Fatty acids, C8-10, C8-10-alkyl esters

Endpoint summary

Description of key information

Based on a weight-of-evidence assessment of the available data (read-across), the substance is considered to be not skin sensitising.

Key value for chemical safety assessment

Skin sensitisation

Link to relevant study records

Reference

Reference 1

Endpoint:

skin sensitisation, other

Type of information:

(Q)SAR

Adequacy of study:

weight of evidence

Reliability:

2 (reliable with restrictions)

Rationale for reliability incl. deficiencies:

other: Accepted QSAR model

Justification for type of information:

The OECD QSAR Toolbox v3.3 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 test substance. One of the necessary steps for a substance to cause skin sensitisation is the formation of a stable association with a skin protein. This is most likely to be covalent association between the test substance (electrophile) and the skin protein (nucleophile). The Toolbox is used to identify structural alerts, like chemical groups, in the test substance that may indicate a protein binding potential.
The test substance was run against the following databases: Protein binding by OASIS v1.3; Protein binding by OECD; Protein binding potency; Protein binding alerts for skin sensitisation by OASIS v1.3.
For the Protein binding alerts for skin sensitisation by OASIS v1.3, the following reaction mechanisms were considered:
-Acylation (acyl transfer via nucleophilic addition reaction; direct acylation involving a leaving group; ester aminolysis; ester aminolysis or thiolysis; isocyanates and related chemicals; ring opening acylation).
-Ionic interaction (electrostatic interaction of tetraalkylammonium ion with protein carboxylates; substituted guanidines).
-Michael addition (α, β-unsaturated carbonyl compounds; addition on conjugated systems with electron withdrawing group; addition on azoxy compounds; addition on phosphoranylidene compounds; addition on unsaturated sultones; polarised alkenes; polarised alkynes; polarised azo compounds; quinoide type compounds; quinone type chemicals).
-Nucleophilic addition (addition to carbon-hetero double bonds, addition reaction at polarised N-functional double bond).
-Radical reactions (free radical formation).
-Schiff base formation (benzoyl formation; direct acting Schiff base formers; pyrazolones and pyrazolidinones derivatives; formation with carbonyl compounds).
-SN1 (carbenium ion formation – enzymatic; nucleophilic substitution SN1 on alkyl or aryl mercury cations).
-SN2 (activated allyl type fragment; interchange reaction with sulphur containing compounds; nucleophilic substitution at a nitrogen atom; nucleophilic substitution at sp3 carbon atom; nucleophilic substitution at the central carbon atom of N-nitroso compounds; nucleophilic substitution on a sulphur atom; nucleophilic substitution on benzylic carbon atom; nucleophilic substitution on heteroarene sulfenamides; protein azidation via an SN2-like reaction; ring opening SN2 reaction; reaction at a halo atom; reaction at a sp2 carbon atom; reaction at a sp3 carbon atom; reaction at a sulfur atom).
-SN2 ionic (nucleophilic substitution at protein disulphide bonds involving O- or S- nucleophiles).
-SNAr (nucleophilic aromatic substitution on activated aryl and heteroaryl compounds; nucleophilic aromatic substitution on activated halogen, cyano, isocyano, sulfo, sulfonyl groups; nucleophilic aromatic substitution on halogenated nitrophenols).
-SNVinyl (nucleophilic vinylic substitution on activated halogens; SNVinyl at a vinylic (sp2) carbon atom).

Principles of method if other than guideline:

Calculation based on OECD QSAR Toolbox v3.3. QSAR prediction of the skin sensitisation potential of the test substance. The potential for protein binding and the presence of structural alerts that may indicate a skin sensitising potential are assessed.

Key result

Parameter:

other: OECD QSAR Toolbox profiling

Remarks on result:

other: No structural alerts identified.

The predicted skin sensitisation potential of the C10/C10 component of Fatty acids, C8 -10, C8 -10 alkyl esters was modelled in the OECD QSAR Toolbox. The test substance falls within the model applicability domain for the databases: Protein binding by OASIS v1.3; Protein binding by OECD; Protein binding potency; Protein binding alerts for skin sensitisation by OASIS v1.3; No structural alerts were found.

