Decyl laurate

Endpoint summary

Description of key information

GARD assay: not skin sensitising

(Read across, GPMT, LLNA, human RIPT): not skin sensitising

Key value for chemical safety assessment

Skin sensitisation

Link to relevant study records

Reference

Reference 1

Endpoint:

skin sensitisation: in vivo (non-LLNA)

Type of information:

experimental study

Adequacy of study:

weight of evidence

Study period:

06 - 20 Feb 2002

Reliability:

2 (reliable with restrictions)

Rationale for reliability incl. deficiencies:

other: GLP-guideline study with acceptable restrictions (analytical purity was not specified, lack of methodological details).

Qualifier:

according to guideline

Guideline:

OECD Guideline 406 (Skin Sensitisation)

Deviations:

yes

Remarks:

analytical purity of test substance not specified, lack of methodological details

Qualifier:

according to guideline

Guideline:

EU Method B.6 (Skin Sensitisation)

Deviations:

yes

Remarks:

analytical purity of test substance not specified, lack of methodological details

GLP compliance:

yes (incl. QA statement)

Remarks:

The Department of Health of the Government of the United Kingdom

Type of study:

guinea pig maximisation test

Justification for non-LLNA method:

The Guinea Pig Maximisation Test was performed prior to the requirement of performing a Local Lymph Node Assay as the 1st-choice in vivo study.

Species:

guinea pig

Strain:

Dunkin-Hartley

Sex:

male

Details on test animals and environmental conditions:

TEST ANIMALS
- Source: David Hall Limited, UK
- Age at study initiation: 8 - 12 weeks
- Weight at study initiation: 349 g
- Housing: singly or in pairs in solid floor propylene cages
- Diet: ad libitum, certified guinea pig diet (Code 5026, PMI Nutrition International, UK)
- Water: ad libitum
- Acclimation period: at least 5 days


ENVIRONMENTAL CONDITIONS
- Temperature (°C): 17-23
- Humidity (%): 30-70
- Air changes (per hr): 15
- Photoperiod (hrs dark / hrs light): 12/12

Route:

intradermal and epicutaneous

Vehicle:

arachis oil

Concentration / amount:

Intradermal Induction: 1% v/v in arachis oil BP
Topical Induction: undiluted as supplied
Topical Challenge: 75%o and 50% v/v in arachis oil BP

No.:

#1

Route:

epicutaneous, occlusive

Vehicle:

arachis oil

Concentration / amount:

Intradermal Induction: 1% v/v in arachis oil BP
Topical Induction: undiluted as supplied
Topical Challenge: 75%o and 50% v/v in arachis oil BP

No. of animals per dose:

10

Details on study design:

RANGE FINDING TESTS: Yes, treatment concentrations of the main study are based on these results.

MAIN STUDY
A. INDUCTION EXPOSURE
- No. of exposures: 2
- Exposure period: Intradermal induction and epidermal induction
- Test groups: 10 animals, TS
- Control group: animals treated with vehicle
- Concentrations: 1% dilution of the test substance in arachis oil was used for intradermal induction and 100% used for epidermal induction


B. CHALLENGE EXPOSURE
- No. of exposures: 1
- Test groups: 10 animals, TS
- Control group: 5, treated analogous to the test groups
- Concentrations: 50% and 75% solution in arachis oil
- Evaluation (hr after challenge): 24 and 48 h

Positive control substance(s):

yes

Remarks:

alpha-hexylcinnamaldehyde, 2-Mercaptobenzothiazole

Positive control results:

Reliability checks had been performed 2 times a year with 10 test and 5 control animals using alpha-hexylcinnamaldehyde and 2-Mercaptobenzothiazole as positive control substances confirming the sensititvity of the used animal strain.

Key result

Reading:

1st reading

Hours after challenge:

24

Group:

test chemical

Dose level:

50%

No. with + reactions:

0

Total no. in group:

10

Clinical observations:

none

Remarks on result:

other: Reading: 1st reading. . Hours after challenge: 24.0. Group: test group. Dose level: 50% . No with. + reactions: 0.0. Total no. in groups: 10.0. Clinical observations: none.

