Pentatriacontan-18-one

Skin sensitisation

Administrative data

Endpoint:

skin sensitisation: in vivo (LLNA)

Type of information:

experimental study

Adequacy of study:

key study

Reliability:

1 (reliable without restriction)

Rationale for reliability incl. deficiencies:

guideline study

Justification for type of information:

For in vitro tests, the test item is insoluble in all solvent indicated by the respective OECD guidelines at the required concentrations. Under these circumstances, in vitro skin sensitization testing of Stearone in accordance with OECD 442C, OECD 442D and OECD 422E was not possible. Other validated in vitro tests on skin sensitization are not available at present.

Data source

Reference

Reference Type:

study report

Title:

Unnamed

Year:

2018

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:

Pentatriacontan-18-one

EC Number:

207-993-1

EC Name:

Pentatriacontan-18-one

Cas Number:

504-53-0

Molecular formula:

C35H70O

IUPAC Name:

pentatriacontan-18-one

Test material form:

solid

In vivo test system

Test animals

Species:

mouse

Strain:

CBA/Ca

Details on test animals and environmental conditions:

Age at First Dose 10-11 weeks, female animals were non-pregnant and nulliparous were used
Animal Health The health condition of animals was examined by a veterinarian
before initiation of the study. Animals were healthy, without visible signs of disease.
Acclimation The animals were acclimated in identical conditions as during the experiment for 6 days prior to the start of treatment. The acclimati on was according to standard operation procedures.
Housing Condition The animals were housed in IVC polycarbonate cages (5 animals per cage) suspended on stainless steel racks, in a room equippe d with central air-conditioning. The room temperature was within the range of 22 ± 3 °C, relative humidity was within the range of 5 0 - 60 %. The light regimen was set to a 12-hour light / 12-hour dark cycle. The sanitation was performed according to standard op eration procedures.
Diet A laboratory food ssniff (ssniff Spezialdiäten GmbH, Germany) was served ad libitum, each day approximately at the same time. Th e certificate of analysis is included in the raw data.
Water The animals received tap water for human consumption. Supply of drinking water was unlimited. The quality of drinking water is pe riodically monitored (including microbiological control) and recorded; certificate of analysis is included in raw data.
Bedding Lignocel S3/4, Lufa - ITL GmbH, Germany
Animals Identification Each animal was marked with permanent pen on the tail. Each cage was affixed with a cage card containing pertinent animal and s tudy information.
Justification for
the Choice of Species The CBA/Ca mice are the standard experimental rodent of choice and recommended by OECD Guideline No. 429.

Study design: in vivo (LLNA)

Vehicle:

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

Concentration:

The doses were selected from the concentration series 100 %, 50 %, 25 %, 10 %, 5 %, 2.5 % etc. according to OECD Guideline No. 429.
The starting concentration was determined according to pre-screen test result.
Based on the observations recorded in the preliminary test, the concentrations of 100, 50 and 25 % were selected for the main test.

No. of animals per dose:

5 females – negative control (vehicle)
5 females – positive control
15 females – test item
4 females - pre-screen test, plus spare animals

Details on study design:

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 euthanizedsacrificed. The draining auricular lymph nodes from each ear were excised and pooled in PBS for each experimental group (pooled treatment group approach).

Positive control substance(s):

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

Results and discussion

Positive control results:

Lymph node Number of
weight (g) lymph nodes DPM SI EC3 (%)
Control 0.0324 10 1333 - -


Positive Control 0.0642 10 9776 6.63

In vivo (LLNA)

Results

Results 1

Key result

Parameter:

SI

Value:

1.06

Test group / Remarks:

Stearone 100%

Results 2

Key result

Parameter:

SI

Value:

0.96

Test group / Remarks:

Stearone 50%

Results 3

Key result

Parameter:

SI

Value:

0.87

Test group / Remarks:

Stearone 25%

Cellular proliferation data / Observations:

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.

Any other information on results incl. tables

In comparison with the control group, a minor increase of the pooled lymph node weights was observed at concentration of 100 %. The pooled lymph node weights of treated groups were 0.0293 g for 25 % concentration, 0.0302 g for 50 % concentration and 0.0336 g for 100 % concentration of test item. The lymph node weight of control group and positive control group were 0.0324 g and 0.0642g, respectively. The DPM values for the three treated groups were 1157 (25 %), 1275 (50 %) and 1413 (100 %), respectively. The SI values for the three treated groups were 0.87 (25 %), 0.96 (50 %) and 1.06 (100 %), respectively. The EC3 value could not be calculated, since none of the tested concentrations induced a S.I. was not greater than the threshold value of 3.

The Lymph node weights, DPM and SI values are shown in Table 6.

Table 6.The Lymph node weight, DPM, SI, EC3 values.

		Lymph node	Number of
		weight (g)	lymph nodes	DPM	SI	EC3 (%)
Control		0.0324	10	1333	-	-
Positive Control		0.0642	10	9776	6.63*
Stearone	25%	0.0293	10	1157	0.87
Stearone	50%	0.0302	10	1275	0.96
Stearone	100%	0.0336	10	1413	1.06

*Calculated with corresponding control value of 1475 DPM (Appendix 2)

Applicant's summary and conclusion

Interpretation of results:

GHS criteria not met

Conclusions:

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

Executive summary:

The sensitization potential of Stearonewas evaluated using the Local Lymph Node Assay (LLNA). The LLNA has been developed to determine the allergic contact sensitization potential of chemicals.

Based on the recommendations of the OECD Guideline 429, the test item was suspended in Acetone/Olive Oil, 4:1 (v/v). The positive control (a-Hexylcinnamic aldehyde) (25 %) was dissolved in the same vehicle.

ThePre-screen test was performed using the dose of 100 %. Based on the observations recorded in the Pre-screen tests, the concentration of 100 % was selected as top dose for the main test.

Five female mice (CBA/Ca) per group were topically exposed (dorsum of both ears) to the test item at concentrations of 25 %, 50 % and 100 %, to the positive control and to the vehicle only. Lymphocyte proliferation was measured using incorporation of radioactive¹²⁵I-iododeoxyuridine and 10^-5M fluorodeoxyuridinein the draining lymph nodes. The radioactive incorporation was expressed as disintegrations per minute (DPM)/pooled treatment group and compared with DPM value from the vehicle control group and expressed as the Stimulation Index (SI).

After application of the test itemat three concentrations (25 %, 50 % and 100 % w/v) the animals did not show visible clinical symptomsof either local irritation or systemic toxicity.

In this study the Stimulation Indices (SI) of0.87, 0.96 and 1.06 were determined with the test item at concentrations of 25 %, 50 %, and 100 % inAcetone/Olive Oil 4:1, respectively. The EC3 value could not be calculated, since none of the tested concentrations induced a SI greater than the threshold value of 3.  

The test item Stearoneis not considered a skin sensitizer under the test conditions of this study.