Therefore, the C10/C10 component of Fatty acids, C8 -10, C8 -10 alkyl esters is not expected to have a skin sensitising potential.

Interpretation of results:

other: not predicted to have skin sensitising potential

Reference 2

Endpoint:

skin sensitisation, other

Type of information:

(Q)SAR

Adequacy of study:

weight of evidence

Reliability:

2 (reliable with restrictions)

Rationale for reliability incl. deficiencies:

other: Accepted QSAR model

Justification for type of information:

QSAR prediction: The OECD QSAR Toolbox v3.3 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 test substance. One of the necessary steps for a substance to cause skin sensitisation is the formation of a stable association with a skin protein. This is most likely to be covalent association between the test substance (electrophile) and the skin protein (nucleophile). The Toolbox is used to identify structural alerts, like chemical groups, in the test substance that may indicate a protein binding potential.
The test substance was run against the following databases: Protein binding by OASIS v1.3; Protein binding by OECD; Protein binding potency; Protein binding alerts for skin sensitisation by OASIS v1.3.
For the Protein binding alerts for skin sensitisation by OASIS v1.3, the following reaction mechanisms were considered:
-Acylation (acyl transfer via nucleophilic addition reaction; direct acylation involving a leaving group; ester aminolysis; ester aminolysis or thiolysis; isocyanates and related chemicals; ring opening acylation).
-Ionic interaction (electrostatic interaction of tetraalkylammonium ion with protein carboxylates; substituted guanidines).
-Michael addition (α, β-unsaturated carbonyl compounds; addition on conjugated systems with electron withdrawing group; addition on azoxy compounds; addition on phosphoranylidene compounds; addition on unsaturated sultones; polarised alkenes; polarised alkynes; polarised azo compounds; quinoide type compounds; quinone type chemicals).
-Nucleophilic addition (addition to carbon-hetero double bonds, addition reaction at polarised N-functional double bond).
-Radical reactions (free radical formation).
-Schiff base formation (benzoyl formation; direct acting Schiff base formers; pyrazolones and pyrazolidinones derivatives; formation with carbonyl compounds).
-SN1 (carbenium ion formation – enzymatic; nucleophilic substitution SN1 on alkyl or aryl mercury cations).
-SN2 (activated allyl type fragment; interchange reaction with sulphur containing compounds; nucleophilic substitution at a nitrogen atom; nucleophilic substitution at sp3 carbon atom; nucleophilic substitution at the central carbon atom of N-nitroso compounds; nucleophilic substitution on a sulphur atom; nucleophilic substitution on benzylic carbon atom; nucleophilic substitution on heteroarene sulfenamides; protein azidation via an SN2-like reaction; ring opening SN2 reaction; reaction at a halo atom; reaction at a sp2 carbon atom; reaction at a sp3 carbon atom; reaction at a sulfur atom).
-SN2 ionic (nucleophilic substitution at protein disulphide bonds involving O- or S- nucleophiles).
-SNAr (nucleophilic aromatic substitution on activated aryl and heteroaryl compounds; nucleophilic aromatic substitution on activated halogen, cyano, isocyano, sulfo, sulfonyl groups; nucleophilic aromatic substitution on halogenated nitrophenols).
-SNVinyl (nucleophilic vinylic substitution on activated halogens; SNVinyl at a vinylic (sp2) carbon atom).

Principles of method if other than guideline:

Calculation based on OECD QSAR Toolbox v3.3. QSAR prediction of the skin sensitisation potential of the test substance. The potential for protein binding and the presence of structural alerts that may indicate a skin sensitising potential are assessed.

Key result

Parameter:

other: OECD QSAR Toolbox profiling

Remarks on result:

other: No structural alerts identified.

The predicted skin sensitisation potential of the C10/C8 component of Fatty acids, C8 -10, C8 -10 alkyl esters was modelled in the OECD QSAR Toolbox. The test substance falls within the model applicability domain for the databases: Protein binding by OASIS v1.3; Protein binding by OECD; Protein binding potency; Protein binding alerts for skin sensitisation by OASIS v1.3; No structural alerts were found.