Key result

Reading:

1st reading

Hours after challenge:

24

Group:

test chemical

Dose level:

75%

No. with + reactions:

1

Total no. in group:

10

Clinical observations:

none

Remarks on result:

other: Reading: 1st reading. . Hours after challenge: 24.0. Group: test group. Dose level: 75%. No with. + reactions: 1.0. Total no. in groups: 10.0. Clinical observations: none.

Key result

Reading:

1st reading

Hours after challenge:

24

Group:

negative control

Dose level:

50%

No. with + reactions:

0

Total no. in group:

5

Clinical observations:

none

Remarks on result:

other: Reading: 1st reading. . Hours after challenge: 24.0. Group: negative control. Dose level: 50%. No with. + reactions: 0.0. Total no. in groups: 5.0. Clinical observations: none.

Key result

Reading:

1st reading

Hours after challenge:

24

Group:

negative control

Dose level:

75%

No. with + reactions:

0

Total no. in group:

5

Clinical observations:

none

Remarks on result:

other: Reading: 1st reading. . Hours after challenge: 24.0. Group: negative control. Dose level: 75%. No with. + reactions: 0.0. Total no. in groups: 5.0. Clinical observations: none.

Reading:

2nd reading

Hours after challenge:

48

Group:

test chemical

Dose level:

50%

No. with + reactions:

0

Total no. in group:

10

Clinical observations:

none

Remarks on result:

other: Reading: 2nd reading. . Hours after challenge: 48.0. Group: test group. Dose level: 50% . No with. + reactions: 0.0. Total no. in groups: 10.0. Clinical observations: none.

Reading:

2nd reading

Hours after challenge:

48

Group:

test chemical

Dose level:

75%

No. with + reactions:

0

Total no. in group:

10

Clinical observations:

none

Remarks on result:

other: Reading: 2nd reading. . Hours after challenge: 48.0. Group: test group. Dose level: 75%. No with. + reactions: 0.0. Total no. in groups: 10.0. Clinical observations: none.

Reading:

2nd reading

Hours after challenge:

48

Group:

negative control

Dose level:

50%

No. with + reactions:

0

Total no. in group:

5

Clinical observations:

none

Remarks on result:

other: Reading: 2nd reading. . Hours after challenge: 48.0. Group: negative control. Dose level: 50%. No with. + reactions: 0.0. Total no. in groups: 5.0. Clinical observations: none.

Reading:

2nd reading

Hours after challenge:

48

Group:

negative control

Dose level:

75%

No. with + reactions:

0

Total no. in group:

5

Clinical observations:

none

Remarks on result:

other: Reading: 2nd reading. . Hours after challenge: 48.0. Group: negative control. Dose level: 75%. No with. + reactions: 0.0. Total no. in groups: 5.0. Clinical observations: none.

Key result

Reading:

1st reading

Hours after challenge:

24

Group:

positive control

Dose level:

75%

No. with + reactions:

4

Total no. in group:

10

Remarks on result:

positive indication of skin sensitisation

Challenge readings

Group	Animal Number	Skin Reactions (Hours after Removal of Dressings)
		24 h				48 h
		50%		75%		50%		75%
		Er	Ed	Er	Ed	Er	Ed	Er	Ed
Test Group	1	0	0	0	0	0	0	0	0
	2	0	0	0	0	0	0	0	0
	3	0	0	0	0	0	0	0	0
	4	0	0	0	0	0	0	0	0
	5	0	0	0	0	0	0	0	0
	6	0	0	0	0	0	0	0	0
	7	0	0	0	0	0	0	0	0
	8	0	0	0	0	0	0	0	0
	9	0	0	0	0	0	0	0	0
	10	0	0	1	0	0	0	0	0
Control Group	11	0	0	0	0	0	0	0	0
	12	0	0	0	0	0	0	0	0
	13	0	0	0	0	0	0	0	0
	14	0	0	0	0	0	0	0	0
	15	0	0	0	0	0	0	0	0

Ed: Edema

Er: Erythema

Positive controlls were in the range of the historical controls.

No deaths occured. No significant differences in the gain of body weight was observed between treatment and control group.

A transient challenge reaction (discrete erythema) was observed in one animal of the test group at 24 h observation with desquamation at the 48 h observation. The erythema was not apparent at the 48 h observation and therefore not attributed to contact sensitization

Interpretation of results:

other: CLP/EU GHS criteria not met, no classification required according to Regulation (EC) No 1272/2008.

