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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:
2016
Reliability:
1 (reliable without restriction)
Rationale for reliability incl. deficiencies:
guideline study
Justification for type of information:
None

Data source

Reference
Reference Type:
study report
Title:
Unnamed
Year:
2016
Report Date:
2016

Materials and methods

Test guidelineopen allclose all
Qualifier:
according to
Guideline:
OECD Guideline 429 (Skin Sensitisation: Local Lymph Node Assay)
Version / remarks:
22 July 2010
Deviations:
no
Qualifier:
according to
Guideline:
EU Method B.42 (Skin Sensitisation: Local Lymph Node Assay)
Version / remarks:
2008
Deviations:
no
Qualifier:
according to
Guideline:
EPA OPPTS 870.2600 (Skin Sensitisation)
Version / remarks:
2003
Deviations:
no
Qualifier:
according to
Guideline:
other: Japanese Ministry of Agriculture, Forestry and Fisheries (JMAFF), Testing Guidelines for Toxicology Studies, 12 NohSan No. 8147, amended 10 December 2002
Version / remarks:
10 December 2002
Deviations:
no
Principles of method if other than guideline:
None
GLP compliance:
yes
Type of study:
mouse local lymph node assay (LLNA)

Test material

Reference
Name:
Unnamed
Test material form:
solid
Specific details on test material used for the study:
STABILITY AND STORAGE CONDITIONS OF TEST MATERIAL
- Storage condition of test material: Approximately -20”C in the dark

In vivo test system

Test animals

Species:
mouse
Strain:
CBA/Ca
Remarks:
CBA/CaOlaHsd
Sex:
female
Details on test animals and environmental conditions:
TEST ANIMALS
- Source: Envigo RMS B.V., Inc., Horst, The Netherlands
- Females (if applicable) nulliparous and non-pregnant: yes

- Age at study initiation: 8-12 weeks
- Weight at study initiation: 15-23 g
- Housing: suspended solid floor polypropylene cages furnished with softwood woodflakes
- Diet (e.g. ad libitum): ad libitum
- Water (e.g. ad libitum): ad libitum
- Acclimation period: >5 days
- Indication of any skin lesions: no

ENVIRONMENTAL CONDITIONS
- Temperature (°C): 19-25”C
- Humidity (%): 30-70%
- Air changes (per hr): >15
- Photoperiod (hrs dark / hrs light): 12/12
- IN-LIFE DATES: From: 06 June 2016 To: 19 July 2016

Study design: in vivo (LLNA)

Vehicle:
other: 1% pluronic L92 in distilled water
Concentration:
Preliminary Screening Test = 25% w/w in 1% pluronic L92 in distilled water

Main Test = 25%, 10% or 5% w/w in 1% pluronic L92 in distilled water
No. of animals per dose:
Preliminary Screening Test = 1 mouse

Main Test = 4 mice per group
Details on study design:
Preliminary Screening Test
As no toxicological information was available regarding the systemic toxicity/irritancy potential of the test item, a preliminary screening test was performed using one mouse. The mouse was treated by daily application of 25 µL of the test item at a concentration of 25% w/w in 1% pluronic L92 in distilled water, to the dorsal surface of each ear for three consecutive days (Days 1, 2, 3). The mouse was observed twice daily on Days 1, 2 and 3 and once daily on Days 4, 5 and 6. Local skin irritation was scored daily according to the scale included below. Any clinical signs of toxicity, if present, were also recorded. The body weight was recorded on Day 1 (prior to dosing) and on Day 6.
The thickness of each ear was measured using a Mitutoyo 547 300S gauge (Mitutoyo Corporation), pre dose on Day 1, post dose on Day 3 and on Day 6. Any changes in the ear thickness were noted. Mean ear thickness changes were calculated between time periods Days 1 and 3 and Days 1 and 6. A mean ear thickness increase of equal to or greater than 25% was considered to indicate excessive irritation and limited biological relevance to the endpoint of sensitization.

Main Test
Test Item Administration
Groups of four mice were treated with the test item at concentrations of 25%, 10% or 5% w/w in 1% pluronic L92 in distilled water. The preliminary screening test suggested that the test item would not produce systemic toxicity or excessive local skin irritation at the highest suitable concentration. The mice were treated by daily application of 25 µL of the appropriate concentration of the test item to the dorsal surface of each ear for three consecutive days (Days 1, 2, 3). The test item formulation was administered using an automatic micropipette and spread over the dorsal surface of the ear using the tip of the pipette.
A further group of four mice received the vehicle alone in the same manner.

3H-Methyl Thymidine Administration
Five days following the first topical application of the test item or vehicle (Day 6) all mice were injected via the tail vein with 250 µL of phosphate buffered saline (PBS) containing 3H methyl thymidine (3HTdR: 80 µCi/mL, specific activity 2.0 Ci/mmoL, ARC UK Ltd) giving a total of 20 µCi to each mouse.

Observations
Clinical Observations: All animals were observed twice daily on Days 1, 2 and 3 and on a daily basis on Days 4, 5 and 6. Any signs of toxicity or signs of ill health during the test were recorded.
Body Weights: The body weight of each mouse was recorded on Day 1 (prior to dosing) and Day 6 (prior to termination).