Therefore, the C10/C8 component of Fatty acids, C8 -10, C8 -10 alkyl esters is not expected to have a skin sensitising potential.

Interpretation of results:

other: not predicted to have skin sensitising potential

Reference 3

Endpoint:

skin sensitisation, other

Type of information:

(Q)SAR

Adequacy of study:

weight of evidence

Reliability:

2 (reliable with restrictions)

Rationale for reliability incl. deficiencies:

other: Accepted QSAR model

Justification for type of information:

QSAR prediction: The OECD QSAR Toolbox v3.3 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 test substance. One of the necessary steps for a substance to cause skin sensitisation is the formation of a stable association with a skin protein. This is most likely to be covalent association between the test substance (electrophile) and the skin protein (nucleophile). The Toolbox is used to identify structural alerts, like chemical groups, in the test substance that may indicate a protein binding potential.
The test substance was run against the following databases: Protein binding by OASIS v1.3; Protein binding by OECD; Protein binding potency; Protein binding alerts for skin sensitisation by OASIS v1.3.
For the Protein binding alerts for skin sensitisation by OASIS v1.3, the following reaction mechanisms were considered:
-Acylation (acyl transfer via nucleophilic addition reaction; direct acylation involving a leaving group; ester aminolysis; ester aminolysis or thiolysis; isocyanates and related chemicals; ring opening acylation).
-Ionic interaction (electrostatic interaction of tetraalkylammonium ion with protein carboxylates; substituted guanidines).
-Michael addition (α, β-unsaturated carbonyl compounds; addition on conjugated systems with electron withdrawing group; addition on azoxy compounds; addition on phosphoranylidene compounds; addition on unsaturated sultones; polarised alkenes; polarised alkynes; polarised azo compounds; quinoide type compounds; quinone type chemicals).
-Nucleophilic addition (addition to carbon-hetero double bonds, addition reaction at polarised N-functional double bond).
-Radical reactions (free radical formation).
-Schiff base formation (benzoyl formation; direct acting Schiff base formers; pyrazolones and pyrazolidinones derivatives; formation with carbonyl compounds).
-SN1 (carbenium ion formation – enzymatic; nucleophilic substitution SN1 on alkyl or aryl mercury cations).
-SN2 (activated allyl type fragment; interchange reaction with sulphur containing compounds; nucleophilic substitution at a nitrogen atom; nucleophilic substitution at sp3 carbon atom; nucleophilic substitution at the central carbon atom of N-nitroso compounds; nucleophilic substitution on a sulphur atom; nucleophilic substitution on benzylic carbon atom; nucleophilic substitution on heteroarene sulfenamides; protein azidation via an SN2-like reaction; ring opening SN2 reaction; reaction at a halo atom; reaction at a sp2 carbon atom; reaction at a sp3 carbon atom; reaction at a sulfur atom).
-SN2 ionic (nucleophilic substitution at protein disulphide bonds involving O- or S- nucleophiles).
-SNAr (nucleophilic aromatic substitution on activated aryl and heteroaryl compounds; nucleophilic aromatic substitution on activated halogen, cyano, isocyano, sulfo, sulfonyl groups; nucleophilic aromatic substitution on halogenated nitrophenols).
-SNVinyl (nucleophilic vinylic substitution on activated halogens; SNVinyl at a vinylic (sp2) carbon atom).

Principles of method if other than guideline:

Calculation based on OECD QSAR Toolbox v3.3. QSAR prediction of the skin sensitisation potential of the test substance. The potential for protein binding and the presence of structural alerts that may indicate a skin sensitising potential are assessed.

Key result

Parameter:

other: OECD QSAR Toolbox profiling

Remarks on result:

other: No structural alerts identified.

The predicted skin sensitisation potential of the C8/C10 component of Fatty acids, C8 -10, C8 -10 alkyl esters was modelled in the OECD QSAR Toolbox. The test substance falls within the model applicability domain for the databases: Protein binding by OASIS v1.3; Protein binding by OECD; Protein binding potency; Protein binding alerts for skin sensitisation by OASIS v1.3. No structural alerts were found.

Therefore, the C8/C10 component of Fatty acids, C8-10, C8-10 alkyl esters is not expected to have a skin sensitising potential.