Reference 2

Endpoint:

skin sensitisation: in vivo (LLNA)

Type of information:

experimental study

Adequacy of study:

weight of evidence

Study period:

26 May - 23 Jun 2010

Reliability:

1 (reliable without restriction)

Rationale for reliability incl. deficiencies:

guideline study

Qualifier:

according to guideline

Guideline:

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

Version / remarks:

2002

Deviations:

no

Qualifier:

according to guideline

Guideline:

EU Method B.42 (Skin Sensitisation: Local Lymph Node Assay)

Deviations:

no

Qualifier:

according to guideline

Guideline:

EPA OPPTS 870.2600 (Skin Sensitisation)

Version / remarks:

2003

Deviations:

no

GLP compliance:

yes

Type of study:

mouse local lymph node assay (LLNA)

Species:

mouse

Strain:

other: CBA/J

Sex:

female

Details on test animals and environmental conditions:

TEST ANIMALS
- Source: Janvier, Le Genest-Saint-Isle, France
- Age at study initiation: approximately 10 weeks
- Weight at study initiation: 22-25 g (range)
- Housing: animals were housed individually in labelled Makrolon cages (MI type, height 12.5 cm) containing sterilised sawdust as bedding material (Litalabo, S.P.P.S., Argenteuil, France) and paper as cage-enrichment (Enviro-dri, Wm. Lillico & Son (Wonham Mill Ltd.), Surrey, UK). The paper was removed on Day 1 prior to dosing and was supplied again after scoring of the ears on the third day 3. During the acclimation period the animals were housed in groups in Macrolon cages (MIII type, height 18 cm).
- Diet: pelleted rodent diet (SM R/M-Z from SSNIFF Spezialdiäten GmbH, Soest, Germany), ad libitum
- Water: tap water, ad libitum
- Acclimation period: at least 5 days

ENVIRONMENTAL CONDITIONS
- Temperature (°C): 20.5-23.1
- Humidity (%): 41-68
- Air changes (per hr): approximately 15
- Photoperiod (hrs dark / hrs light): 12/12

IN-LIFE DATES: From: 26 May 2010 To: 23 Jun 2010

Vehicle:

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

Concentration:

25, 50 and 100% (w/w)

No. of animals per dose:

5

Details on study design:

RANGE FINDING TESTS:
- Irritation: A preliminary irritation study was performed according to the procedure of the main study. Two mice were treated daily for 3 consecutive days with either a 50% solution or 100% test substance. 3-4 hours after the last exposure, the irritation severity on the treated skin site was assessed. The body weight was recorded on Day 1 and 3. Very slight erythema (grade 1 of 4) was observed on both the treated sites in the animal exposed to 100% concentration. None of the animals exhibited signs of toxicity during the study period and the body weight was not affected by the treatment. Based on these results, the highest test substance concentration selected for the main study was 100%.

MAIN STUDY
ANIMAL ASSIGNMENT AND TREATMENT
- Name of test method: 3H-methyl thymidine incorporation determined by beta-scintillation counting
- Criteria used to consider a positive response: DMP values will be measured for each animal and for each dose group. The stimulation Index (SI) will be calculated for each group. The SI is the ratio of the DPM/group compared to DPM/vehicle control group. If the results indicate a SI ≥3, the test substance may be regarded as a skin sensitiser, based on the test guidelines and the recommendations done by ICCVAM.

TREATMENT PREPARATION AND ADMINISTRATION:
The test substance formulations (w/w) were prepared within 4 hours prior to each treatment. No adjustment was made for specific gravity of the vehicle. Homogeneity was obtained to visually acceptable levels.
During the induction phase (Day 1-3), the dorsal surface of both ears was epidermally treated (25µL/ear) with the vehicle control or 25, 50 and 100% test substance, at approximately the same time each day for 3 consecutive days. On Day 6, all the animals were injected via the tail vein with 0.25 mL sterile phosphate buffered saline (PBS), containing 20 µCi 3H-methyl thymidine. After approximately 5 hours, all the animals were sacrificed by intraperitoneal injection of Euthasol 20% and the draining (auricular) lymph node of both ears 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. A single cell suspension of lymph node cells (LNC) was prepared the same day in PBS by gentle separation through a stainless steel gauze (diameter 125 µm).
A single cell suspension of LNCs was prepared in PBS by gentle separation through stainless steel gauze (diameter 125 µm). To precipitate the DNA, the LNCs were exposed to 5% trichloroacetic acid (TCA) and stored in the refrigerator until the next day.
Radioactivity measurements were performed on Day 7, using Ultima Gold cocktail as the scintillation fluid. The scintillation counter was programmed to automatically subtract background and convert Counts Per Minute (CPM) to Disintegrations Per Minute (DPM).

