Isooctyl palmitate

Skin sensitisation

Administrative data

Endpoint:

skin sensitisation: in vitro

Type of information:

experimental study

Adequacy of study:

key study

Study period:

2019

Reliability:

1 (reliable without restriction)

Rationale for reliability incl. deficiencies:

guideline study

Data source

Reference

Reference Type:

study report

Title:

Unnamed

Year:

2019

Report date:

2019

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:

Isooctyl palmitate

EC Number:

215-675-9

EC Name:

Isooctyl palmitate

Cas Number:

1341-38-4

Molecular formula:

C24H48O2

IUPAC Name:

6-methylheptyl hexadecanoate

Test material form:

liquid

Remarks:

a colourless liquid

In vitro test system

Details on the study design:

Main study
Day 1:
Each animal was identified and the body weight was recorded. To the dorsum of each ear 25 µL of the appropriate dilution of the test item, or the vehicle alone was applied.
Days 2 and 3:
The application procedure carried out on day 1 was repeated.
Days 4 and 5:
No treatment.
Day 6:
The body weight of each animal was recorded. 250 µL of sterile phosphate-buffered saline (PBS) containing 2 µCi (7.4 x 104 Bq) of 125I-iododeoxyuridine and 10-5M fluorodeoxyuridine was injected into all test and control mice via the tail vein.
Five hours later, the animals were sacrificed. The draining auricular lymph nodes from each ear were excised and pooled in PBS for each experimental group (pooled treatment group approach).
Preparation of cell suspensions
Cell suspension of lymph node cells from pooled treatment groups was prepared by gentle mechanical disaggregation by a glass homogenizer. Lymph node cells were centrifuged by 600 x g at 4 C for 10 min. Cell suspensions were precipitated with 5 % trichloroacetic acid (TCA) at 4 C for 18 h. Pellets were centrifuged at 2000 x g at 4 C for 5 min., re-suspended in 1 ml TCA and transferred to gamma counting tubes for 125I-counting.

Results and discussion

Positive control results:

weight (g) lymph nodes DPM SI
Positive Control 0.0734 10 8076.83 5.57

In vitro / in chemico

Results

Parameter:

other: Stimulation Indices (SI)

Value:

3

Vehicle controls validity:

valid

Positive controls validity:

valid

Other effects / acceptance of results:

The skin sensitization potential of Isooctyl palmitate was evaluated by LLNA method, which basic underlying principle is that sensitizers induce a primary proliferation of lymphocytes in the auricular lymph nodes draining the site of chemical application.
In the present study, the test item was applied to the dorsum of each ear of five female mice (CBA/Ca) per group over three consecutive days, at three concentrations. All animals survived throughout the test period without showing any clinical signs of toxicity. Calculated SI values in treated groups remained under the value of 3, which is the threshold to consider the substance as a sensitizer. Therefore, it was not possible to calculate an EC3 value.
These results demonstrate that the test item Isooctyl palmitate was not a skin sensitizer under the test conditions of this study.

Any other information on results incl. tables

The Lymph node weight, DPM, SI, EC3 values.

		Lymph node	Number of
		weight (g)	lymph nodes	DPM	SI	EC3 (%)
Control		0.0309	10	1449.03	-	-
Positive Control		0.0734	10	8076.83	5.57
Isooctyl palmitate 25 %		0.0419	10	1779.00	1.23
Isooctyl palmitate 50 %		0.0464	10	2036.66	1.41
Isooctyl palmitate 100%		0.0529	10	2461.95	1.70

Applicant's summary and conclusion

Interpretation of results:

GHS criteria not met

Conclusions:

The skin sensitizing potential of Isooctyl palmitate was assessed using the murine local lymph node assay.
Based on the results of this study, Isooctyl palmitate is not considered a skin sensitizer under the conditions of this LLNA study.