Registration Dossier

Diss Factsheets

Administrative data

Description of key information

QSAR: not sensitising

In vivo (LLNA, read across): not sensitising

In vivo (GPMT, read across): not sensitising

Key value for chemical safety assessment

Skin sensitisation

Link to relevant study records

Referenceopen allclose all

Endpoint:
skin sensitisation, other
Type of information:
(Q)SAR
Adequacy of study:
supporting study
Reliability:
2 (reliable with restrictions)
Rationale for reliability incl. deficiencies:
results derived from a valid (Q)SAR model and falling into its applicability domain, with adequate and reliable documentation / justification
Justification for type of information:
1. SOFTWARE
The OECD QSAR Toolbox v3.4 is a Quantitative Structure-Activity Relationship model that was developed by the Laboratory of Mathematical Chemistry (http://toolbox.oasis-lmc.org).
2. MODEL (incl. version number)
OECD QSAR Toolbox version 3.4
3. SMILES OR OTHER IDENTIFIERS USED AS INPUT FOR THE MODEL
The SMILES code for the test substance was used.
4. SCIENTIFIC VALIDITY OF THE (Q)SAR MODEL
- Defined endpoint: The model was used to predict the in vivo skin sensitisation potential of the test substance using the option 'Skin sensitisation (Danish EPA database)'. The results from this model are based on the Danish (Q)SAR Database, developed by the Danish Environmental Protection Agency (EPA). The (Q)SAR database comprises predictions made by some 70 models for about 166,000 organic chemicals for a wide range of different endpoints. In 2004, a collaborative project was set up between the Danish EPA and the ECB to develop an internet-accessible version of the database, which was also incorporated in the OECD QSAR Toolbox. This version of the Danish (Q)SAR Database was constructed to enable different types of searching, including structure (substructure/exact match) searching, ID (CAS number, name) searching and parameter (endpoint) searching, specifically for skin sensitisation potential. See report attached under 'Attached background material'.
- Short description of test conditions: The SMILES code of the test substance is compared with substances in the database, for which the (lack of) skin sensitising potential is known.
- Parameters analysed / observed: A QSAR prediction of the skin sensitisation potential of the main constituent(s) of the test substance was performed by comparing them with the substances in the 'Skin sensitisation (Danish EPA database)'.
- Unambiguous algorithm: Prediction approach: prediction from existing (Q)SAR model; calculation approach: SAR/(Q)SAR prediction; model name: Skin sensitisation (Danish EPA DB); predicted value: negative.
- Defined domain of applicability: Predictions and domain results are pre-calculated and stored in the database.
5. APPLICABILITY DOMAIN
- Descriptor domain: The target chemical falls within the applicability domain of the prediction. Predictions and domain results are pre-calculated and stored in the database.
6. ADEQUACY OF THE RESULT
The results may be used in a weight-of-evidence approach together with other information to reach a conclusion regarding the skin sensitising potential of the test substance.
Guideline:
other: Practical guide How to use and report (Q)SARs
Version / remarks:
2016, ECHA-16-B-09-EN
Principles of method if other than guideline:
- Principle of test: The OECD QSAR Toolbox v3.4 is a Quantitative Structure-Activity Relationship model that was developed by the Laboratory of Mathematical Chemistry (http://toolbox.oasis-lmc.org). It contains several different databases with data on chemicals. The model was used to predict the skin sensitisation potential of the main constituent(s) of the test substance using the option 'Skin sensitisation (Danish EPA database)'. The results from this model are based on the Danish (Q)SAR Database, developed by the Danish Environmental Protection Agency (EPA). The (Q)SAR database comprises predictions made by some 70 models for about 166,000 organic chemicals for a wide range of different endpoints. In 2004, a collaborative project was set up between the Danish EPA and the ECB to develop an internet-accessible version of the database, which was also incorporated in the OECD QSAR Toolbox. This version of the Danish (Q)SAR Database was constructed to enable different types of searching, including structure (substructure/exact match) searching, ID (CAS number, name) searching and parameter (endpoint) searching, specifically for skin sensitisation potential.
- Short description of test conditions: The SMILES code of the main constituents of the test substance is compared with substances in the database, for which the (lack of) skin sensitising potential is known.
- Parameters analysed / observed: A QSAR prediction of the skin sensitisation potential of the main constituent(s) of the test substance was performed by comparing them with the substances in the 'Skin sensitisation (Danish EPA database)'.
GLP compliance:
no

The predicted skin sensitisation potential of hexadecanoic acid, hexadecyl ester was modelled in the OECD QSAR Toolbox v3.4. The test substance falls within the model applicability domain for the database 'Skin sensitisation (Danish EPA DB)'. The result of the prediction was negative.

