE FINDING TESTS:

- Irritation: On day 3 the animal treated with 100% test item concentration showed an erythema of the ear skin (Score 1), increase in ear weight > 25%


MAIN STUDY
ANIMAL ASSIGNMENT AND TREATMENT
- Criteria used to consider a positive response: A test item is regarded as a sensitiser in the LLNA if the following criteria are fulfilled: First, that exposure to at least one concentration of the test item resulted in an incorporation of 3HTdR at least 3-fold or greater than that recorded in control mice, as indicated by the Stimulation Index. Second, that the data are compatible with a conventional dose response, although allowance must be made (especially at high topical concentrations) for either local toxicity or immunological suppression.

TREATMENT PREPARATION AND ADMINISTRATION:
The preparations were made freshly before each dosing occasion. The different test item concentrations were prepared individually. Each test group of mice was treated by (epidermal) topical application to the dorsal surface of each ear with test item concentrations of 10, 25, and 50% in acetone:olive oil (4+1, v/v). The application volume, 25 μL/ear/day, was spread over the entire dorsal surface (∅ ∼ 8 mm) of each ear once daily for three consecutive days. A further group of mice (control animals) was treated with an equivalent volume of the relevant vehicle alone (control animals).
Positive control substance(s):
hexyl cinnamic aldehyde (CAS No 101-86-0)
Statistics:
The mean values and standard deviations were calculated in the body weight tables, for the ear weights, the lymph node weights and lymph node cell count, and for the DPM values (group mean DPM ± standard deviation).
A statistical analysis was conducted on the DPM values, the ear weights, the lymph node weights and the lymph node cell count to assess whether the difference was statistically significant between the test item groups and negative control group. For all statistical calculations SigmaStat for Windows (Version 2.0) was used. A One-Way-Analysis-of-Variance was used as a statistical method. In case of significant results of the One-Way-ANOVA, multiple comparisons were performed with the Dunnett test. Statistical significance was set at the five per cent level (p < 0.05).

Results and discussion

Positive control results:
The periodic positive control experiment with α-Hexylcinnamaldehyde in acetone:olive oil (4+1 v/v) was performed using CBA/CaOlaHsd mice in October 2012. At the concentration of 25 %, an increase in cellularity and a stimulation index exceeding the threshold value of 3 (SI = 5.7) were noted. The study was therefore considered valid.

In vivo (LLNA)

Resultsopen allclose all
Parameter:
SI
Remarks on result:
other: Control Group: 1.00 Test Group (10 %): 0.84 Test Group (25 %): 2.08 Test Group (50 %): 3.70 Positive control group (25 % HCA): 5.7
Parameter:
other: disintegrations per minute (DPM)
Remarks on result:
other: Mean dpm per animal (2 lymph nodes): Control Group: 358.6 +/- 146.2 dpm Test Group (10 %): 301.0 +/- 96.2 dpm Test Group (25 %): 745.2 +/- 183.5 dpm Test Group (50 %): 1327.2 +/- 638.0 dpm Positive control group (25 % HCA): 3430.0 dpm

Any other information on results incl. tables

No deaths occurred during the study period.

No signs of systemic toxicity were observed during the study period.

The body weight of the animals, recorded prior to the first application and prior to treatment with 3HTdR, was within the range commonly recorded for animals of this strain and age.

A statistically significant increase in ear weights was not observed in any treated group in comparison to the vehicle control group. Furthermore, for BALB/c mice, a cutoff-value of 1.1 for the ear weight index was reported for a positive response regarding ear skin irritation. The index determined for the high dose group of 1.12 reached this threshold, indicating a marginal borderline positive response for ear skin irritation. But the index obtained did not exceed the threshold of 1.25 for excessive irritation stated in the OECD.

A statistically significant and biological relevant increase in lymph node weight was observed in the high dose group.

For the lymph node cell count, a statistically significant and biologically relevant increase was observed in the mid and high dose group in comparison to the vehicle control group. Furthermore, the cutoff-value of 1.55 for a positive response regarding the lymph node cell count index reported for BALB/c mice was exceeded in the high dose group (index of 1.8).

Applicant's summary and conclusion

Interpretation of results:
other: weakly sensitizing
Remarks:
Criteria used for interpretation of results: EU