Hexadecyl (R)-12-hydroxyoleate

Endpoint summary

Key value for chemical safety assessment

Skin sensitisation

Endpoint conclusion

Endpoint conclusion:

no adverse effect observed (not sensitising)

Additional information:

Justification for read-across

There are no in vivo data on the skin sensitisation potential of Hexadecyl (R)-12-hydroxyoleate (CAS 10401-55-5). The assessment was therefore based on QSAR modelling and a study conducted with an analogue (source) substance 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).

Skin sensitisation

QSAR predictions

 

CAS 10401-55-5

The potential for Hexadecyl (R)-12-hydroxyoleate to bind to proteins, which is known to be an indicator of potential skin sensitisers, was predicted in the QSAR OECD Toolbox (Nordheim, 2015). No structural alerts were given for a skin sensitisation potential in the Danish EPA database. There was no alert for protein binding specifically related to skin sensitisation potential.

Animal studies

CAS 17673-56-2

The skin sensitising potential of (Z)-octadec-9-enyl (Z)-docos-13-enoate (CAS 17673-56-2) was evaluated in a Buehler test performed according to a protocol similar to OECD 406 and under GLP conditions (Pitterman, 1995). The induction treatments were performed on 20 Dunkin Hartley guinea pigs on Day 0, 7 and 14. A 70% solution of the test substance in peanut oil was applied to the shaved skin on the flank of the animals, and covered with an occlusive dressing for 6 hours. On Day 28, all the animals were challenged with a 60% solution of the test substance via topical application on the flank for 6 hours, using an occlusive dressing. 10 guinea pigs in the control group were treated according to the same protocol with the vehicle as the control substance. During the first reading, 1/20 treated animals and 1/10 negative control animals had a positive reaction, respectively. In the second reading, 2/20 treated animals and 1/10 negative control animals had a positive reaction, respectively. The slight, patchy erythema was limited to the left flank, where both the induction and challenge doses were applied. It is possible that the reaction was skin irritation, rather than a sensitisation reaction. All skin irritation effects had cleared within 72 hours after the challenge exposure ended. The result of the reliability check was inconclusive. During the first challenge application with 25% alpha-hexyl cinnamic aldehyde, a sensitisation reaction was induced in 25% (5/20) of the Dunkin Hartley guinea pigs, while the second challenge application did not cause sensitisation reactions. In the negative control group, the first challenge application induced sensitisation in 20% (2/10) of the animals, and the second challenge application did not cause sensitisation reactions. The results of the study are still considered to be valid as the first results could not be reproduced. Under the conditions of this study, the test substance is considered to be not skin sensitising.

Overall conclusion

The OECD QSAR Toolbox (Danish EPA database) did not predict a skin sensitising potential for the target substance. A GPMT study performed with a source substance was negative. Taking into account the available information, Hexadecyl (R)-12-hydroxyoleate is not expected to be skin sensitising.

Migrated from Short description of key information:
Skin sensitisation (GPMT, QSAR): not sensitising

Justification for selection of skin sensitisation endpoint:
Hazard assessment is conducted by means of read-across from a structural analogue. The selected study is the most adequate and reliable study based on the identified similarities in structure and intrinsic properties between the 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

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 (R)-12-hydroxyoleate (CAS 10401-55-5), 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 QSAR prediction made with the target substance and 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.