Therefore, hexadecanoic acid, hexadecyl ester is not expected to have a skin sensitising potential.

Interpretation of results:
other: The prediction results was negative for skin sensitising potential, based on QSAR prediction (OECD QSAR Toolbox v3.4, Danish EPA database). The results may only be used for classification purposes together with other data in a weight-of-evidence approach.
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.
Endpoint:
skin sensitisation: in vivo (non-LLNA)
Type of information:
experimental study
Adequacy of study:
weight of evidence
Study period:
24 Mar - 24 Apr 1998
Reliability:
2 (reliable with restrictions)
Rationale for reliability incl. deficiencies:
guideline study with acceptable restrictions
Remarks:
The epicutaneous induction and challenge were performed under semi-occlusive conditions.
Qualifier:
according to guideline
Guideline:
OECD Guideline 406 (Skin Sensitisation)
Deviations:
yes
Remarks:
epicutaneous induction and challenge performed under semi-occlusive conditions
Qualifier:
according to guideline
Guideline:
EU Method B.6 (Skin Sensitisation)
Deviations:
yes
Remarks:
epicutaneous induction and challenge performed under semi-occlusive conditions
GLP compliance:
yes
Type of study:
guinea pig maximisation test
Justification for non-LLNA method:
There is data available for an in vivo Guinea Pig Maximisation Test that was performed prior to the amendment to Regulation (EC) No 1097/2006 stating the LLNA is the first-choice in vivo study.
Species:
guinea pig
Strain:
Himalayan
Sex:
female
Details on test animals and environmental conditions:
TEST ANIMALS
- Source: BRL Ltd., Basel, Switzerland
- Age at study initiation: approximately 6 weeks
- Weight at study initiation: 416 ± 23 g (mean ± SD, control group); 434 ± 24 g (mean ± SD, treatment group)
- Housing: animals were housed in groups of 5 in labelled metal cages with wire-mesh floors (ITL, Bergen, the Netherlands)
- Diet: standard guinea pig diet (LC 23-B, pellet diameter 4mm, including ascorbic acid (1600 mg/kg); Hope farms, Woerden, the Netherlands), ad libitum
- Water: tap water, ad libitum
- Acclimation period: at least 5 days

ENVIRONMENTAL CONDITIONS
- Temperature (°C): 21
- Humidity (%): 50
- Air changes (per hr): approximately 15
- Photoperiod (hrs dark / hrs light): 12/12

IN-LIFE DATES: From: 24 March 1998 To: 24 April 1998
Route:
intradermal
Vehicle:
unchanged (no vehicle)
Concentration / amount:
100%
Day(s)/duration:
Day 1
Adequacy of induction:
highest technically applicable concentration used
Route:
epicutaneous, semiocclusive
Vehicle:
unchanged (no vehicle)
Concentration / amount:
100%
Day(s)/duration:
Day 8
Adequacy of induction:
non-irritant substance, but skin pre-treated with 10% SDS
No.:
#1
Route:
epicutaneous, semiocclusive
Vehicle:
unchanged (no vehicle)
Concentration / amount:
1005
Day(s)/duration:
Day 21
Adequacy of challenge:
highest non-irritant concentration
No. of animals per dose:
10 (treatment group)
5 (control group)
Details on study design:
RANGE FINDING TESTS:
Prior to the start of the main study, the intradermal and epidermal irritancy of the test substance was investigated to select suitable concentrations for the induction and challenge phase of the main study. The selection was based on the absence of toxicity and on the following criteria for each route and/or study phase:
Induction (intradermal and epidermal): The highest possible concentration that produced moderate irritation (the intradermal reactions may include slight necrosis (< 3 mm in diameter)).
Challenge: The maximum non-irritant concentration.

A series of test substance concentrations were tested. The first and subsequent concentrations were selected from the series: 100% (undiluted), 50%, 20%, 10%, 5%, 2%, 1% and if needed, further lower concentrations using the same steps. The test system and procedures were identical to those used during the main study, unless otherwise specified. The four animals were 5-9 weeks old. The body weights were determined prior to treatment (results not shown).

Intradermal Injections:
A series of four test substance concentrations was used; the highest concentration was the maximum concentration that could technically be
injected (undiluted). One animal received 50 and 100% (undiluted), and the second animal received 10 and 20%, respectively, in duplicate (0.1 mL/site) in the clipped scapular region. The injection sites were assessed for irritation 24 and 48 hours after treatment. Slight erythema was observed at the injection site of the undiluted test substance 48 h after exposure. The udiluted test substance was selected for the induction phase in the main study.