Interpretation of results:

other: not predicted to have skin sensitising potential

Reference 4

Endpoint:

skin sensitisation, other

Type of information:

(Q)SAR

Adequacy of study:

weight of evidence

Reliability:

2 (reliable with restrictions)

Rationale for reliability incl. deficiencies:

other: Accepted QSAR model

Justification for type of information:

The OECD QSAR Toolbox v3.3 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 test substance. One of the necessary steps for a substance to cause skin sensitisation is the formation of a stable association with a skin protein. This is most likely to be covalent association between the test substance (electrophile) and the skin protein (nucleophile). The Toolbox is used to identify structural alerts, like chemical groups, in the test substance that may indicate a protein binding potential.
The test substance was run against the following databases: Protein binding by OASIS v1.3; Protein binding by OECD; Protein binding potency; Protein binding alerts for skin sensitisation by OASIS v1.3.
For the Protein binding alerts for skin sensitisation by OASIS v1.3, the following reaction mechanisms were considered:
-Acylation (acyl transfer via nucleophilic addition reaction; direct acylation involving a leaving group; ester aminolysis; ester aminolysis or thiolysis; isocyanates and related chemicals; ring opening acylation).
-Ionic interaction (electrostatic interaction of tetraalkylammonium ion with protein carboxylates; substituted guanidines).
-Michael addition (α, β-unsaturated carbonyl compounds; addition on conjugated systems with electron withdrawing group; addition on azoxy compounds; addition on phosphoranylidene compounds; addition on unsaturated sultones; polarised alkenes; polarised alkynes; polarised azo compounds; quinoide type compounds; quinone type chemicals).
-Nucleophilic addition (addition to carbon-hetero double bonds, addition reaction at polarised N-functional double bond).
-Radical reactions (free radical formation).
-Schiff base formation (benzoyl formation; direct acting Schiff base formers; pyrazolones and pyrazolidinones derivatives; formation with carbonyl compounds).
-SN1 (carbenium ion formation – enzymatic; nucleophilic substitution SN1 on alkyl or aryl mercury cations).
-SN2 (activated allyl type fragment; interchange reaction with sulphur containing compounds; nucleophilic substitution at a nitrogen atom; nucleophilic substitution at sp3 carbon atom; nucleophilic substitution at the central carbon atom of N-nitroso compounds; nucleophilic substitution on a sulphur atom; nucleophilic substitution on benzylic carbon atom; nucleophilic substitution on heteroarene sulfenamides; protein azidation via an SN2-like reaction; ring opening SN2 reaction; reaction at a halo atom; reaction at a sp2 carbon atom; reaction at a sp3 carbon atom; reaction at a sulfur atom).
-SN2 ionic (nucleophilic substitution at protein disulphide bonds involving O- or S- nucleophiles).
-SNAr (nucleophilic aromatic substitution on activated aryl and heteroaryl compounds; nucleophilic aromatic substitution on activated halogen, cyano, isocyano, sulfo, sulfonyl groups; nucleophilic aromatic substitution on halogenated nitrophenols).
-SNVinyl (nucleophilic vinylic substitution on activated halogens; SNVinyl at a vinylic (sp2) carbon atom).

Principles of method if other than guideline:

Calculation based on OECD QSAR Toolbox v3.3. QSAR prediction of the skin sensitisation potential of the test substance. The potential for protein binding and the presence of structural alerts that may indicate a skin sensitising potential are assessed.

Key result

Parameter:

other: OECD QSAR Toolbox profiling

Remarks on result:

other: No structural alerts identified.

The predicted skin sensitisation potential of the C8/C8 component of Fatty acids, C8 -10, C8 -10 alkyl esters was modelled in the OECD QSAR Toolbox. The test substance falls within the model applicability domain for the databases: Protein binding by OASIS v1.3; Protein binding by OECD; Protein binding potency; Protein binding alerts for skin sensitisation by OASIS v1.3; No structural alerts were found.

Therefore, the C8/C8 component of Fatty acids, C8-10, C8-10 alkyl esters is not expected to have a skin sensitising potential.

