Fatty acids, C18-unsatd., trimers, 2-ethylhexyl esters

Endpoint summary

Key value for chemical safety assessment

Skin sensitisation

Link to relevant study records

Reference

Endpoint:

skin sensitisation: in vivo (LLNA)

Type of information:

migrated information: read-across from supporting substance (structural analogue or surrogate)

Adequacy of study:

key study

Study period:

14 Apr - 16 May 2010

Reliability:

2 (reliable with restrictions)

Rationale for reliability incl. deficiencies:

other: see 'Remark'

Remarks:

GLP - Guideline study. According to the ECHA guidance document "Practical guide 6: How to report read-across and categories (March 2010)", the reliability was changed from RL1 to RL2 to reflect the fact that this study was conducted on a read-across substance.

Qualifier:

according to guideline

Guideline:

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

Version / remarks:

adopted in 2002

Deviations:

no

GLP compliance:

yes

Type of study:

mouse local lymph node assay (LLNA)

Species:

mouse

Strain:

CBA

Sex:

male/female

Details on test animals and environmental conditions:

TEST ANIMALS
- Source: Harlan, Horst, The Netherlands
- Age at study initiation: 10 weeks
- Mean weight at study initiation: 20.9 g
- Housing: Individual housing in labelled Makrolon cages (MI type; height 12.5 cm) containing sterilized sawdust as bedding material (Litalabo, S.P.P.S., Argenteuil, France). Paper (Enviro-dri, Wm. Lillico & Son (Wonham Mill Ltd), Surrey, United Kingdom) was supplied as cage-enrichment.
The paper was removed on Day 1 prior to dosing and was supplied again after scoring of the ears on Day 3.
- 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 before the start of treatment under laboratory conditions, accommodation was as described above except that the animals were group housed in Makrolon cages (MIII type; height 18 cm)

ENVIRONMENTAL CONDITIONS
- Temperature (°C): 21.0 ± 3.0 (actual range: 19.7 – 22.9)
- Humidity (%): 40-70 (actual range: 37 - 83)
- Air changes (per hr): 15
- Photoperiod (hrs dark / hrs light): 12/12

Vehicle:

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

Concentration:

0, 25, 50 and 100% (w/w)

No. of animals per dose:

5

Details on study design:

RANGE FINDING TESTS:
A preliminary irritation study was conducted in order to select the highest test substance concentration to be used in the main study. In principle, this concentration should be well tolerated systemically by the animals and may give moderate irritation at the highest concentration. Based on the results, the highest test substance concentration selected for the main study was a 100% concentration.

MAIN STUDY
ANIMAL ASSIGNMENT AND TREATMENT
- Name of test method: Local Lymph Node Assay
- Criteria used to consider a positive response: Disintegrations Per Minute (DPM) values are presented for each animal and for each dose group. A Stimulation Index (SI) is 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 sensitizer, based on the test guideline and recommendations done by ICCVAM. The results were evaluated according to the Globally Harmonized System of Classification and Labelling of Chemicals (GHS) of the United Nations (2007) and the Regulation (EC) No 1272/2008 of the European Parliament and of the Council of 16 December 2008 on classification, labelling and packaging of substances and mixtures.


TREATMENT PREPARATION AND ADMINISTRATION: The dorsal surface of both ears was epidermally treated (25 μL/ear) with the test substance concentration, at approximately the same time per day. Each animal was injected via the tail vein with 0.25 mL of sterile phosphate buffered saline (PBS) (Merck, Darmstadt, Germany) containing 20 μCi of 3H-methyl thymidine (PerkinElmer Life and Analytical Sciences, Boston, MA, US). After approximately five hours, all animals were killed by intraperitoneal injection with Euthasol® 20% (AST Farma BV, Oudewater, The Netherlands). The draining (auricular) lymph node of each ear 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 and radioactive measurements were performed using a Packard scintillation counter (2800TR).

Positive control substance(s):

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

Positive control results:

The six-month reliability check with alpha-hexylcinnamic aldehyde indicated that the Local Lymph Node Assay as performed at NOTOX is an appropriate model for testing for contact hypersensitivity.

Parameter:

SI

Remarks on result:

other: The SI values calculated for the substance concentrations 25, 50 and 100% were 1.6, 1.6 and 2.5, respectively.

Parameter:

other: disintegrations per minute (DPM)

Remarks on result:

other: Mean DPM/animal values for the experimental groups treated with test substance concentrations 25, 50 and 100% were 1644, 1717 and 2675 DPM respectively. The mean DPM/animal value for the vehicle control group was 1060 DPM.

Table 1: Radioactivity measurements (individual animals)

group	test substance^1(% w/w)		animal	DPM / animal
1	0%	1		1529
	(Vehicle)	2		578
		3		1355
		4		939
		5		898
2	25%	6		678
		7		2490
		8		2104
		9		1235
		10		1712
3	50%	11		1506
		12		1544
		13		2260
		14		1497
		15		1780
4	100%	16		3393
		17		2354
		18		2537
		19		2339
		20		2751

¹      Vehicle: Acetone/Olive oil (4:1 v/v).

Interpretation of results:

not sensitising

Remarks:

Migrated information Criteria used for interpretation of results: EU

Conclusions:

CLP: not classified
DSD: not classified

Endpoint conclusion

Endpoint conclusion:

no adverse effect observed (not sensitising)

Additional information:

Justification for grouping of substances and read-across

There are no data available for the skin sensitisation of Fatty acids, C18 unsatd., trimers, 2-ethylhexyl esters (CAS 173832-46-7). In order to fulfil the standard information requirements set out in Annex VII, 8.3, in accordance with Annex XI, 1.5, of Regulation (EC) No 1907/2006, read-across from structurally related substances was conducted.

