Isooctadecanoic acid, 1,1'-(2,2-dimethyl-1,3-propanediyl) ester

Skin sensitisation

Administrative data

Endpoint:

skin sensitisation: in vivo (LLNA)

Type of information:

experimental study

Adequacy of study:

key study

Study period:

18 Jun - 14 Jul 2014

Reliability:

1 (reliable without restriction)

Rationale for reliability incl. deficiencies:

other: GLP compliant 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)

Version / remarks:

(2010)

Deviations:

yes

Remarks:

(deviations from the maximum level of daily mean relative humidity occurred)

GLP compliance:

yes

Type of study:

mouse local lymph node assay (LLNA)

Test material

Test material information

Constituent 1

Reference substance name:

109884-54-0

Cas Number:

109884-54-0

IUPAC Name:

109884-54-0

Test material form:

other: liquid

Details on test material:

- Name of test material (as cited in study report): only trade name given
- Physical state: clear colourless liquid
- Analytical purity: 100%
- Batch No.: OE31003999
- Expiration date of the batch: 03 October 2017
- Stability under test conditions: in vehicle acetone: stable; in vehicle olive oil: stable
- Storage condition of test material: at room temperature in the dark
- pH (1% in water, indicative range): 6.5 - 5.7

In vivo test system

Test animals

Species:

mouse

Strain:

other: CBA/J strain, inbred, SPF-Quality

Sex:

female

Details on test animals and environmental conditions:

TEST ANIMALS
- Source: Janvier, Le Genest-Saint-Isle, France
- Age at study initiation: approx. 10 weeks
- Mean weight at study initiation: 23 g (body weight variation was within +/- 20%)
- Housing: group housed. On Day 6, the animals were group housed in cages with a sheet of paper instead of sawdust and cage enrichment.
- Diet: pelleted rodent diet, ad libitum
- Water: tap water, ad libitum
- Acclimation period: at least 5 days

ENVIRONMENTAL CONDITIONS
- Temperature (°C): 18 - 24
- Humidity (%): 40 - 70
- Air changes (per hr): at least 10
- Photoperiod (hrs dark / hrs light): 12/12

Study design: in vivo (LLNA)

Vehicle:

acetone/olive oil (4:1 v/v)

Concentration:

0, 25, 50 and 100% (w/w)

No. of animals per dose:

5

Details on study design:

RANGE FINDING TESTS:
Two test substance concentrations were tested; a 50% and 100% concentration. The test system, procedures and techniques were identical to those used in the main study except that the assessment of lymph node proliferation and necropsy were not performed. Two young adult animals per concentration were selected. Each animal was treated with one concentration on three consecutive days. Ear thickness measurements were conducted prior to dosing on Days 1 and 3, and on Day 6.
Very slight erythema was noted for both animals treated at 100% between Days 2 and 5. No irritation was observed in the animals treated at 50%. Variations in ear thickness during the observation period were less than 25% from Day 1 pre-dose values for all animals. No signs of systemic toxicity were observed in any of the animals examined.
Based on these results, the highest test substance concentration selected for the main study was a 100% concentration.

MAIN STUDY
ANIMAL ASSIGNMENT AND TREATMENT
- Name of test method: ³H-methyl thymidine incorporation determined by using a Packard scintillation counter.
- Criteria used to consider a positive response: A Stimulation Index (SI) is calculated for each group using the individual SI values (ratio of the DPM/animal compared to DPM/vehicle control group). If the results indicate a SI ≥ 3, the test substance may be regarded as a skin sensitizer.

TREATMENT PREPARATION AND ADMINISTRATION:
The dorsal surface of both ears was topically treated (25 μL/ear) with the test substance concentration on Day 1, 2 and 3, at approximately the same time on each day. The control animals were treated in the same way as the experimental animals, except that the vehicle was administered instead of the test substance. On Day 6, each animal was injected via the tail vein with 0.25 mL of sterile phosphate buffered saline (PBS) containing 20 μCi of ³H-methyl thymidine. After approximately five hours, the draining (auricular) lymph node of each ear was excised. The relative size of the nodes (as compared to normal) was estimated by visual examination and abnormalities of the nodes and surrounding area were recorded. The nodes were pooled for each animal in approximately 3 mL PBS and radioactive measurements were performed using a Packard scintillation counter.

Positive control substance(s):

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

Results and discussion

Positive control results:

The six-month reliability check with alpha-hexylcinnamaldehyde indicates that the Local Lymph Node Assay as performed at WIL Research Europe is an appropriate model for testing for contact hypersensitivity. The SI values calculated for the substance concentrations 5, 10 and 25% were 1.2, 1.4 and 4.7, respectively.

In vivo (LLNA)

Results

Results 1

Parameter:

SI

Remarks on result:

other: The SI values calculated for the substance concentrations 25, 50 and 100% were 1.1, 1.0 and 1.6, respectively.

Results 2

Parameter:

other: disintegrations per minute (DPM)

Remarks on result:

other: Mean DPM/animal values for the experimental groups treated with test substance concentrations 25, 50 and 100% were 365, 310 and 518 DPM, respectively. The mean DPM/animal value for the vehicle control group was 326 DPM.

Any other information on results incl. tables

No irritation of the ears was observed in any of the animals examined. No mortality occurred and no clinical signs of systemic toxicity were observed in the animals of the main study. Body weights and body weight gain of experimental animals remained in the same range as controls over the study period. All auricular lymph nodes of the animals of the experimental and control groups were considered normal in size. No macroscopic abnormalities of the surrounding area were noted for any of the animals.

Table 1: Body weights, radioactivity counts (DPM) and Stimulation Index (SI)

group	test substance (% w/w)	animal	body weight (g)		DPM/animal	mean DPM ± SEM	mean SI ± SEM
			Day 1	Day 6
1	0	1	23	25	367	326  ± 45	1.0  ± 0.2
		2	23	25	316
		3	21	21	293
		4	24	23	189
		5	25	23	464
2	25	6	25	25	576	365  ± 72	1.1  ± 0.3
		7	22	22	429
		8	21	22	365
		9	23	23	317
		10	21	21	136
3	50	11	24	24	218	310  ± 60	1.0  ± 0.2
		12	22	24	332
		13	24	24	496
		14	21	22	357
		15	24	24	149
4	100	16	22	23	293	518  ± 97	1.6  ± 0.4
		17	22	23	662
		18	23	24	465
		19	21	22	813
		20	20	21	356

Applicant's summary and conclusion

Interpretation of results:

not sensitising

Remarks:

Migrated information Criteria used for interpretation of results: EU

Conclusions:

CLP: not classified