Interpretation of results:

other: not predicted to have skin sensitising potential

Reference 5

Endpoint:

skin sensitisation: in vivo (non-LLNA)

Type of information:

experimental study

Adequacy of study:

weight of evidence

Study period:

24 Jul - 16 Aug 1990

Reliability:

2 (reliable with restrictions)

Rationale for reliability incl. deficiencies:

guideline study with acceptable restrictions

Qualifier:

according to guideline

Guideline:

OECD Guideline 406 (Skin Sensitisation)

Deviations:

yes

Remarks:

no data given on reliability check

GLP compliance:

yes

Type of study:

guinea pig maximisation test

Justification for non-LLNA method:

A non-LLNA test is available that was performed prior to the current data requirements, stipulated in Regulation (EC) No 1907/2006. In accordance with the same Regulation, the data was included to avoid unnecessary testing.

Species:

guinea pig

Strain:

other: Pirbright white

Sex:

female

Details on test animals and environmental conditions:

TEST ANIMALS
- Source: Winkelmann Versuchstierzucht, Borchen, Germany
- Age at study initiation: approx. 5 weeks
- Diet: Altromin Haltungsdiät 3032 DK, Lage, Germany, ad libitum; with additive carrots
- Water: tap water with an additive of ascorbic acid (1 g/L), ad libitum
- Mean weight at study initiation: 415 g
- Housing: 2-3 animals in Makrolon type IV cages
- Acclimation period: 5 days
- date of delivery: July 19th, 1990

ENVIRONMENTAL CONDITIONS
- Temperature (°C): 20-25
- Humidity (%): 45-70
- Photoperiod (hrs dark / hrs light): 12 / 12

Route:

intradermal

Vehicle:

paraffin oil

Concentration / amount:

0.5%

Route:

epicutaneous, occlusive

Vehicle:

paraffin oil

Concentration / amount:

40%

No.:

#1

Route:

epicutaneous, occlusive

Vehicle:

paraffin oil

Concentration / amount:

20%

No. of animals per dose:

Preliminary study: 2 animals

Main study:
Test group: 20 females
Control group: 10 females

Details on study design:

RANGE FINDING TESTS: Yes, evaluation of dermal effects was done by treating the animals with 0.5%, 1% or 2% for intracutaneous induction (injection of 0.1 mL into the shaved flank) and 40%, 50%, 60% or 70% for epicutaneous induction and retreatment of the test substance (0.08 g on the shaved flank) and observation of irritating effects 24 h and 48 h after treatment.
Intradermal: Minimal irritation at 0.5% of the test article
Dermal: Minimal irritation at 40%
Based on the results of the preliminary study the minimal irritating concentrations, 0.5% dilution of the test substance in paraffine oil was used for intradermal induction and 40% of the test substance was used for the epidermal induction exposure. A 20% test substance concentration was selected as maximally non-irritating for the challenge phase.

MAIN STUDY
A. INDUCTION EXPOSURE
- No. of exposures: 2 (intradermal and epicutaneous, respectively)
- Exposure period: single application (intradermal induction on Day 1) and 48 hours (epidermal induction on Day 7)
- Test groups: 1
Intradermal (double injections):
Injection 1: 0.1 mL 1:1 mixture (v/v) Freuds'complete adjuvant (FCA) in paraffin oil
Injection 2: 0.1 mL test substance with vehicle (paraffin oil) in concentration minimally irritating (5%)
Injection 3: 0.1 mL test substance in a 1:1 mixture (v/v) with FCA (final concentrations: test substance minimally irritating (5%), FCA 50%)
Epicutaneous: test substance (40%) with vehicle (paraffin oil)

- Control group: 1
Intradermal (double injections; the injections 1 and 3 were identical):
Injection 1 and 3: a 1:1 mixture (v/v) FCA in paraffin oil
Injection 2: only vehicle (paraffin oil)
Epicutaneous: vehicle (paraffin oil)

- Site: symmetrically on both sides of the spine and from cranial to cauda
- Frequency of applications: once
- Concentrations: intradermal: 0.5%, epicutaneous: 40%
- Other: An examination of the injections was performed 1 and 24 hours after treatment.

