Isobutyl laurate

Endpoint summary

Key value for chemical safety assessment

Skin sensitisation

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 sensitisation of isobutyl laurate (CAS 37811-72-6). 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	Chemical name	Molecular weight [g/mol]	Skin sensitisation
37811-72-6 (a)	Isobutyl laurate	256.42	WoE: RA: CAS 110-27-0 RA: CAS 163961-32-8
110-27-0 (b)	Isopropyl myristate	270.45	Experimental result: not sensitising
163961-32-8 (b)	Fatty acids, C16-18 and C18 unsatd. branched and linear, butyl esters	312.53-340.58	Experimental result: not sensitising

(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 isobutyl laurate (CAS 37811-72-6). A detailed analogue approach justification is provided in the technical dossier (see IUCLID Section 13).

 

Discussion

No data on skin sensitisation is available with isobutyl laurate (CAS 37811-72-6). Therefore, read across from the structurally analogue substances isopropyl myristate (CAS 110-27-0) and Fatty acids, C16-18 and C18 unsatd. branched and linear, butyl esters (CAS 163961-32-8) was applied.

Skin sensitisation

CAS 110-27-0

The skin sensitising properties of isopropyl myristate (CAS 110-27-0) were tested in a study equivalent or similar to OECD TG 406 using the Guinea pig maximization test (GPMT, Potokar, 1984). The GPMT test was performed on 15 female Pirbright-Hartley guinea pigs. For the intradermal and epicutaneous inductions the initial test item concentration was 5% (v/w; in 2% carboxymethylcellulose and 0.5% cremophor (intradermal); in 5% vaseline (epicutaneous)) whereas a 25% (v/w in 2% carboxymethylcellulose and 0.5% cremophor) formulation of the test item was selected for the challenge exposure. At the beginning of the induction exposure 15 test animals and 19 control animals were either intradermally treated with 5% of the test substance or vehicle (Day 0), followed by a topical induction (5% or vehicle) under occlusive conditions one week later. On Day 22 all animals were challenged with the test substance at a concentration of 25%. Skin reactions of all animals were evaluated 48 and 72 hours after challenge administration. Challenge exposure with the test item revealed no skin reactions in any of the 15 animals. Furthermore no skin reactions were observed in the negative controls (19 animals). Although no information on periodic reliability checks with a positive control is available the test with this typically used animal test strain is deemed reliable. Thus, under the conditions of the test, the test substance revealed no skin sensitizing properties.

 

CAS 163961-32-8

The skin sensitising properties of fatty acids, C16-18 and C18 unsatd. branched and linear, butyl esters (CAS 163961-32-8) were tested in a study according to OECD TG 406 under GLP conditions using the Guinea pig maximization test (GPMT, Sanders, 2002c). The GPMT test was performed on 10 male Dunkin-Hartley guinea pigs. For the intradermal and epicutaneous inductions the initial test item concentration was 1% (v/v in arachis oil) and 100%, respectively, whereas a 50% and 75 % (v/v in arachis oil) formulation of the test item was selected for the challenge exposure. At the beginning of the induction exposure 10 test animals and 5 control animals were either intradermally treated with 1% of the test substance or vehicle (Day 0), followed by a topical induction (100% or vehicle) under occlusive conditions one week later. On Day 22 all animals were challenged with the test substance at a concentration of 50% and 75%. Skin reactions of all animals were evaluated 24 and 48 hours after challenge exposure (after removal of the patch). A transient challenge reaction (slight erythema, grade 1) was observed in 1/10 animals of the test group at the 24 h reading time point (75% test substance), only, with desquamation evident at the 48 h reading time point. Furthermore no skin reactions were observed in the negative controls (5 animals). Periodic reliability checks had been performed 2 times a year with 10 test and 5 control animals using alpha-hexylcinnamaldehyde and 2-mercaptobenzothiazole as positive control substances confirming the sensititvity of the used animal strain. Thus, under the conditions of the test, the test substance revealed no skin sensitising properties.

Taken together, the available data on skin sensitisation from structural analogue substances do not indicate any sensitising potential.Therefore, according to EU classification criteria, the target substance isobutyl laurate (CAS 37811-72-6) is not to be classified.

Migrated from Short description of key information:
Skin sensitisation (OECD 406), guinea pig: not sensitising (RA CAS 110-27-0 and RA CAS 163961-32-8)

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.

References:

A detailed reference list is provided in the technical dossier (see IUCLID, section 13) and within the CSR.

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 isobutyl laurate (CAS 37811-72-6), data will be generated from data for reference source substance(s) to avoid unnecessary animal testing. Additionally, once the analogue read-across concept is applied, substances will be classified and labelled on this basis.

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.