Epidermal application:
A series of four test substance concentrations (10, 20, 50 and 100%) was used. All concentrations could technically be applied. Two different concentrations were applied (0.5 mL each) per animal to the clipped flank, using Metalline patches (2x3 cm) mounted on Medical tape, which were held in place with Micropore tape and subsequently Coban elastic bandage (semi-occlusive covering). The animals receiving intradermal injections were treated with the lowest concentrations (10 and 20%) and two further animals with the highest concentrations (50 and 100%). After 24 hours, the dressing was removed and the skin cleaned of residual test substance. The treated skin areas were assessed for irritation 24 and 48 hours after exposure. No skin irritation was observed at any of the treated sites at any of the reading time points. As the epidermal induction using the test substance did not cause any skin irritation, the test site of all animals was treated with 10% SDS approximately 24 hours before the epidermal induction in the main study, to provoke a mild inflammatory reaction. The udiluted test substance was selected for the challenge phase in the main study.

MAIN STUDY
A. INDUCTION EXPOSURE
- No. of exposures: 2, intradermal and epicutaneous
- Exposure period: single injection (epidermal) and 48 h (epicutaneous)
- Test groups:
Intradermal, Day 1 (3 pairs of injections, 0.1 mL/site):
Injection 1: a 1:1 mixture (w/w) Freunds Complete Adjuvant (FCA)/water for injection
Injection 2: undiluted test substance
Injection 3: undiluted test substance in a 1:1 mixture (w/w) with FCA (final concentration is 50% test substance)
48 h after intradermal injection (Day 3), the degree of erythema and edema was evaluated.

On Day 7, the scapular area between the injection sites was clipped and subsequently rubbed with 10% sodium dodecyl sulfate in vaseline using a spatula. This concentration of SDS provoked a mild inflammatory reaction.

Epicutaneous, Day 8:
0.5 mL undiluted test substance was applied to the SDS-treated skin area. The semi-occlusive dressing was kept in place for 48 h. The degree of erythema and edema was evaluated directly after cleaning the skin area with water (Day 10).

- Control group:
Intradermal, day 1 (3 pairs of injections, 0.1 mL/site):
Injection 1: a 1:1 mixture (w/w) FCA/water
Injection 2: corn oil
Injection 3: corn oil (w/v) in a 1:1 mixture (w/w) FCA (final concentration is 50% corn oil)

On Day 7, the scapular area between the injection sites was clipped and subsequently rubbed with 10% sodium dodecyl sulfate (SDS, Boom, Meppel, the Netherlands) in vaseline using a spatula. This concentration of SDS provoked a mild inflammatory reaction.

Epicutaneous, Day 8: 0.5 mL corn oil

- Site: the shoulder region
- Frequency of applications: once (intradermal on Day 1 and epicutaneous on Day 8)
- Duration: Day 1 (intradermal), Day 8-10 (epicutaneous)
- Concentrations: undiluted (intradermal and epicutaneous)

B. CHALLENGE EXPOSURE
- No. of exposures: 1 (challenge)
- Day(s) of challenge: 21
- Exposure period: 24 hours
- Test groups: 0.5 mL test substance
- Control group: 0.5 mL test substance
- Site: approximately 20 mm x 30 mm, on one flank of the animals
- Concentration: undiluted
- Evaluation (hr after challenge): 24 and 48 hours after the challenge ended
Positive control substance(s):
yes
Remarks:
alpha-hexylcinnamicaldehyde, tech. 85%
Positive control results:
A reliability check is carried out at regular intervals with alpha-hexylcinnamic aldehyde to check the sensitivity of the test system and the reliability of the experimental methods used by the test laboratory. In an independent study performed in 1998 (report No. 217812), alpha-hexylcinnamic aldehyde induced sensitisation in 80% (8/10) of the Himalayan guinea pigs challenged with a 10% solution, and in 70% (7/10) of the guinea pigs challenged with a 5% solution. A 5% solution was used for intradermal induction and undiluted test substance was used for topical induction.
Key result
Reading:
1st reading
Hours after challenge:
24
Group:
negative control
Dose level:
undiluted
No. with + reactions:
0
Total no. in group:
5
Remarks on result:
other: Reading: 1st reading. . Hours after challenge: 24.0. Group: negative control. Dose level: undiluted. No with. + reactions: 0.0. Total no. in groups: 5.0.
Key result
Reading:
1st reading
Hours after challenge:
24
Group:
test chemical
Dose level:
undiluted
No. with + reactions:
0
Total no. in group:
10
Remarks on result:
other: Reading: 1st reading. . Hours after challenge: 24.0. Group: test group. Dose level: undiluted. No with. + reactions: 0.0. Total no. in groups: 10.0.
Key result
Reading:
2nd reading
Hours after challenge:
48
Group:
negative control
Dose level:
undiluted
No. with + reactions:
0
Total no. in group:
5
Remarks on result:
other: Reading: 2nd reading. . Hours after challenge: 48.0. Group: negative control. Dose level: undiluted. No with. + reactions: 0.0. Total no. in groups: 5.0.
Key result
Reading:
2nd reading
Hours after challenge:
48
Group:
test chemical
Dose level:
undiluted
No. with + reactions:
0
Total no. in group:
10
Remarks on result:
other: Reading: 2nd reading. . Hours after challenge: 48.0. Group: test group. Dose level: undiluted. No with. + reactions: 0.0. Total no. in groups: 10.0.