Terminal Procedures
Termination: Five hours following the administration of 3HTdR all mice were killed by carbon dioxide asphyxiation followed by cervical separation. The draining auricular lymph nodes from the four mice were excised and pooled for each experimental group. For each group 1 mL of PBS was added to the pooled lymph nodes.

Preparation of Single Cell Suspension: A single cell suspension of pooled lymph node cells was prepared by gentle mechanical disaggregation through a 200 mesh stainless steel gauze. The lymph node cells were rinsed through the gauze with 4 mL of PBS into a petri dish labeled with the study number and dose concentration. The lymph node cell suspension was transferred to a centrifuge tube. The petri dish was washed with an additional 5 mL of PBS to remove all remaining lymph node cells and these were added to the centrifuge tube. The pooled lymph node cells were pelleted at 1400 rpm (approximately 190 g) for 10 minutes.
The pellet was re suspended in 10 mL of PBS and re pelleted. To precipitate out the radioactive material, the pellet was re suspended in 3 mL of 5% Trichloroacetic acid (TCA).

Determination of 3HTdR Incorporation:
After approximately 18 hours incubation at approximately 4 C, the precipitates were recovered by centrifugation at 2100 rpm (approximately 450 g) for 10 minutes, re suspended in 1 mL of TCA and transferred to 10 mL of scintillation fluid. 3HTdR incorporation was measured by scintillation counting. The "Poly Q™" vials containing the samples and scintillation fluid were placed in the sample changer of the scintillator and left to stand in darkness for approximately 20 minutes. The purpose of this period of time in darkness was to reduce the risk of luminescence, which has been shown to affect the reliability of the results. After approximately 20 minutes, the vials were shaken vigorously. The number of radioactive disintegrations per minute was then measured using the Beckman LS6500 scintillation system (Beckman Instruments Inc, Fullerton, CA, USA).

Data Evaluation
The proliferation response of lymph node cells was expressed as the number of radioactive disintegrations per minute per lymph node (disintegrations per minute/node) and as the ratio of 3HTdR incorporation into lymph node cells of test nodes relative to that recorded for the control nodes (Stimulation Index).
The test item will be regarded as a sensitizer if at least one concentration of the test item results in a threefold or greater increase in 3HTdR incorporation compared to control values. Any test item failing to produce a threefold or greater increase in 3HTdR incorporation will be classified as a "non sensitizer".
Positive control substance(s):
hexyl cinnamic aldehyde (CAS No 101-86-0)
Statistics:
None

Results and discussion

Positive control results:
α Hexylcinnamaldehyde, tech., 85% was considered to be a sensitizer under the conditions of the test with a Stimulation Index of 4.47

In vivo (LLNA)

Resultsopen allclose all
Key result
Parameter:
SI
Value:
1.25
Test group / Remarks:
5% w/w
Remarks on result:
other: Negative
Key result
Parameter:
SI
Value:
1.65
Test group / Remarks:
10% w/w
Remarks on result:
other: Negative
Key result
Parameter:
SI
Value:
2.33
Test group / Remarks:
25% w/w
Remarks on result:
other: Negative
Cellular proliferation data / Observations:
Preliminary Screening Test
No signs of systemic toxicity, visual local skin irritation or irritation indicated by an equal to or greater than 25% increase in mean ear thickness were noted.
Based on this information the dose levels selected for the main test were 25%, 10% and 5% w/w in 1% pluronic L92 in distilled water.

Main Test
Estimation of the Proliferative Response of Lymph Node Cells
The Stimulation Index expressed as the mean radioactive incorporation for each treatment group divided by the mean radioactive incorporation of the vehicle control group are as follows:

Concentration (%w/w) in
1% pluronic L92 in distilled water Stimulation Index Result
5 1.25 Negative
10 1.65 Negative
25 2.33 Negative

There were no deaths. No signs of systemic toxicity were noted in the test or control animals during the test.

Body weight change of the test animals between Day 1 and Day 6 was comparable to that observed in the corresponding control group animals over the same period.

Any other information on results incl. tables

None

Applicant's summary and conclusion

Interpretation of results:
GHS criteria not met
Conclusions:
The test item was considered to be a non-sensitizer under the conditions of the test.
Executive summary:

A study was performed to assess the skin sensitization potential of the test item in the CBA/Ca strain mouse following topical application to the dorsal surface of the ear.

Methods

Following a preliminary screening test in which no clinical signs of toxicity were noted at a concentration of 25% w/w, this concentration was selected as the highest dose investigated in the main test of the Local Lymph Node Assay. Three groups, each of four animals, were treated with 50 µL (25 µL per ear) of the test item as a solution in 1% pluronic L92 in distilled water at concentrations of 25%, 10% or 5% w/w. A further group of four animals was treated with 1% pluronic L92 in distilled water alone.

Results

The Stimulation Index expressed as the mean radioactive incorporation for each treatment group divided by the mean radioactive incorporation of the vehicle control group are as follows:

 Concentration (%w/w) in 1% pluronic L92 in distilled water  Stimulation Index  Result
 5  1.25  Negative
 10  1.65  Negative
 25  2.33  Negative

Conclusion

The test item was considered to be a non-sensitizer under the conditions of the test. The test item does not meet the criteria for classification according to the Globally Harmonized Classification System.