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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:
The study was conducted between 04 November 2016 and 29 November 2016
Reliability:
1 (reliable without restriction)
Rationale for reliability incl. deficiencies:
other: The study is considered to be a reliability 1 as it has been conducted according to OECD Test Guideline 429 using the Skin Sensitisation: Local Lymph Node Assay method and in compliance with GLP.

Data source

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

Materials and methods

Test guidelineopen allclose all
Qualifier:
according to guideline
Guideline:
OECD Guideline 429 (Skin Sensitisation: Local Lymph Node Assay)
Version / remarks:
22 July 2010
Deviations:
no
Qualifier:
according to guideline
Guideline:
EU Method B.42 (Skin Sensitisation: Local Lymph Node Assay)
Version / remarks:
EC No. 440/2008
Deviations:
no
GLP compliance:
yes (incl. QA statement)
Type of study:
mouse local lymph node assay (LLNA)

Test material

Constituent 1
Chemical structure
Reference substance name:
1-(2,4-dimethylcyclohex-3-en-1-yl)propan-1-ol
EC Number:
944-553-4
Cas Number:
1632042-40-0
Molecular formula:
C11H20O
IUPAC Name:
1-(2,4-dimethylcyclohex-3-en-1-yl)propan-1-ol
Test material form:
solid
Details on test material:
- Substance name as cited in test report: FRET 11-0571
- Phystical state: white solid
- Storage conditions: ambient temperature (15-25 °C)
Specific details on test material used for the study:
SOURCE OF TEST MATERIAL
- Source and lot/batch No.of test material: Sponsor Batch No. PDJ378-75
- Expiration date of the lot/batch: 01 June 2018
- Purity test date: 11 July 2016
- Purity: 96%
- Appearance: White solid
- Storage condition of test material: room temperature 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:

Female CBA/Ca (CBA/CaOlaHsd) strain mice were supplied by Envigo RMS B.V., Inc., Horst, The Netherlands. On receipt the animals were randomly allocated to cages. The animals were nulliparous and non pregnant. After an acclimatisation period of at least five days the animals were selected at random and given a number unique within the study by indelible ink marking on the tail and a number written on a cage card. At the start of the study the animals were in the weight range of 15 to 23 g, and were eight to twelve weeks old.

The animals were individually housed in suspended solid floor polypropylene cages furnished with softwood woodflakes. Free access to mains tap water and food (2014C Teklad Global Rodent diet supplied byEnvigo RMS (UK) Limited, Oxon, UK) was allowed throughout the study.
The temperature and relative humidity were controlled to remain within target ranges of xx toxx°C and xx toxx %, respectively. Any occasional deviations from these targets were considered not to have affected the purpose or integrity of the study. The rate of air exchange was approximately xxx changes per hour and the lighting was controlled by a time switch to give twelve hours continuous light and twelve hours darkness.

The animals were provided with environmental enrichment items which were considered not to contain any contaminant of a level that might have affected the purpose or integrity of the study.

Study design: in vivo (LLNA)

Vehicle:
acetone/olive oil (4:1 v/v)
Concentration:
Preliminary Test:
Test item at a concentration of 50% w/w in acetone/olive oil 4:1

Main Test:
Test item at concentrations of 50%, 25% or 10% w/w in acetone/olive oil 4:1.
No. of animals per dose:
Preliminary test : one mouse

Main Test: 5 mice per concentration
Details on study design:
Dissiminated (delete when editing)

Preliminary Screening Test
Using available information regarding the 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 50% w/w in acetone/olive oil 4:1, 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 irritation was scored daily according to the erythema scores. Any clinical signs of toxicity, if present, were also recorded. The bodyweight 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 Days 1 to 3 and Days 1 to 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 sensitisation.

Main Test
Test Item Administration
Groups of five mice were treated with the undiluted test item or the test item at concentrations of 50 % or 25 % v/v in acetone/olive oil 4:1. The preliminary screening test suggested that the test item would not produce systemic toxicity or excessive local 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 five mice received the vehicle alone in the same manner.

The positive control animals were similarly treated to the test animals except that 25 µl of the positive control item, α Hexylcinnamaldehyde, 97.3 %, at a concentration of 25 % v/v in acetone/olive oil 4:1 was applied to the dorsal surface of each ear.