In accordance with Article 13 (1) of Regulation (EC) No 1907/2006, "information on intrinsic properties of substances may be generated by means other than tests, provided that the conditions set out in Annex XI are met.” In particular for human toxicity, information shall be generated whenever possible by means other than vertebrate animal tests, which includes the use of information from structurally related substances (grouping or read-across).

Having regard to the general rules for grouping of substances and read-across approach laid down in Annex XI, Item 1.5, of Regulation (EC) No 1907/2006 whereby substances may be predicted as similar provided that their physicochemical, toxicological and ecotoxicological properties are likely to be similar or follow a regular pattern as a result of structural similarity.

Overview of skin sensitisation

CAS	173832-46-7 (a)	68334-05-4 (b)
Chemical Name	Fatty acids, C18 unsatd., trimers, 2-ethylhexyl esters	Fatty acids, C18-unsatd., dimers, 2-ethylhexyl esters (ESIS: NLP)
Molecular weight	973.62 1085.84 1184.02	673.10
Skin sensitisation	RA: CAS 68334-05-4	Experimental result: not sensitising

(a) Category members subjected to the REACh  Phase-in registration deadline of 31 May 2013 are indicated in bold font.

(b) Surrogate substances are indicated in normal font and are precursors/breakdown products of the target substance (i.e. alcohol and fatty acid moieties). Available data on these substances are used for assessment of toxicological properties by read-across on the same basis of structural similarity and/or mechanistic reasoning as described for the present analogue approach.

The above mentioned substances are considered to be similar on the basis of the structural similar properties and/or activities. The available endpoint information is used to predict the same endpoints Fatty acids, C18 unsatd., trimers, 2-ethylhexyl esters (CAS 173832-46-7).

A detailed analogue approach justification is provided in the technical dossier (see IUCLID Section 13).

 

Discussion

Skin sensitisation

CAS 68334-05-4

The skin sensitising potential of Fatty acids, C18-unsatd., dimers, 2-ethylhexyl esters was investigated in a modified Local Lymph Node Assay (LLNA) in CBA mice according to OECD guideline 429 and in compliance with GLP (Stitzinger, 2010). Based on a preliminary range finding test, 5 animals per sex and group were exposed to test substance at concentrations of 25, 50 and 100% (w/w) in acetone/olive oil (4:1 v/v) or vehicle alone, respectively. The dorsal surface of both ears was epidermally treated with the test substance (25 μL/ear) at the respective concentrations for three consecutive days. On Day 3 (3-4 hours after treatment), the skin was examined for erythema and edema and the grade of reaction was scored. On Day 6, each animal was injected via the tail vein with 0.25 mL of sterile phosphate buffered saline containing 20 μCi of 3H-methyl thymidine. After approximately 5 h, all animals were sacrificed and the draining (auricular) lymph node of each ear was excised. Single cell suspensions of pooled lymph nodes from each individual animal were prepared and cell proliferation was measured by incorporation of ³H-methyl thymidine and expressed as the amount of radioactive disintegration per minute (DPM). The mean DPM/lymph node for each test group was 1644, 1717 and 2675 at concentrations of 25, 50 and 100% of the test substance, respectively. The mean DPM/animal value for the vehicle control group was 1060. Based on these results, SI values of 1.6, 1.6 and 2.5 were calculated for test substance at concentrations of 25, 50 and 100%, respectively. The EC3 value could not be calculated as the stimulation indices of all concentrations were below 3. Local effects on the treated skin of ears involved slight erythema in all animals treated with the undiluted test substance. Visual examination of lymph nodes revealed a slight enlargement in animals exposed to 50 and 100% of the test substance. No mortality occurred and no symptoms of systemic toxicity were observed in the animals. The historical positive control alpha hexyl cinnamic aldehyde was tested at regular intervals at concentrations of 5, 10 and 25% in acetone/olive oil (4:1 (v/v) and confirmed the sensitivity and reliability of the experimental technique. Under the above mentioned conditions, the test substance was not found to be a sensitiser in the modified LLNA.

Based on the available data, Fatty acids, C18-unsatd., dimers, 2-ethylhexyl esters is not sensitising.

Conclusion for sensitisation

In summary, no study was available assessing the skin sensitisation potential of Fatty acids, C18-unsatd., trimers, 2-ethylhexyl esters, thus read across to the surrogate substance Fatty acids, C18-unsatd., dimers, 2-ethylhexyl esters was performed, which showed no potential for skin sensitisation.

In conclusion, the available data indicate that no hazard for skin sensitisation for Fatty acids, C18-unsatd., trimers, 2-ethylhexyl esters has to be expected.

Migrated from Short description of key information:
Skin sensitisation (OECD 406): not sensitising (based on read-across from CAS 68334-05-4)

Justification for selection of skin sensitisation endpoint:
Hazard assessment is conducted by means of read-across from a structural surrogate. The selected study is the most adequate and reliable study based on the identified similarities in structure and intrinsic properties between source and target substance and overall quality assessment (refer to the endpoint discussion for further details).

Respiratory sensitisation

Endpoint conclusion

Endpoint conclusion:

no study available

Additional information:

Justification for selection of respiratory sensitisation endpoint:
Study not required according to Annex VII-X of Regulation (EC) No 1907/2006.

Justification for classification or non-classification

Based on read-across from the surrogate substances, 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.