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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:
From 20 Dec 2016 to 19 Jan 2017
Reliability:
1 (reliable without restriction)

Data source

Reference
Reference Type:
study report
Title:
Unnamed
Year:
2017

Materials and methods

Test guideline
Qualifier:
according to guideline
Guideline:
OECD Guideline 442B (Skin Sensitization: Local Lymph Node Assay: BrdU-ELISA)
Deviations:
no
GLP compliance:
yes (incl. QA statement)
Type of study:
mouse local lymph node assay (LLNA): BrdU-ELISA

Test material

1
Chemical structure
Reference substance name:
trans-(4-(methylamino)cyclohexyl)methanesulfonic acid
Cas Number:
2124221-12-9
Molecular formula:
C8H17NO3S
IUPAC Name:
trans-(4-(methylamino)cyclohexyl)methanesulfonic acid

In vivo test system

Test animals

Species:
mouse
Strain:
CBA:J
Sex:
female
Details on test animals and environmental conditions:
TEST ANIMALS
- Source: Jackson Laboratories (Bar Harbor, ME)
- Females (if applicable) nulliparous and non-pregnant: yes
- Microbiological status of animals, when known:
- Age at study initiation: The animals were born on 18 Oct 2016, ± 3 days.
- Weight at study initiation: The Day 1 body weight range for the preliminary dermal irritation screen animals was 18.3 - 21.1 grams.
- Housing: The animals were identified by cage notation and indelible tail marks. During the acclimation period the animals were housed two per cage in suspended wire-bottom cages; during the study the animals were housed one per cage. Bedding was placed beneath the cages and changed at least three times per week.
- Diet (e.g. ad libitum): Fresh PMI Rodent Chow (Diet No. 5001) and water were available ad libitum.
- Water (e.g. ad libitum): water were available ad libitum.
- Acclimation period: at least five days
- Indication of any skin lesions:

ENVIRONMENTAL CONDITIONS
- Temperature (°C):
- Humidity (%):
- Air changes (per hr):
- Photoperiod (hrs dark / hrs light): 12-hour light/dark cycle

Study design: in vivo (LLNA)

Vehicle:
dimethyl sulphoxide
Concentration:
10%, 25%, and 50% (w/v)
No. of animals per dose:
5 females
Details on study design:
PRE-SCREEN TESTS:
- Compound solubility: homogenous, dosable suspension was obtained in DMSO.
- Irritation: no
- Systemic toxicity: no
- Ear thickness measurements: Ear thickness measurements were performed on Day 1 prior to dosing, on Day 3 before the third test article application, and on Day 6 before euthanasia. None of the test article treatments resulted in increases in ear thickness of 25% or more, and therefore the test article was not considered irritating.
- Erythema scores: 0

MAIN STUDY:
The test article concentrations used in the main LLNA study were chosen such that the
maximum concentration tested was the highest doseable formulation of the test article in the vehicle, while avoiding both overt systemic toxicity and excessive local dermal irritation. Concentrations of 10%, 25%, and 50% (w/v) were chosen by the Study Director in consultation with the Sponsor.
Five groups of CBA/J mice (five animals per group) were treated by topical application of the test article concentrations, vehicle control or positive control in the same manner as in the screen.

ANIMAL ASSIGNMENT AND TREATMENT
- Criteria used to consider a positive response: A test article is considered to have a positive response if treatment results in a 1.6-fold or greater increase in the mean LNC proliferation (BrdU ELISA OD values) relative to that obtained for the vehicle control.
Positive control substance(s):
hexyl cinnamic aldehyde (CAS No 101-86-0)
Statistics:
For each test group, the individual animal SI values along with the mean group SI and standard deviation were calculated, and ANOVA followed by the Students’ t-Test was run to statistically compare each test article dose group to the vehicle control group. Although specified in the test guidelines, these calculations and results were not incorporated into the interpretation of the data. An SI value of 1.6 or more is the sole determinant for a positive sensitization response.

Results and discussion

In vivo (LLNA)

Resultsopen allclose all
Key result
Parameter:
SI
Value:
0.8
Test group / Remarks:
10% (w/v)
Key result
Parameter:
SI
Value:
0.7
Test group / Remarks:
25% (w/v)
Key result
Parameter:
SI
Value:
0.7
Test group / Remarks:
50% (w/v)
Cellular proliferation data / Observations:
Body Weights: Body weight changes were normal in the screen. In the main test, body weight loss was noted but were not significant (less than 2 g).
Mortality and Systemic Observations:
All animals survived the in-life phase of the study. Prior to the study start, all animals were observed to ensure that no skin lesions were present on the ears. All animals were observed once daily throughout the study for clinical signs, either of local irritation at the application site or systemic toxicity, and for mortality.
Erythema Scores: No test article treatment produced erythema.
Ear Thickness as a Measure of Dermal Irritation: None of the test item concentrations tested resulted in excessive dermal irritation.

Applicant's summary and conclusion

Interpretation of results:
GHS criteria not met
Conclusions:
Topical application of test article at 10%, 25%, and 50% (w/v) in DMSO resulted in SI values less than 1.6. Therefore, this test article is not a dermal sensitizer in the Local Lymph Node Assay.
Executive summary:

The study is performed according to OECD Guideline 442B using mice. Topical application of test article at 10%, 25%, and 50% (w/v) in DMSO resulted in SI values less than 1.6. Therefore, this test article is not a dermal sensitizer in the Local Lymph Node Assay.