Positive control substance(s):

other: A reliability check was performed with alpha-hexylcinnamaldehyde every 6 months to demonstrate that the LLNA test system is reliable and sufficiently sensitive

Positive control results:

A reliability check with a positive control substance was performed every 6 months to demonstrate that the LLNA test system, as used by the test laboratory, is reliable and sufficiently sensitive. In the test performed in April 2010 (project No. 494039), 5, 10 and 25% alpha-hexylcinnamaldehyde, technical grade in acetone/olive oil (4:1 v/v) was used as the positive control. The SI values calculated for the substance concentrations 5, 10 and 25% were 1.7, 2.7 and 8.8 respectively. The SI-value for the vehicle control was 1.0. An EC3 value of 10.7% was calculated using linear interpolation. The calculated EC3 value was found to be in the acceptable range of 2 and 20%. The results of the 6 -monthly HCA reliability checks in CBA/J female mice of the recent years were 14.1, 13.8, 13.9, 16.0, 11.9 and 16.9%. Based on the results, it was concluded that the Local Lymph Node Assay in the mouse as supplied by Janvier performed at NOTOX is an appropriate model for testing for contact hypersensitivity.

Key result

Parameter:

SI

Value:

1

Test group / Remarks:

control

Key result

Parameter:

SI

Value:

1.2

Test group / Remarks:

25%

Key result

Parameter:

SI

Value:

2

Test group / Remarks:

50%

Key result

Parameter:

SI

Value:

2.1

Test group / Remarks:

100%

Cellular proliferation data / Observations:

The mean DPM values for the control, 25, 50 and 100% groups were 488, 571, 951 and 1013, respectively (see Table 1). The slight increase in DPM with increasing dose level was not statistically significant.

Effects on the lymph nodes:

The right auricular node was enlarged in 1/5 mice in the highest dose group. As this was a single case, it is not considered to be a sensitivity reaction. No macroscopic abnormalitites were observed in the surrounding area.

Table 1: Individual values for radioactivity measurements (disintegrations per minute) and mean stimulation indices

Group	Animal No.	Concentration (% w/w)	DPM/animal	Stimulation index (mean± SEM)
1	1	0	480	-
	2	0	629	-
	3	0	367	-
	4	0	447	-
	5	0	515	-
Mean ± SEM			488 ± 43	1.0 ± 0.1
2	6	25	514	-
	7	25	516	-
	8	25	519	-
	9	25	817	-
	10	25	491	-
Mean ± SEM			571 ± 62	1.2 ± 0.2
3	11	50	928	-
	12	50	778	-
	13	50	589	-
	14	50	1084	-
	15	50	1376	-
Mean ± SEM			951 ± 134	1.0 ± 0.3
4	16	100	637	-
	17	100	796	-
	18	100	1137	-
	19	100	1013	-
	20	100	1483	-
Mean ± SEM			1013 ± 146	1.1 ± 0.1

DPM = disintegrations per minute

SEM = standard error of the mean

Skin irritation effects:

Slight erythema was observed at the test site on both ears in 5/5 mice exposed to 100% test substance. This was not considered to have affected the activity of the lymph nodes.

Systemic effects:

There was no mortality. No clinical signs were observed during the study period and there were no effects on body weight.

Interpretation of results:

other: CLP/EU GHS criteria not met, no classification required according to Regulation (EC) No 1272/2008.

Reference 3

Endpoint:

skin sensitisation: in vitro

Type of information:

experimental study

Adequacy of study:

weight of evidence

Reliability:

2 (reliable with restrictions)

Rationale for reliability incl. deficiencies:

study well documented, meets generally accepted scientific principles, acceptable for assessment

Remarks:

no details on test substance identity and test results (cell viability, DV-value)

Qualifier:

according to guideline

Guideline:

other: Genomic Allergen Rapid Detection assay (GARDskin)

Version / remarks:

Formal validation of GARDskin and test guideline acceptance is expected in Q2 2019.

