Vinyl laurate

Skin sensitisation

Administrative data

Endpoint:

skin sensitisation: in vivo (LLNA)

Type of information:

experimental study

Adequacy of study:

key study

Study period:

2006-11-01 until 2007-01-18

Reliability:

1 (reliable without restriction)

Rationale for reliability incl. deficiencies:

other: Good laboratory practice guideline study (OECD).

Data source

Reference

Reference Type:

study report

Title:

Unnamed

Year:

2007

Report date:

2007

Materials and methods

Test guideline

Qualifier:

according to guideline

Guideline:

OECD Guideline 429 (Skin Sensitisation: Local Lymph Node Assay)

Deviations:

no

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:

Vinyllaurate

IUPAC Name:

Vinyllaurate

Details on test material:

- Name of test material (as cited in study report): Vinyllaurate
- Physical state: colourless liquid
- Composition of test material, percentage of components: as stated in substance data
- Stability under test conditions: stable
- Storage condition of test material: in original container, at room temperature, in the dark

In vivo test system

Test animals

Species:

mouse

Strain:

CBA

Sex:

female

Details on test animals and environmental conditions:

TEST ANIMALS
- Source: Charles River France; L'Arbrescle Cedex, France
- Weight at study initiation: 23-28 g
- Diet (e.g. ad libitum): ad libitum
- Water (e.g. ad libitum): ad libitum
- Acclimation period: at least 5 days


ENVIRONMENTAL CONDITIONS
- Temperature (°C):20.6 - 23.3 °C
- Humidity (%): 39-67%
- Air changes (per hr): 15
- Photoperiod (hrs dark / hrs light): 12 h dark, 12 h light

Study design: in vivo (LLNA)

Vehicle:

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

Concentration:

0, 10, 25 and 50%

No. of animals per dose:

5

Details on study design:

RANGE FINDING TESTS:
- Compound solubility: The test item was soluble in the vehicle. Homogenicity was obtained.
- Irritation: Erythema up to grade 2 (50% solution ) and 3 (pure substance) were observed after treatment on three consecutive days..


MAIN STUDY
ANIMAL ASSIGNMENT AND TREATMENT
- Criteria used to consider a positive response: If the results indicate a stimulation index (SI) >= 3, the test substance may be regarded as a skin sensitizer based on guideline and recommendations of ICCVAM


TREATMENT PREPARATION AND ADMINISTRATION:
Induction: Days 1,2,3:
The dorsal surface of both ears was epidermally treated (25 µl/ear) with the test substance concentration, at approximately the same time per day. The concentrations were mixed throughly using a vortex mixer immedieately prior to dosing. The control animals were treated the same as the experimental animals except that, instead of the test item, the vehicle alone was administered.
Treatment: Day 6
All animls were injected via the tail vein with 0.25 ml of sterile phosphate buffered saline containing 20 µCi of 3H-methyl thymidine. After approximately five hours all animals were killed by intraperitoneal injection with pentobarbital (0.2 ml/animal) The draining (auricular) lymph node of each ear was excised.
The relative size of the nodes (as compared to normal) was estimatedby visual examination and abnormalities of the nodes and surrounding area were recorded. The nodes were pooled for each animal in approximately 3 ml phosphate buffered saline.
Tissue processing for radioactivity: Day 6
A single cell suspension of local lymph node cells (LNC) was prepared in phosphate buffered saline by gentle separation through stainless steel gauze. LNC was washed twice with an excess of phosphate buffered saline by centrifugation at 200 g for 10 minutes at 4°C. To precipitate the DNA, the LNC were exposed to 5% trichloroacetic acid at 4 °C during the night.
Radioactivity measurements: Day 7
Precipitates were recovered by centrifugation, resuspended in 1 ml TCA and transferred to 10 ml of Ultima Gold cocktail as the scintillation fluid. Radioactive measurements were performed using a Packard scintilation counter. Counting time was statistical precision of +/- 0.2% or a maximum of 5 minutes whichever comes first. The counter was programmed to automatically substract background and convert Counts Per Minute (CPM) to Disintegrations Per Minute (DPM).

Positive control substance(s):

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

Statistics:

not mentioned in report

Results and discussion

Positive control results:

The reliability control worked as expected. The test was prepared separately in September 2006 with 5, 10 and 25% .alpha.-Hexylcinnamicaldehyde. The SI values calculated for the substance concentrations 5, 10 and 25% were 1.4, 2.2 and 6.2 respectively. The EC3 value of 13.1% was calculated using linear interpolation.

In vivo (LLNA)

Results

Results 1

Parameter:

SI

Remarks on result:

other: 10% test substance solution 0.8 +/- 0.5 25% test substance solution 1.3 +/- 0.4 50% test substance solution 1.6 +/- 0.4 control: 1.0

Results 2

Parameter:

other: disintegrations per minute (DPM)

Remarks on result:

other: 10% test substance solution 231 +/- 89 25% test substance solution 400 +/- 128 50% test substance solution 501 +/- 140 control: 304 +/- 80

Applicant's summary and conclusion

Interpretation of results:

not sensitising

Remarks:

Migrated information

Conclusions:

The substance is not sensitizing to the skin in a OECD 29 Mouse Local Lymph Node Assay under the conditions used.

Executive summary:

A Local Lymph Node Assay according to OECD 429 has been performed with Vinyl laurate. Test substance concentrations selected for the main study were based on the results of a preliminary study. In the main study, three groups of five experimental animals were treated with test substance concentrations of 10, 25 and 50 % on three consecutive days by open application on the ears. Five vehicle control animals were similarly treated but with vehicle alone (acetone/olive oil). Three days after the last exposure all animals were injected with 3H-methyl thymidine and after five hours the draining (auricular) lymph nodes were excised.

After precipitating the DNA of the lymph node cells, radioactivity measurements were performed. The activity was expressed as the number of Desintegrations Per Minute (DPM) and a stimulation index was subsequently calculated for each group.

Skin irritation was observed in the animals examined. The higher dose groups showed more severe skin irritation. The irritation of the ears as shown by the animals was considered not to have a toxicologically significant effect on the activity of the nodes.

All nodes of the experimantal and control groups were considered normal in size. No macroscopic abnormalities of the surrounding area were noted. Mean DPM/animal values for the experimental groups treated with test substance concentrations 10, 25 and 50 % were 231, 400 and 501 respectively. The mean DPM/animal value for the vehicle control was 304. The Stimulation indicees (SI) for the substance concentrations 10, 25 and 50% were 0.8, 1.3 and 1.6 respectively.

Since there was no indication that the test substance could elicit an SI >= 3 when tested up to 50% it was established that the EC3value (if any) exceeds 50%.

The six months reliability check with hexylcinnamic aldehyde indicates that the Local Lymph Node Assay as performed by the testing facility is an appropriate model for testing for contact hypersensitivity.

Based on the results according to the EU criteria for classification and labeling requirements Vinyl laurate does not have to be classified and has no obligatory labeling requirement for sensitization by skin contact.