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Description of key information

Key value for chemical safety assessment

Skin sensitisation

Link to relevant study records
Reference
Endpoint:
skin sensitisation: in vivo (LLNA)
Type of information:
experimental study
Adequacy of study:
key study
Reliability:
1 (reliable without restriction)
Rationale for reliability incl. deficiencies:
other: Standard GLP study performed according to the OECD Guideline (429).
Qualifier:
according to
Guideline:
OECD Guideline 429 (Skin Sensitisation: Local Lymph Node Assay)
Deviations:
no
GLP compliance:
yes (incl. certificate)
Type of study:
mouse local lymph node assay (LLNA)
Species:
mouse
Strain:
other: CBA/CaOlaHsD
Sex:
female
Details on test animals and environmental conditions:
TEST ANIMALS
- Source: Harlan Winkelmann, 33178 Borchen, Germany
- Age at study initiation: 8-9 weeks
- Housing: full barrier in an air-conditioned room
- Diet: ad libitum, Altromin 1234
- Water: ad libitum, tap water sulphur acidified to a pH value of approx. 2.8
- 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

Vehicle:
acetone/olive oil (4:1 v/v)
Concentration:
12.5, 25 and 50% (w/v) in vehicle
No. of animals per dose:
5
Details on study design:
RANGE FINDING TESTS:
- Compound solubility: a solubility test was carried out, that showed 50% test substance in vehicle was the max possible concentration to be applied.
- Irritation:the animals were observed for local irritation at the application site. No signs of dermal irritation were observed.
- Lymph node proliferation response: no assessment

MAIN STUDY
ANIMAL ASSIGNMENT AND TREATMENT
- Criteria used to consider a positive response: ratios of 3H-methyl thymidine incorporation into lymph node of test group animals relative to that for control animals (Stimulation index)≥ 3 would be characterized as a positive response. The proliferative response was expressed as the number of radioactive disintegrations per minute per lymph node (DPM/NODE).

TREATMENT PREPARATION AND ADMINISTRATION: 25 µl of the test substance in acetone/olive oil 4:1 was applied on the entire doral ear area of each animal. The application was repeated daily, for three consecutive days. Five days after the 1st application 250 µL 20 µCi 3H-methyl thymidine was injected intrevenously to all mice (diluted concentration: 80 µCi/mL). All animals were sacrificed five hours after the aforementioned injection. The draining ear lymph nodes were excised into PBS and single cell suspension of lymphocyte was isolated. Cells were precipitated with 5% trichloroacetic acid at 4 °C for 18 hours.The radioactivity was measured in a ß-counter.



Positive control substance(s):
other: phenylenediamine
Statistics:
No
Parameter:
SI
Remarks on result:
other: 1.8, 1.7 and 1.9 for the concentrations of 12.5, 25 and 50%, respectively Positive control: 10.7
Parameter:
other: disintegrations per minute (DPM)
Remarks on result:
other: negative control: 552.1 ± 58.8, positive control: 9563.2 ± 756.2 test group: 1002.1 ± 328.2, 936.4± 22.5, 1048.1 ± 155.5

No effects were observed on the body weights and the lymph node weights of the animals tested with titanium carbide. No other signs of toxicity were seen in any of the animals.

Table 1: Mean weight of lymph nodes.

Group

Mean of test group

12.5% TiC in vehicle

3.2

25% TiC in vehicle

3.0

50% TiC in vehicle

3.3

Negative control

2.8

Interpretation of results:
not sensitising
Remarks:
Migrated information Criteria used for interpretation of results: EU
Conclusions:
Titanium carbide is not sensitizing to the mouse skin under the conditions of this LLNA study.
Executive summary:

In this dermal sensitization study with titanium carbide in acetone/olive oil 4:1 (v/v), young adult female CBA/CaOlaHsD mice were tested using the Local Lymph Node Assay (LLNA). 25 µl of the test substance in solvent were applied on the entire dorsal ear surface of each animal. The following concentrations were used: 12.5, 25 and 50%. Acetone/olive oil 4:1 was used as negative control. Phenylenediamine was tested as a positive control in a prior assay. The application was repeated daily for three consecutive days. The doses applied were selected based on a pre-screening assay. Five days after the 1st application 250 µL 20 µCi 3H-methyl thymidine was injected intravenously to all mice (diluted concentration: 80 µCi/mL). All animals were sacrificed five hours after the aforementioned injection. The draining ear lymph nodes were excised into PBS and single cell suspension of lymphocyte was isolated. Cells were precipitated with 5% trichloroacetic acid at 4 °C for 18 hours.The radioactivity was measured in a ß-counter.

Stimulation indices (ratio of 3H-methyl thymidine incorporation into lymph node of test animals relative to that for control animals)≥ 3 were considered a positive response. The results revealed the following SI: 1.8, 1.7 and 1.9 for the concentrations of 12.5, 25 and 50%, respectively. No signs of toxicity were detected in any of the treated animals. In this study, Titanimum carbide is not a dermal sensitizer.

Endpoint conclusion
Endpoint conclusion:
no adverse effect observed (not sensitising)
Additional information:

Titanium carbide in acetone/olive oil 4:1 (v/v) was tested in 5 young adult females per dose according to OECD 429 (LLNA). 25 µl of the test substance in solvent were applied on the entire dorsal ear surface of each animal at a concentration of 12.5, 25 and 50%. Phenylenediamine was tested as a positive control.

Stimulation indices (SI) (ratio of 3H-methyl thymidine incorporation into lymph node of test animals relative to that for control animals) ≥ 3 were considered a positive response. The results revealed SIs of 1.8, 1.7 and 1.9 for 12.5, 25 and 50%, respectively. No signs of toxicity were detected in any of the treated animals. In this study, Titanium carbide is not a dermal sensitizer.


Migrated from Short description of key information:
Local Lymph Node Assay

Justification for selection of skin sensitisation endpoint:
GLP Guideline study

Respiratory sensitisation

Endpoint conclusion
Endpoint conclusion:
no study available

Justification for classification or non-classification

Titanium carbide is not a dermal sensitizer in a valid OECD 429 assay (LLNA).