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Skin sensitisation

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Administrative data

skin sensitisation: in vivo (LLNA)
Type of information:
experimental study
Adequacy of study:
key study
1 (reliable without restriction)
Rationale for reliability incl. deficiencies:
other: GLP guideline study

Data source

Reference Type:
study report
Report date:

Materials and methods

Test guideline
according to guideline
OECD Guideline 429 (Skin Sensitisation: Local Lymph Node Assay)
GLP compliance:
yes (incl. QA statement)
Type of study:
mouse local lymph node assay (LLNA)

Test material

Constituent 1
Chemical structure
Reference substance name:
4-nitrotoluene-2-sulphonic acid
EC Number:
EC Name:
4-nitrotoluene-2-sulphonic acid
Cas Number:
Molecular formula:
2-methyl-5-nitrobenzenesulfonic acid
Details on test material:
- Name of test material (as cited in study report):4-Nitrotoluene-2-sulphonic acid
- Analytical purity: 84.2 %
- Lot/batch No.: 090330

In vivo test system

Test animals

Details on test animals and environmental conditions:
- Source: Charles River Laboratories GmbH, Sulzfeld
- Age at study initiation: 8 - 12 weeks
- Weight at study initiation: 18.0 - 21.6 g
- Housing: single housed
- Diet (e.g. ad libitum): ad libitum
- Water (e.g. ad libitum): ad libitum
- Acclimation period: 7 days

- Temperature (°C): 20 - 24 °C
- Humidity (%): 30 - 70%
- Photoperiod (hrs dark / hrs light): 12/12

Study design: in vivo (LLNA)

propylene glycol
3, 10, 40 %
No. of animals per dose:
Details on study design:
Groups of 5 female CBA/J mice each were treated with 3%, 10% and 40% w/w preparations of the test substance in propylene glycol or with the vehicle alone. The 40% preparation was the maximum technically applicable concentration. The study used 3 test groups and 1 control group. Each test animal was applied with 25 µL per ear of the respective test-substance preparation to the dorsum of both ears for three consecutive days. The control group was treated with 25 µL per ear of the vehicle alone. Three days after the last application the mice were injected intravenously with 20 µCi of 3H-thymidine in 250 µL of sterile saline into a tail vein. About 5 hours after the 3H-thymidine injection, the mice were sacrificed and the auricular lymph nodes were removed. The weights of each animal’s pooled lymph nodes were determined. Thereafter lymph nodes were pooled group wise and further evaluated by measuring their cellular content and 3H-thymidine incorporation into the lymph node cells (indicators of cell proliferation). Moreover, a defined area with a diameter of 0.8 cm was punched out of the apical part of each ear and for each test group the weight of the pooled punches was determined in order to obtain an indication of possible skin irritation.
Positive control substance(s):
other: positive control was not included in this study

Results and discussion

Any other information on results incl. tables

When applied as 40% preparation in propylene glycol, the test substance induced a biologically relevant response (increase to 1.5 fold or above of control value = stimulation index (SI) ≥ 1.5) in the auricular lymph node cell counts. There was a relevant increase in lymph node weights, as well. Concomitantly, the increase of ³H-thymidine incorporation into the cells was biologically relevant (increase above the cut off stimulation index of 3) at this concentration.

The test-substance preparations did not cause any increase in ear weights.

The threshold concentration for sensitization induction was > 10% < 40%. The estimated concentration that leads to the SI of 1.5 for cell count (EC1.5) and the estimated concentrations that leads to the SI of 3.0 for ³H-thymidine incorporation (EC 3) was calculated by linear regression from the results of the 10% and 49% concentrations to be 16.4% and 26.2%, respectively.

Thus it is concluded that 4-Nitrotoluene-2-sulphonic acid shows a skin sensitizing effect in the Murine Local Lymph Node Assay under the test conditions chosen.

Applicant's summary and conclusion

Interpretation of results:
Migrated information