Deviations:

not applicable

GLP compliance:

no

Remarks:

Under a GLP-like quality system performed, where instruments and equipment are calibrated and maintained according to the supplier, a strict protocol is followed, QC criteria are met and notes and raw data is archived in paper or electronic.

Type of study:

activation of dendritic cells

Details on the study design:

TEST METHOD
GARD is based on chemical stimulation of a human myeloid leukemia cell line (SenzaCell), acting as an in vitro model of human Dendritic Cells. The readout of the assay is a transcriptional quantification of the genomic predictors, collectively termed the GARD Prediction Signature (GPS), using Nanostring nCounter technology. Substances are predicted as either Sensitizers or Non-sensitizers by a Support Vector Machine (SVM) model, i.e. a machine learning method that is trained using data collected from cell stimulations with known chemicals.

TEST CELL LINE
- Cell line: human myeloid leukemia cell line (SenzaCell)
- Source: SenzaGen AB1 µM
- Passage No. P4-16 (GARD Input Finder), P6-12 (GARD Main Stimulation)
- Phenotypic quality control: The same day as performing a chemical stimulation, the cells are quality controlled by a phenotypic analysis. This is done to ensure cells are maintained in an inactivated state and to detect phenotypic drift. Phenotypic biomarker expression should be within specified ranges, otherwise the cell batch is discarded.

CELL CULTURE CONDITIONS
- Type and identity of media: MEM/Alpha supplemented with 20%FBS and granulocyte macrophage colony stimulating factor (GMCSF, final concentration: 40 ng/mL)
- Temperature (°C): 37 ± 1
- CO2 (%): 5.0 ± 0.5

TEST MATERIAL EXPOSURE PROCEDURE
1) GARD INPUT FINDER
To determine the GARD INPUT concentration for a test substance, cell stimulations are performed using in-well concentrations ranging from 500 µM to 1 µM in DMSO or water or in another suitable solvent (solvent in-well concentration: 0.1%). Cells were incubated for 24 h with these test substance dilution range, harvested and stained with propidium iodide and then analyzed in a flow cytometer for absolute viability. The relative viability is calculated as follows: Rv = v(s)/v(c)*100 (Rv: Relative Viability of sample in %; v(s): absolute viability of the sample in %; v(c): mean absolute viability of two unstimulated stained control samples in %).
The GARD Input concentration of a test substance is decided according to the following decision tree:
1. Test substances that induce cytotoxicity should be used for GARD Main Stimulation at the concentration that induces 90% Relative viability (Rv90), where an acceptance criterion for each sample is a Relative viability of 84.5%-95.4%. If multiple concentrations fulfill the acceptance criterion, the concentration that yields the relative viability closest to 90% is chosen as the Rv90 value.
2. Test substances that are not cytotoxic (relative viability ≥95.5%) are used for GARD Main Stimulation at 500 μM (in-well concentration).
3. Test substances that are not cytotoxic and not soluble to 500 μM (in-well concentration) are used at the highest soluble in-well concentration.

2) GARD MAIN STIMULATION
- Number of replications: triplicates using three different batches of cells
- Exposure duration: 24 h ± 0.5 h
- Negative Control: DMSO and vehicle of test substance
- Positive Control: p-phenylenediamine (PPD; 75 µM)
- A Quality Control of the relative viability was performed by staining the stimulated cells with propidium iodide and flow cytometry analysis to ensure that the test substance shows the same relative viability as in the GARD Input Finder.

RNA ISOLATION
Stimulated cell samples were treated with TRIzol reagent and then total RNA, including mRNA is isolated using a commercially available kit and reagents (Direct-zol RNA MiniPrep, Zymo Research). RNA concentration is quantified and quality controlled (RNA Integrity Number should be >=8.0).

ENDPOINT MEASUREMENT and DATA ANALYSIS
The endpoint measurement of GARD is the quantification of transcriptional levels of 196 genomic predictors, known as the GARD Prediction Signature (GPS), using the Nanostring nCounter system. The results are analysed with the GARD Data Analysis Application (GDAA) and each test substance can be binary predicted as Sensitiser or Non-Sensitser.

