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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
Study period:
24 Jan 2014 - 24 Feb 2014
Reliability:
1 (reliable without restriction)
Rationale for reliability incl. deficiencies:
guideline study

Data source

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

Materials and methods

Test guidelineopen allclose all
Qualifier:
according to
Guideline:
OECD Guideline 429 (Skin Sensitisation: Local Lymph Node Assay)
Version / remarks:
(adopted 22 Jul 2010)
Deviations:
no
Qualifier:
according to
Guideline:
EU Method B.42 (Skin Sensitisation: Local Lymph Node Assay)
Version / remarks:
(adopted 30 May 2008)
Deviations:
no
Qualifier:
according to
Guideline:
EPA OPPTS 870.2600 (Skin Sensitisation)
Version / remarks:
(adopted Mar 2003)
Deviations:
no
GLP compliance:
yes (incl. certificate)
Remarks:
Bayerisches Landesamt fuer Gesundheit und Lebensmittelsicherheit, Erlangen, Germany
Type of study:
mouse local lymph node assay (LLNA)

Test material

Reference
Name:
Unnamed
Type:
Constituent
Test material form:
solid

In vivo test system

Test animals

Species:
mouse
Strain:
other: CBA/CaOlaHsD
Sex:
female
Details on test animals and environmental conditions:
TEST ANIMALS
- Source: Harlan Laboratories GmbH, Venray, The Netherlands
- Age at study initiation: 9-10 weeks
- Housing: in groups of 5 in IVC cages, type II L, polysulphone cages on Altromin saw fibre bedding (lot no. 131113)
- Diet: Altromin 1324 maintenance diet for rats and mice (lot no. 0801), ad libitum
- Water: tap water, sulphur acidified to a pH value of approximately 2.8 (drinking water, municipal residue control, microbial control at regular intervals), ad libitum
- Acclimation period: at least 5 days

ENVIRONMENTAL CONDITIONS
- Temperature (°C): 22±3
- Humidity (%): 55±10
- Air changes (per hr): at least 10
- Photoperiod (hrs dark / hrs light): 12/12

Study design: in vivo (LLNA)

Vehicle:
dimethyl sulphoxide
Concentration:
17, 33 and 67% (w/v)
No. of animals per dose:
3 in prescreen test (2 in test group and 1 treated with vehicle alone as negative control)
5/group in main study
Details on study design:
RANGE FINDING TESTS:
- Compound solubility: DMSO was selected as vehicle due to the solubility properties of the test item. The maximum technically applicable concentration of the test item in DMSO was determined to be 67%.
- Irritation: No irritation was observed at the maximum technically feasible concentration of 67% test item in DMSO and after treatment with DMSO alone.
- Lymph node proliferation response: Not conducted in pre-screen test.

MAIN STUDY
ANIMAL ASSIGNMENT AND TREATMENT
- Name of test method: 3H-Methyl Thymidine (3HTdR) incorporation method
- Criteria used to consider a positive response: A substance is regarded as a "sensitiser" in the LLNA if at least one concentration of the test item results in a 3-fold or greater increase in 3HTdR incorporation into lymph node cells of the test group animals, relative to that recorded for the lymph nodes of control group animals (i.e. Stimulation index equal or greater than 3.0).

TREATMENT PREPARATION AND ADMINISTRATION:
Each mouse was treated by topical application of 25 µL of the selected solution to the entire dorsal surface of each ear. Topical applications were performed once daily over three consecutive days.
Five days after the first topical application all mice were dosed with 20 µCi 3HTdR by intravenous injection (Tail vein) of 250 µL of 3HTdR, diluted to a working concentration of 80 µCi/mL.
Approximately 5 h after the injection of 3HTdR all mice were sacrificed. The draining auricular lymph nodes were excised, individually pooled for each animal (2 lymph node per animal) and collected in phosphated buffered saline (PBS). A single cell suspension of pooled lymph node cells was prepared by gentle mechanical disaggregation through polyamide gauze (200 mesh size). After washing the gauze with PBS the cell suspension was pelleted in a centrifuge. The supernatant was discarded and the pellets were resuspended with PBS: The washing procedure was repeated. After the final wash each pellet was resuspended in approximately 1 mL 5% trichloroacetic acid (TCA) at approximately 4°C for approximately 18 h for precipitation of macromolecules. Each precipitate was once washed again, resuspended in 1 mL 5% TCA and 7 mL scintillation fluid was added. Then this solution was transferred into scintillation vials and stored at room temperature overnight.
3HTdR incorporation was measured in a ß-counter and expressed as the number of disintegrations per minute (DPM). Similarly, background 3HTdR levels were also measured (5% TCA). Determination of radioactivity was performed individually for each animal.
Positive control substance(s):
other: p-phenylenediamine (CAS 106-50-3, Sigma, purity >98%, lot no. SLBC7171V), 1% in DMSO

Results and discussion

Positive control results:
The recent reliability check was performed in Nov 2013. The DPM/node were 1891.9±387.6 for the negative control animals and 18051.7±1056.2 for the positive control animals. SI of the positive control animals was 9.5±0.6. The sensitivity of the test system was thus confirmed.

In vivo (LLNA)

Resultsopen allclose all
Key result
Parameter:
SI
Value:
5
Variability:
± 1.4
Test group / Remarks:
17% solution
Key result
Parameter:
SI
Value:
6
Variability:
± 0.6
Test group / Remarks:
33% solution
Key result
Parameter:
SI
Value:
8.9
Variability:
± 3.2
Test group / Remarks:
67% solution
Key result
Parameter:
EC3
Value:
4.51
Parameter:
other: disintegrations per minute (DPM)/node
Value:
1 539.4
Variability:
± 353.1
Test group / Remarks:
negative control
Parameter:
other: disintegrations per minute (DPM)/node
Value:
7 706.9
Variability:
± 2165.6
Test group / Remarks:
17% solution
Parameter:
other: disintegrations per minute (DPM)/node
Value:
9 204.6
Variability:
± 898.8
Test group / Remarks:
33% solution
Parameter:
other: disintegrations per minute (DPM)/node
Value:
13 683.1
Variability:
± 9886.7
Test group / Remarks:
67% solution

Any other information on results incl. tables

Pre-screen test

Neither signs of systemic toxicity nor signs of irritation at any application site could be detected in any animal. One animal showed weight loss of 4 g. All other animals showed the expected weight development, which includes a weight loss of up to 2 g throughout the duration of the pre-screen test.

Main study

All animals survived throughot the study period. On Day 6, one animal of the 33% group showed bodyweight loss, hypothermia, dehydration, piloerection and lymph nodes with a small size. All other test group animals showed enlarged lymph nodes, and their body weights developed as expected. Eschar was observed in all animals of the test groups on Day 6. As only one animal of the mid dose group (33%) showed clinical signs, a clear test item relation cannot be concluded.

Applicant's summary and conclusion

Interpretation of results:
Category 1B (indication of skin sensitising potential) based on GHS criteria
Conclusions:
CLP: Cat 1B, H317