Octadecanoic acid, C16-20-branched alkyl esters

Endpoint summary

Description of key information

Skin, rabbit (OECD 404): not irritating

Eye, rabbit (OECD 405): not irritating

Key value for chemical safety assessment

Skin irritation / corrosion

Endpoint conclusion

Endpoint conclusion:

no adverse effect observed (not irritating)

Eye irritation

Endpoint conclusion

Endpoint conclusion:

no adverse effect observed (not irritating)

Respiratory irritation

Endpoint conclusion

Endpoint conclusion:

no study available

Additional information

Analogue justification

There are no available data on the skin and eye irritation effects of octadecanoic acid, C16-20-branched alkyl esters (CAS 85203-92-5). The assessment was therefore based on studies conducted with analogue 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).

 

Skin irritation

CAS 72576-80-8

A skin irritation study was performed with hexadecanoic acid isooctadecyl ester (CAS 72576-80-8), according to OECD guideline 404 and under GLP conditions (key study, 1999). 0.5 mL of the test substance was applied to the shaved skin of 3 New Zealand White rabbits and held in place by a semi-occlusive dressing for 4 hours. The severity of erythema and edema was scored 1, 24, 48 and 72 hours after patch removal. No skin irritation was observed at any time point in any animal; all erythema and edema scores were 0. The test substance is not considered to be irritating to the skin.

 

CAS 3234-85-3

A skin irritation study was performed with tetradecanoic acid, tetradecyl ester (CAS 3234-85-3), using a protocol similar to OECD guideline 404 (supporting study, 1985). The test substance was applied to the shaved or abraded skin of 6 male rabbits and held under occlusive conditions for 24 hours. The reading time points were 24- and 72 hours after patch removal. 1/6 animals had slight erythema (score 1 of 4) on the intact skin at the 24-hour reading time point, which had cleared completely by the 72-hour reading time point. No other skin irritation effects were observed in any animals (6/6). The results of the abraded skin sites were comparable, but not taken into account for hazard assessment. To be able to calculate the mean scores, the 48-hour scores were assumed to be the same as those determined 24 h after patch removal (worst case assumption). The mean erythema scores (over 24, 48 and 72 hours) were 0, 0.67, 0, 0, 0, and 0 while the mean edema scores (over 24, 48 and 72 hours) were all 0. The test substance is not considered to be irritating to the skin.

 

CAS 95912-86-0

A skin irritation study was performed with fatty acids, C8-10, C12-18 alkyl esters (CAS 95912-86-0), according to a protocol similar to OECD guideline 404 (supporting study, 1991). 0.5 mL of the test substance was applied to the shaved skin of 3 male rabbits and held in place by an occlusive dressing for 4 hours. The reading time points were 1, 24, 48 and 72 hours after patch removal. 1 hour after exposure, all the animals had slight to well-defined erythema (score 1 – 2), while 2/3 had very slight to slight edema (score 1 – 2). These effects gradually reduced in severity. 24 hours after exposure ended, 1/3 animals had very slight erythema and slight edema. The edema persisted until the 48-hour reading time point. All skin irritation effects had cleared completely within 72 hours after the exposure ended. The mean erythema scores (over 24, 48 and 72 hours) were 0.33, 0 and 0 while the mean edema scores (over 24, 48 and 72 hours) were 1, 0 and 0. The test substance is not considered to be irritating to the skin.

 

CAS 93803-87-3

The skin irritation potential of 2-octyldodecyl isooctadecanoate (CAS 93803-87-3) was assessed in a study performed according to OECD 404 and under GLP conditions (supporting study, 1998). 0.5 g test substance was applied to the shaved skin of rabbits under semi-occlusive conditions for 4 hours. The skin irritation effects were scored 1, 24, 48 and 72 h after patch removal. 3/3 animals had well-defined erythema (score 2) at the 1-hr reading time point. The erythema had reduced in severity by 24 hours after exposure in 3/3 rabbits (score 1, 1, 1), and had cleared completely within 72 hours for 3/3 rabbits. The mean erythema scores (over 24, 48 and 72 hours) were 0.67, 0.33 and 0.33. No edema was observed in any animal at any time point. The test substance is not considered to be irritating to the skin.