ACCEPTANCE CRITERIA
Test Substance Acceptance Criteria:
1. Each test substance should be soluble in either DMSO or water.
2. Each test substance should have three replicate samples with passed Relative viability Quality Control. If two replicate samples have passed after 5 GARD Main Stimulations, the test substance is considered to have passed this criterion.
3. Each test substance should have ≥ two replicate samples with passed RNA Quality Control.
4. Each test substance should have ≥ two replicate samples with passed Nanostring Quality Control
If these criteria cannot be met for a test substance, the GARD assay needs to be repeated for the specific test substance (including benchmark controls).

GARD Campaign Acceptance Criteria:
1. Each stimulation (i.e. GARD Input Finder or GARD Main Stimulation) should be performed with SenzaCells that have passed the Phenotypic Quality Control.
2. The unstimulated cells should have ≥ three replicate samples with passed Absolute viability, RNA and Nanostring Quality Control.
3. Each positive/negative control should have ≥ two replicate samples with passed Relative viability, RNA and Nanostring Quality Control.
4. The positive and negative (DMSO) controls should be accurately classified as Sensitizer and Non-sensitizer, respectively.
If these criteria cannot be met, the GARD assay needs to be repeated for all test substances and controls.


PREDICTION MODEL
For binary predictions, the prediction model is defined as:
If the mean decision value (DV) of biological replicate samples is ≥ 0, the substance is classified as a Sensitizer. If the mean DV of biological replicate samples is < 0, the substance is classified as a Nonsensitizer.

Positive control results:

GARD Skin Decision Value for the positive control p-phenylenediamine predicts the substance as a sensitiser (DV ≥ 0).

Parameter:

other: Decision Value

Value:

0

Vehicle controls validity:

valid

Remarks:

ethanol

Negative controls validity:

valid

Remarks:

DMSO

Positive controls validity:

valid

Remarks on result:

no indication of skin sensitisation

Other effects / acceptance of results:

Ethanol was used as solvent for the test substance.
The test substance was used at a concentration of 500 µM in the GARD Main Stimulation.

Interpretation of results:

other: CLP/EU GHS criteria not met, no classification required according to Regulation (EC) No 1272/2008.

Endpoint conclusion

Endpoint conclusion:

no adverse effect observed (not sensitising)

Additional information:

Skin sensitisation

The skin sensitising potential of Decyl laurate (CAS 36528-28-6) was evaluated in the Genomic Allergen Rapid Detection (GARD) platform (Croda, 2018). In the GARD input finder, the human myeloid leukemia-derived cell line SenzaCell, acting as an in vitro model of human Dendritic Cell, was incubated with the test substance in a dilution range of 1 µM to 500 µM for 24 h. Ethanol was used as the vehicle. No cytotoxicity as determined by propidium iodide staining and flow cytometry was observed. Thus 500 µM test substance was used in the GARD main stimulation. After incubation of the cells for 24 h, cell culture was lysed in a TRIzol reagent and then the RNA was extracted using a commercially available kit. In addition, relative viability was analysed by flow cytometry. A total of 100 ng of RNA was used as the sample input in a hybridization assay with the GPS specific Reporter CodeSet. The hybridized sample was prepared on-chip using nCounter Prep Station and individual transcripts of the GPS (GARD Prediction Signature) were quantified using Nanostring Digital Analyzer. Data analysis revealed a Decision Value (DV) for Decyl laurate of <0 and thus the substance is predicted as a non-sensitiser. In addition to the test substance, a set of positive, negative and vehicle controls were performed as the reference and quality controls and considered as valid.

Analogue justification

The GARD is considered a functional, scientifically validated, but not yet regulatory accepted assay. Therefore, the assessment of skin sensitisation effects of Decyl laurate (CAS 36528-28-6) is also based on studies conducted with analogue substances as part of a read across approach, which is in accordance with Regulation (EC) No. 1907/2006, Annex XI, 1.5. For each specific endpoint the source substance(s) structurally closest to the target substance is/are chosen for read-across, with due regard to the requirements of adequacy and reliability of the available data. Structural similarities and similarities in properties and/or activities of the source and target substance are the basis of read-across. A detailed justification for the analogue read-across approach is provided in the technical dossier (see IUCLID Section 13).

