Registration Dossier

Administrative data

Description of key information

In vitro Skin Irritation (EU Method B.46: RHE Model Test): not irritating 
RA-S CAS 112-84-8, OECD 404, rabbit, 4h semiocclusive: not irritating
In vitro Eye Irritation (Reconstructed Human Corneal Epithelium Model): not irritating
In vivo Eye Irritation, 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

There is an in vitro skin irritation study available for Amides, C16-C18 (even numbered) (Warren, 2010) conducted according to EU Method B.46. This is a validated method that has been accepted by the authorities in the light of animal welfare for the assessment of skin irritating potential. Therefore, it was chosen as key study. The study was performed with the EPISKIN Reconstituted Human Epidermis Model. The human epidermal cultures were topically treated with the test substance for 15 minutes, followed by a 42-hour post-exposure incubation period. Thereafter cell viability in the culture was assessed by means of the colourimetric MTT reduction assay. In this experimental setting the test substance had no adverse effects on cell viability in the human epidermal culture. Therefore, the substance was considered to be non-irritating to the skin in vitro under the conditions of the test.

As additional support for the in vitro data, although not necessary from a regulatory standpoint, read-across data from an in vivo skin irritation test according to OECD Guideline 404, performed in 3 animals with erucamide (CAS 112-84-5), a structurally related substance, is included and chosen as additional key study (Daamen, 1988).

Erucamide is the fatty acid amide resulting from the amidation of erucic acid. Erucic acid is a mono-unsaturated fatty acid with a carbon chain consisting of 22 carbon atoms with a double bond at position 13 (omega-9) of the carbon chain (cis-docos-13-enoic acid). Comparable to stearamide, the main constituent of Amides C16-C18 (even numbered), it is not classified in Annex I of Directive 67/548/EEC, and does not have to be self-classified according to the available experimental data. Erucic acid is also present in various oils and fats which are part of our diets (20-40% in oils from mustard seeds and up to 50% in original high erucic rapeseed oil, <2% in low erucic acid rapeseed oil; Beare-Rogers, 2001) and will also be broken down into shorter-chain fatty acids in the process of beta-oxidation. One of the most famoust uses is in Lorenzo's oil, a 4:1 mixture of the triglyceride forms of oleic and erucic acid, i.e. an investigational drug used for the treatment of adrenoleukodystrophy, for which an U.S. Patent was established.

In this skin irritation study the animals were exposed for 4 hours under semiocclusive conditions. Only slight erythema 1 hour after removal of the dressing was observed, which was completely reversible within 24 hours, and no signs of systemic toxicity were observed. Based on these results the structurally related substance was considered as not irritating. Therefore, Amides, C16-C18 (even numbered) does not have to be considered as irritating to the skin in vivo, either.

There is data for eye irritation available from an in vitro and an in vivo study performed with Amides, C16-C18 (even numbered).

The in vivo study was conducted in compliance with OECD Guideline 405, although only 2 rabbits were included in the test (Bradshaw, 2010). Nevertheless this study was fully acceptable from a regulatory point of view, as even the contribution of a third animal demonstrating severe irritation reactions would have had no impact on the final classification according to the criteria for eye irritation tests with 3 animals. Therefore, this approach is reasonable considering animal welfare aspects, and the study was chosen as key study. No corneal or iridial effects were observed during the 72-hour observation period of the study. Moderate corneal irritation was noted in the treated eyes of both animals one hour after treatment which had completely reversed until the 24-hour reading. No corneal or iridial effects were observed during the observation period relevant for assessment. