[No public or meaningful name is available]

Skin sensitisation

Administrative data

Endpoint:

skin sensitisation: in vivo (LLNA)

Type of information:

experimental study

Adequacy of study:

key study

Study period:

July 14 - September 3, 2014

Reliability:

1 (reliable without restriction)

Rationale for reliability incl. deficiencies:

guideline study

Data source

Reference

Reference Type:

study report

Title:

Unnamed

Year:

2014

Report date:

2014

Materials and methods

Test guideline

Qualifier:

according to guideline

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

Test material information

Constituent 1

Reference substance name:

6-Hydroxy-2,6-dimethylheptan-1-al

Cas Number:

62439-42-3

Molecular formula:

C9H18O2

IUPAC Name:

6-Hydroxy-2,6-dimethylheptan-1-al

Test material form:

liquid

In vivo test system

Test animals

Species:

mouse

Strain:

CBA/Ca

Sex:

female

Details on test animals and environmental conditions:

TEST ANIMALS
- Source: Harlan Laboratories UK Ltd., Oxon, UK
- 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
- Diet (e.g. ad libitum): 2014C Teklad Global Rodent Diet, ad libitum
- Water (e.g. ad libitum): tap water, ad libitum
- Acclimation period: at least 5 days
- Indication of any skin lesions:

ENVIRONMENTAL CONDITIONS
- Temperature (°C): 19-25 degrees C
- Humidity (%): 30-70%
- Air changes (per hr): 15
- Photoperiod (hrs dark / hrs light): 12/12
- IN-LIFE DATES: From: July 16, 2014 To: August 13, 2014

Study design: in vivo (LLNA)

Vehicle:

other: Ethanol/diethylphthalate 1:3

Concentration:

50% v/v in ethanol/diethylphthalate 1:3
25% v/v in ethanol/diethylphthalate 1:3
100%

No. of animals per dose:

5

Details on study design:

PRE-SCREEN TESTS:
- Irritation: No signs of irritation were noted
- Systemic toxicity: No signs of systemic toxicity were noted
- Ear thickness measurements: No ear thickness increase of greater than 25% was noted
- Erythema scores: 0

MAIN STUDY

ANIMAL ASSIGNMENT AND TREATMENT
- Criteria used to consider a positive response: Threefold or greater increase in 3HTdR incorporation.

TREATMENT PREPARATION AND ADMINISTRATION: Test formulations were made within 2 hours of being applied. Daily application of 25 uL of test solution on the dorsal surface of each ear for three consecutive days.

Positive control substance(s):

hexyl cinnamic aldehyde (CAS No 101-86-0)

Statistics:

Dose response relationships determined by analysis of homogeneity of variance followed by ANOVA. Significant results from ANOVA were analyzed by pairwise comparisons. Dunnett's Multiple Comparison test was used for homogenous datasets, and Dunnett's T3 Multiple Comparison Method was used for non-homogenous datasets.

Results and discussion

Positive control results:

Stimulation index: 15.91

In vivo (LLNA)

Results

Results 1

Key result

Parameter:

SI

Value:

5.62

Test group / Remarks:

100% concentration

Results 2

Key result

Parameter:

SI

Value:

5.98

Test group / Remarks:

50% concentration

Results 3

Key result

Parameter:

SI

Value:

2.7

Test group / Remarks:

25% concentration

Results 4

Key result

Parameter:

EC3

Value:

27.29

Test group / Remarks:

Based on 25%, 50%, and 100% concentrations

Cellular proliferation data / Observations:

DETAILS ON STIMULATION INDEX CALCULATION
The stimulation index was calculated by determining the mean radioactive incorporation for each test group, and dividing this by the mean radioactive incorporation for the vehicle control group.

EC3 CALCULATION
EC3= c + [[(3-d)/(b-d)] x (a-c)] where a = 50, b = 5.98, c = 25, and d = 2.70

CLINICAL OBSERVATIONS: No adverse clinical signs were observed.

BODY WEIGHTS: Body weight changes in the test groups were similar to the vehicle control group.

SIGNS OF TOXICITY (including dermal irritation at the site of administration, if any, e.g. increased ear thickness).
No signs of systemic toxicity were observed.

Any other information on results incl. tables

Disintegrations per minute

Treatment Group	Animal Number	Disintegrations per Minute
Vehicle	1-1	1747.26
Vehicle	1-2	2648.27
Vehicle	1-3	653.98
Vehicle	1-4	897.54
Vehicle	1-5	1023.14
Mean dpm/Animal		1394.04(+/-810.81)
25%	2-1	4499.58
25%	2-2	4233.69
25%	2-3	4213.46
25%	2-4	3792.26
25%	2-5	2053.44
Mean dpm/Animal		3758.49(+/-986.20)
50%	3-1	7972.5
50%	3-2	14354.64
50%	3-3	34794.89
50%	3-4	4304.62
50%	3-5	6735.07
Mean dpm/Animal		8341.71(+/-4288.40, excludes outlier animal 3-3)
100%	4-1	8951.52
100%	4-2	6870.22
100%	4-3	7371.75
100%	4-4	10779.57
100%	4-5	5208.36
Mean dpm/Animal		7836.28
Positive Control	5-1	25621.3
Positive Control	5-2	27410.54
Positive Control	5-3	25399.66
Positive Control	5-4	24164.43
Positive Control	5-5	8301.48
Mean dpm/Animal		22179.48(+/-7844.08)

 

Applicant's summary and conclusion

Interpretation of results:

Category 1 (skin sensitising) based on GHS criteria

Conclusions:

The test substance is a skin sensitizer.

Executive summary:

The potential for dermal sensitization for the test substance was determined in an OECD Guideline 429 Local Lymph Node Assay test.  Test concentrations of 25%, 50%, and 100% of the test substance in ethanol/diethylphthalate 1:3 were used.  Hexyl cinnamic aldehyde was used as a positive control.  5 animals per dose were tested. Test solutions were applied for three consecutive days. A threefold or greater increase in 3HTdR incorporation was considered a positive response.  The stimulation index results were as follows: 2.7 (25%), 5.98 (50%), 5.62 (100%), and 15.91 (positive control).  The EC3 was calculated to be 27.29.  Based on the results, the test substance is considered a skin sensitizer.