CAS 163961-32-8

A Guinea pig maximisation test (GPMT) was performed with Fatty acids, C16-18 and C18 unsatd. branched and linear, butyl esters (CAS 163961-32-8) under GLP conditions and according to OECD guideline 406 (WoE, 2002). Ten test and 5 control Himalayan guinea pigs were induced intradermally with 1% test substance on both sides of the spine with and without Freud's complete adjuvant. On Day 7, a 48-hour epicutaneous induction treatment with the undiluted test substance was performed under semi-occlusive conditions. On Day 22, the challenge treatment was performed by topical application of the test substance at 50% and 75% to all animals for 24 hours, under semi-occlusive conditions. Skin reactions were evaluated 24 and 48 hours after the challenge application. During the study, no test substance-related clinical signs and no effects on body weight gain were observed. 8 hours after intradermal induction, slight to moderate erythema was noted at all of the sites injected with FCA/water and FCA/test substance in 10/10 treated and 5/5 control animals. 2 hours after the topical induction ended, moderate erythema and staining was observed in 10/10 treated animals and bleeding was observed at the test site in 3/10 treated animals, while 1/5 control animals showed slight erythema. All treated animals still showed slight-moderate erythema 24 hours after removal of the dressing, while the skin irritation effects had cleared completely in the control animals. Mild skin reactions were observed in 1/10 treated animals after the challenge treatment. The results of the reliability check carried out at regular intervals were positive, confirming the reliability of the assay. Based on the results, the test substance had no sensitising effect in guinea pigs under the experimental conditions.

 

CAS 3687-46-5

An in vivo skin sensitisation study (Local Lymph Node Assay, LLNA) was performed with Decyl oleate (CAS 3687-46-5) according to OECD guideline 429 and under GLP conditions (WoE, 2010). Five female CBA/J mice per dose were treated with 0, 25, 50 and 100% of the test substance in acetone/olive oil. The test substance formulations or the vehicle were applied epicutaneously onto the dorsal part of each ear (25 µL/ear) for three consecutive days. All mice were sacrificed three days after the last treatment (on Day 6) and the weight of the lymph nodes was determined. The cell proliferation of pooled lymph nodes from individual animals was measured as 3H-methyl thymidine incorporation and determined by beta-scintillation counting. The stimulation indices were 1.0, 1.2, 2.0 and 2.1 for the control, 25, 50 and 100% groups, respectively. The SI slightly increased with the dose level, but the increase was not statistically significant. Positive and vehicle controls were valid. An EC3 value of the test substance could not be calculated, as all stimulation indices were <3. Based on the study results, the test substance was not skin sensitising.

 

Conclusion

Decyl laurate (CAS 36528-28-6) is predicted as a non-sensitiser in the GARD assay. Furthermore, no sensitising potential was seen in experimental studies in mice (LLNA) and guinea pigs (GPMT) performed with source substances. Based on the available information, Decyl laurate is not expected to be skin sensitising.

Respiratory sensitisation

Endpoint conclusion

Endpoint conclusion:

no study available

Justification for classification or non-classification

According to Article 13 of Regulation (EC) No. 1907/2006 "General Requirements for Generation of Information on Intrinsic Properties of substances", information on intrinsic properties of substances may be generated by means other than tests e.g. from information from structurally related substances (grouping or read-across), provided that conditions set out in Annex XI are met. Annex XI, "General rules for adaptation of this standard testing regime set out in Annexes VII to X” states that “substances whose physicochemical, toxicological and ecotoxicological properties are likely to be similar or follow a regular pattern as a result of structural similarity may be considered as a group, or ‘category’ of substances. This avoids the need to test every substance for every endpoint". Since the analogue concept is applied to Decyl laurate (CAS 36528-28-6), data will be generated from data for reference source substance(s) to avoid unnecessary animal testing. Additionally, once the analogue read-across concept is applied, substances will be classified and labelled on this basis.

The available data on skin sensitisation do not meet the classification criteria according to Regulation (EC) 1272/2008 or Directive 67/548/EEC, and are therefore conclusive but not sufficient for classification.