3H-Methyl Thymidine Administration
Five days following the first topical application of the test item, vehicle control or positive control item (Day 6) all mice were injected via the tail vein with 250 µl of phosphate buffered saline (PBS) containing 3H methyl thymidine (3HTdR:80µCi/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.

Bodyweights: The bodyweight 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. For each individual animal of each group the draining auricular lymph nodes were excised and processed. For each individual animal 1 ml of PBS was added to the lymph nodes.

Preparation of Single Cell Suspension: A single cell suspension of the lymph node cells for each individual animal 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 labelled with the project number and dose concentration. The lymph node cells 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 lymph node cells were pelleted at 1400 rpm (approximately 190 g) for ten minutes. The pellet was resuspended in 10 ml of PBS and re-pelleted. To precipitate out the radioactive material, the pellet was resuspended in 3 ml of 5% Trichloroacetic acid (TCA).

Determination of 3HTdR Incorporation: After approximately eighteen hours incubation at approximately 4°C, the precipitates were recovered by centrifugation at 2100 rpm (approximately 450 g) for ten minutes, resuspended in 1 ml of TCA and transferred to 10 ml of scintillation fluid. 3HTdR incorporation was measured by beta scintillation counting. The "Poly QTM" vials containing the samples and scintillation fluid were placed in the sample changer of the scintillator and left for approximately twenty 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 twenty 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).
3
Data Evaluation
The proliferation response of lymph node cells was expressed as the number of radioactive disintegrations per minute per animal 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".
The results were also interpreted according to Regulation (EC) No. 1272/2008, relating to the Classification, Labelling and Packaging of Substances and Mixtures and the Globally Harmonized Classification System.
Positive control substance(s):
hexyl cinnamic aldehyde (CAS No 101-86-0)
Statistics:
Data was processed to give group mean values for disintegrations per minute and standard deviations where appropriate. Individual and group mean disintegrations per minute values were assessed for dose response relationships. Data was first assessed for suitability by analysis of normality and homogeneity of variance. If the assumptions that the data are both normally distributed and has homogeneity of variances, then parametric one way analysis of variance (ANOVA) and Dunnett’s multiple comparison procedure were used to determine statistical significance. If the assumptions were not met, non parametric Kruskal Wallis Rank Sum and Mann Whitney U test procedures were used.
Probability values (p) are presented as follows:
P<0.001 ***
P<0.01 **
P<0.05 *
P>0.05 (not significant)

Results and discussion

Positive control results:
The positive control item, α-Hexylcinnamaldehyde, 97.3%, gave a Stimulation Index of greater than 3 when tested at a concentration of 25 % v/v in acetone/olive oil 4:1.

In vivo (LLNA)

Results
Key result
Parameter:
SI
Remarks on result:
other: The following SI values were derived at 10, 25 and 50%:1.35, 1.46 and 1.17, respectively.

Any other information on results incl. tables

Preliminary screening test:

No signs of systemic toxicity or excessive 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 50%, 25% and 10% w/w in acetone/olive oil 4:1

Main Test

Estimation of the Proliferative Response of Lymph Node Cells

The radioactive disintegrations per minute per lymph node and the stimulation index are given in Appendix 4.

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:

 Treatment Group  Concnetration  Simulation Index  Result
 Test Item

 10% w/w in acetone/olive oil 4:1

 1.35

 Negative

 

 25% w/w in acetone/olive oil 4:1

 1.46

 Negative

 

50% w/w in acetone/olive oil 4:1

 1.17

 Negative

 Positive Control Item

25% w/w in acetone/olive oil 4:1

 5.68

 Positive

Clinical Observations and Mortality Data

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

Body Weight

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.

Applicant's summary and conclusion

Interpretation of results:
other: considered to be a non-sensitizer under the conditions of the test
Conclusions:

The test item was considered not to be a sensitiser under the conditions of the test .
Executive summary:

The skin sensitisation potential of the test substance has been tested according to OECD TG 429: Local Lymph Node Assay" method. At 10, 25 and 50% the substance showed SI values of 1.35, 1.46 and 1.17 , respectively.