 

 

Eye irritation

CAS 72576-80-8

The eye irritation potential of hexadecanoic acid, isooctadecyl ester (CAS 72576-80-8) was evaluated in a study performed according to OECD 405 and in compliance with GLP (key study, 1999). 0.1 mL test substance was instilled into one eye of 3 male rabbits, and the eyes remained unwashed. The eye irritation effects were scored according to the Draize scoring system 1, 24, 48, and 72 hours, and 7 days after application. At the 1-hour reading time point, 3/3 rabbits had slight-moderate conjunctivae (scores 1, 1,2), and 2/3 had slight chemosis (score 1). The chemosis had cleared by the 24-hour reading time point; while 3/3 animals still had slight conjunctivae (score 1). All eye irritation effects were fully reversible within 48 hours. No cornea opacity or iris changes were observed in any rabbit at any time point. The mean conjunctivae score (over 24, 48 and 72 hours) was 0.33, 0.33 and 0.33, while the mean chemosis score (over 24, 48 and 72 hours) was 0, 0 and 0. The mean cornea score and iris score (over 24, 48 and 72 hours) was 0 for all animals. Based on the results of the study, the test substance is not considered to be irritating to the eyes.

CAS 3234-85-3

An eye irritation study was performed with tetradecanoic acid, tetradecyl ester (CAS 3234-85-3) according to a protocol similar to OECD 405, and summarised in a short report (supporting study, 1976). 0.1 mL of a 50% solution of the test substance in corn oil was instilled into the eye of 6 rabbits. The eyes were not washed after the treatment. The eye irritation effects were scored according to the Draize scoring system 24, 48, and 72 hours after application. Slight conjunctivae (score 1) was observed in 4/6 animals at the 24-hour reading time point, which persisted in 1/6 rabbits until the 48-hour reading time point. The conjunctivae had cleared completely within 72 hours. No chemosis and no changes in cornea opacity or the iris were observed in any rabbit at any time point. The mean conjunctivae score (over 24, 48 and 72 hours) was 0.67, 0.33, 0, 0.33, 0.33 and 0. As a dilution was used, the results cannot be used for classification purposes.

 

CAS 93803-87-3

The eye irritation potential of 2-octyldodecyl isooctadecanoate (CAS 93803-87-3) was evaluated in a study performed according to OECD 405 and in compliance with GLP (supporting study, 1998). 0.1 mL test substance was instilled into one eye of rabbits, and the eyes remained unwashed. The eye irritation effects were scored according to the Draize scoring system 1, 24, 48, and 72 hours, and 7 days after application. Remains of the test substance were noted in the treated eye of 3/3 animals on Day 1, while remains were present on the outside of the eyelids on Day 2 in 1/3 animals. At the 1-hour reading time point, 3/3 rabbits had slight conjunctivae (score 1), which was still present in 1/3 rabbits at the 24-hour reading time point. The effect had cleared completely within 48 hours. No chemosis and no cornea opacity or iris changes were observed in any rabbit at any time point. The mean conjunctivae score (over 24, 48 and 72 hours) was 0.33, 0 and 0. Based on the results of the study, the test substance is not considered to be irritating to the eyes.

 

Overall conclusion for skin and eye irritation

The available data on suitable source substances did not show any skin or eye irritation effects. Therefore, the target substance octadecanoic acid, C16-20-branched alkyl esters is not expected to be a skin irritant or an eye irritant.

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 octadecanoic acid, C16-20-branched alkyl esters, 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.

 

The available data on skin and eye irritation do not meet the classification criteria according to Regulation (EC) 1272/2008 and are therefore conclusive but not sufficient for classification.