48 hours after intradermal induction, slight to severe 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. 4/5 control animals also exhibited necrosis at the FCA/test substance injection site. In 3/10 treated animals slight to well-defined erythema was observed at the injection site of the test substance. Following the topical induction, severe erythema and scabs were observed at the test site in 3/10 treated animals. A further 4/10 (in total 7/10) treated and 4/5 control animals exhibited only scabs. No edema was observed (see Table 1).

48 and 72 hours after the challenge, no sensitisation was observed in the treated animals.

There was no mortality, no signs of toxicity and no treatment-related effects on body weight.

Table 1: skin irritation effects of intradermal and epidermal induction

 

Group/

animal No.

Intradermal induction (Day 3), undiluted test substance

Epidermal induction (Day 10), undiluted test substance

Control

A

B

C

Erythema

Edema

16

E2

NA

E3

0p

0

17

E2

NA

N2

0a

0

18

E3

NA

N3

0a

0

19

E3

NA

N3

0

0

20

E2

NA

N3

0a

0

Experimental

 

 

 

 

 

21

E4

NA

E2

0a

0

22

E1

NA

E1

0

0

23

E2

E2

E2

0a

0

24

E2

NA

E1

0a

0

25

E1

NA

E1

4k

0

26

E1

NA

E1

0

0

27

E3

E1

E2

0a

0

28

E2

E1

E2

4s

0

29

E2

NA

E2

4k

0

30

E3

NA

E2

0

0

A. 1:1 mixture of FCA and water for injection

B. undiluted test substance (experimental group) or vehicle (control group)

C. 1:1 mixture of FCA and undiluted test substance (experimental group) or vehicle (control group)

a. small scabs

k. scabs

p. scaliness

s. eschar formation

 

Skin effect intradermal injections:

NA. No abnormalities

E. erythema

N. signs of necrosis (mm in diameter)

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:

Justification for read-across

There are noin vitroorin vivodata on the skin sensitisation potential of Hexadecyl palmitate (CAS 540-10-3). The assessment was therefore performed as a weight-of-evidence approach based on QSAR modelling and studies performed with analogue (source) 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).

QSAR predictions

CAS 540-10-3

The skin sensitising potential of Hexadecyl palmitate (CAS 540-10-3) was predicted in the QSAR OECD Toolbox v3.4 (WoE, 2017). The test substance falls within the model applicability domain for the database 'Skin sensitisation (Danish EPA DB)'. The result of the prediction was negative, no skin sensitising potential was predicted.

Animal data

CAS 93803-87-3

A Guinea pig maximisation test (GPMT) was performed with 2-octyldodecyl isooctadecanoate (CAS 93803-87-3) under GLP conditions and according to OECD guideline 406 (WoE, 1998). Ten test and 5 control Himalayan guinea pigs were induced intradermally with undiluted test substance on both sides of the spine with and without Freud's complete adjuvant. On Day 7, the animals were treated with 10% sodium dodecyl sulfate to induce mild skin irritation. On Day 8, 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 100% (right flank) and a blank patch (left flank) 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 severe 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. 4/5 control animals also exhibited necrosis at the FCA/test substance injection site. In 3/10 treated animals slight to well-defined erythema was observed at the injection site of the test substance. Following the topical induction, severe erythema and scabs were observed at the test site in 3/10 treated animals. A further 4/10 (in total 7/10) treated and 4/5 control animals exhibited only scabs. No skin reactions were observed after the challenge treatment in any of the animals of the test and control groups. 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.

Overall conclusion for skin sensitisation

The OECD QSAR Toolbox did not predict skin sensitising properties of the target substance. No sensitising potential was seen in experimental studies in mice (LLNA) and guinea pigs (GPMT) performed with source substances. Based on the available information, Hexadecyl palmitate (CAS 540-10-3) 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 Hexadecyl palmitate (CAS 540-10-3), 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.

Therefore, based on the analogue read-across approach, the available data on skin sensitisation do not meet the classification criteria according to Regulation (EC) 1272/2008, and are therefore conclusive but not sufficient for classification.