B. CHALLENGE EXPOSURE
- No. of exposures: 1
- Day(s) of challenge: Day 22 (14 days after induction)
- Exposure period: 24 h
- Test groups: test substance and vehicle (paraffin oil)
- Control group: test substance and vehicle (paraffin oil)
- Site: One sheared flank
- Concentrations: 20% solution in paraffin oil
- Evaluation (hrs after the end of the challenge exposure): 24 and 48 h
- Other: 24 hrs after challenge application the application area was washed off with warm water

Positive control substance(s):

no

Key result

Reading:

1st reading

Hours after challenge:

24

Group:

test chemical

Dose level:

20%

No. with + reactions:

1

Total no. in group:

19

Clinical observations:

One animal died after first induction

Reading:

1st reading

Hours after challenge:

24

Group:

negative control

Dose level:

20%

No. with + reactions:

5

Total no. in group:

10

Clinical observations:

No

Key result

Reading:

2nd reading

Hours after challenge:

48

Group:

test chemical

Dose level:

20%

No. with + reactions:

0

Total no. in group:

19

Clinical observations:

One animal died after first induction

Reading:

2nd reading

Hours after challenge:

48

Group:

negative control

Dose level:

20%

No. with + reactions:

1

Total no. in group:

10

Clinical observations:

No

Group:

positive control

Remarks on result:

not measured/tested

Main study:

Intracutaneous induction: After one hour, weak effects were observed in 7 of 20 treated animals and none of the control animals. 24 h after treatment, 11 of 20 treated animals showed weak effekts and again none of the control animals.

Epicutaneous induction: After one hour, weak up to moderate skin reactions were observed in 16 of 19 treated animals (one died after exposure) and in 7 of 10 control animals. 24 h later mostly weak effects were observed in 10 treated animals and in 2 of the control animals.

Challenge readings - grades of skin reaction of individual animals

 

Animal No.	Intracut. induction		Epicut. induction		Challenge
	1 h	24 h	1 h	24 h	24 h	48 h
Control Animals
27	0	0	1	0	1	0
28	0	0	1	0	1	0
29	0	0	1	0	0	0
30	0	0	1	0	0	0
31	0	0	0	0	1	0
32	0	0	2	1	0	0
33	0	0	1	1	1	0
34	0	0	0	0	1	1
35	0	0	0	0	0	0
36	0	0	1	0	0	0
Test Animals
1	0	0	2	1	0	0
2	1	0	2	0	0	0
3	0	1	1	0	0	0
4	1	1	1	1	0	0
5	1	1	1	0	0	0
6	0	1	1	0	0	0
7	1	1	0	0	0	0
8	0	0	1	1	0	0
9	1	1	-	-	-	-
10	0	0	1	0	0	0
11	0	0	0	0	0	0
12	0	1	2	1	0	0
13	0	0	0	0	0	0
14	0	0	0	0	0	0
15	1	0	0	0	0	0
16	0	1	2	2	1	0
17	0	0	1	1	0	0
18	0	1	2	2	0	0
19	0	1	0	0	0	0
20	1	0	1	1	0	0

One animal died after first exposure. No significant differences in the gain of body weight was observed between treatment and control group.

Interpretation of results:

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

Conclusions:

CLP: not classified

Reference 6

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:

adopted 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)

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:

other: disintegrations per minute (DPM)

Remarks on result:

other: 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.

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%

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

Conclusions:

CLP: not classified

Endpoint conclusion

Endpoint conclusion:

no adverse effect observed (not sensitising)

Additional information:

Justification for read-across

There are no available data on the skin sensitisation potential of Fatty acids C8-10, C8-10 alkyl esters (CAS 129677-93-6). The assessment was therefore based on QSAR modelling and studies conducted 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) and within Chapter 5.1 of the CSR.

Skin sensitisation

 

CAS 129677-93-6

The composition of the target substance Fatty acids C8-10, C8-10 alkyl esters includes the alkyl esters Octyl octanoate, Octyl decanoate, Decanoyl octanoate and Decanoyl decanoate. In order to make a thorough assessment on the skin sensitisation potential of Fatty acids C8-10, C8-10 alkyl esters, the 4 above-mentioned alkyl esters representing the main components of the target substance were run in the OECD QSAR Toolbox v3.3 (WoE, 2015, QSAR of 4 main components). Moreover, there was no alert for protein binding specifically related to skin sensitisation potential in the OASIS v1.3 database.

