Fatty acids, C18-unsatd, dimers, hydrogenated, diisopropyl 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 - 06 May 2010

Reliability:

2 (reliable with restrictions)

Rationale for reliability incl. deficiencies:

other: see 'Remark'

Remarks:

GLP - Guideline study, tested with the source substance Fatty acids, C18-unsatd., dimers, 2-ethylhexyl esters (CAS 68334-05-4). In accordance to the ECHA guidance document “Practical guide 6: How to report read-across and categories (Dec 2012)”, 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)

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: approx. 10 weeks old
- Weight at study initiation: +/- 20% of the sex mean
- 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: 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

Value:

2.5

Test group / Remarks:

100% group

Parameter:

SI

Value:

1.6

Test group / Remarks:

50% group

Parameter:

SI

Value:

1.6

Test group / Remarks:

25% group

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^x1(% 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

 ^x1Vehicle: 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 only limited data available on skin sensitization of Fatty acids, C18-unsatd., dimers, hydrogenated, diisopropyl esters (CAS 103213-20-3). 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 sensitization:

CAS	Chemical name	Molecular weight	Skin sensitization
103213-20-3 (a)	Fatty acids, C18-unsatd., dimers, hydrogenated, diisopropyl esters	645	RA: CAS 68334-05-4
68334-05-4 (b)	Fatty acids, C18-unsaturated, dimers, 2-ethylhexyl esters	673	Experimental result: not sensitizing

(a) The substance subject to registration is indicated in bold font.

(b) Reference (read-across) substances are indicated in normal font. Lack of data for a given endpoint is indicated by “--“.

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 for Fatty acids, C18-unsatd., dimers, hydrogenated, diisopropyl esters (CAS 103213-20-3). A detailed analogue approach justification is provided in the technical dossier (see IUCLID Section 13).

Discussion

Skin sensitization

Beside a non-reliable skin sensitization study (CIR, 2003; RL4) indicating no sensitization to skin in humans no further data on skin sensitization are available with Fatty acids, C18-unsatd., dimers, hydrogenated, diisopropyl esters (CAS 103213-20-3). Therefore, read across from the structurally analogue Fatty acids, C18-unsaturated, dimers, 2-ethylhexyl esters (CAS 68334-05-4) was applied. The skin sensitizing properties of Fatty acids, C18-unsaturated, dimers, 2-ethylhexyl esters (CAS 68334-05-4) were tested in a study according to OECD TG 429 and in compliance with GLP (Stitzinger, 2010b) using the local lymph node assay (LLNA). In this study groups of five female CBA/J mice were treated with the test item at concentrations of 25, 50 and 100% (w/w) in acetone/olive oil (4:1 v/v). Topical application of 25 µL of the appropriate test substance concentrations was performed daily at the dorsal surface of each ear for three consecutive days. Five days following the first topical application of the test item or vehicle all mice were injected via the tail vain with 250 µL PBS containing ³H-methylthymidine (20 µCi per mouse). Five hours after injection single cell suspension of pooled lymph nodes was prepared for each animal, followed by determination of ³HTdR incorporation. Positive and negative controls were included in the study and gave the expected results. The calculated stimulation indices (SI) of the test substance are 1.6, 1.6 and 2.5 at concentrations of 25, 50 and 100% (w/w), respectively and therefore < 3. Thus, under the conditions of the test, the test substance revealed no skin sensitizing properties.

Migrated from Short description of key information:
Skin sensitization (OECD 429): not sensitizing (RA CAS 68334-05-4)

Justification for selection of skin sensitisation endpoint:
Hazard assessment is conducted by means of read-across from structural analogues. All available studies are adequate and reliable based on the identified similarities in structure and intrinsic properties between source and target substances and overall quality assessment.

Respiratory sensitisation

Endpoint conclusion

Endpoint conclusion:

no study available

Justification for classification or non-classification

The available data on skin sensitization of Fatty acids, C18-unsatd., dimers, hydrogenated, diisopropyl esters do not meet the criteria for classification according to Regulation (EC) 1272/2008 and are therefore conclusive but not sufficient for classification.