  

CAS 135800-37-2

A Guinea pig maximisation test was performed with Fatty acids, C8-16, 2-ethylhexyl esters (CAS 135800-37-2) according to OECD Guideline 406 (WoE, 1991). 19 treatment and 10 control animals (Dunkin-Hartley guinea pigs) were induced intradermally with 5% test substance (100% pure) diluted in peanut oil on both sides of the spine with and without Freud's complete adjuvant. 7 days later a 40% test substance dilution was used for the epidermal induction for 48 hours. Another 14 days later the animals were challenged by epidermal induction of the sheared flank skin with test substance diluted to 20% with paraffin oil. 24 and 48 hours after termination of challenge exposure skin readings revealed no indications for a skin sensitising potential of the test substance.

 

CAS 3687-46-5

The skin sensitising potential of Decyl oleate (CAS 3687-46-5) was evaluated in a local lymph node assay (LLNA) performed according to OECD 429 (WoE, 2010). 25 µl of a 25, 50 and 100% suspension of test substance in acetone/olive oil (4:1 v/v) was applied to the dorsal surface of both ears of 5 CBA mice/dose for 3 consecutive days. On Day 6, each animal was injected via the tail vein with 0.25 mL sterile phosphate buffered saline containing 20 µCi of 3H-methyl thymidine. After approximately 5 hours, the mice were sacrificed and the draining lymph nodes of the ears were excised. The nodes were pooled for each animal in PBS and the DNA precipitated with 5% TCA at 4 °C overnight. Slight edema (score 1 of 4) was noted on the ears of 5/5 mice treated with the undiluted substance. This is not considered to have had a significant effect on the activity of the lymph nodes. All the nodes of the animals in the control and treatment groups were normal in size, and no macroscopic abnormalities were noted in the surrounding area. The positive control group (hexyl cinnamic aldehyde) was valid. The mean DPM/animal values for the control, 25, 50 and 100% groups were 488, 571, 951 and 1013, respectively. The SI values calculated for the 25, 50 and 100% groups were 1.2, 2.0 and 2.1, respectively. The SI was lower than 3 up to and including 100%, therefore the test substance is considered to be not skin sensitising. 

CAS 2306-88-9

A human patch test evaluating the skin sensitising potential of Octyl octanoate is available. 111 volunteers (83 females, 28 males) in the age range of 18 to 79 years were included in the study (WoE, 2008). During the induction phases, patches with 0.2 mL of 12.5% test material (100% pure) in corn oil were applied under semi-occlusive conditions three times a week to the back for 24 hours. A total of nine applications were performed and the skin effects were scored 24 or 48 hours after patch removal. Approximately two weeks after the final induction patch removal, a challenge patch was applied under semi-occlusive conditions for 24 hours. The site was scored for edema and skin effects 24 and 72 hours after application. 105 volunteers completed the study and none of them showed any skin reaction.

Conclusion

A weight-of-evidence approach was applied to assess the skin sensitising potential of the test substance Fatty acids C8-10, C8-10 alkyl esters (target substance). The main components of the target substance were run in the OECD QSAR Toolbox v3.3. No structural alerts were given for general protein binding in the OECD QSAR toolbox databases, nor was there an alert for protein binding specifically related to skin sensitisation potential in the OASIS database. This indicates that none of the individual components are likely to cause skin sensitisation. A LLNA study performed with the source substance Decyl oleate (CAS 3687-46-5) was negative, while for the source substance Fatty acids, C8-16, 2-ethylhexyl esters (CAS 135800-37-2), the result of a GMPT study was negative. The result of a human patch test for the source substance Octyl octanoate (CAS 2306-88-9) was likewise negative for skin sensitisation. Taking into account all the available information, the test substance is considered to be not 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 Fatty acids C8-10, C8-10 alkyl esters (CAS 129677-93-6), data will be generated from data for reference source substance(s) and QSAR predictions 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 combined with QSAR analyses performed with the main components, 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.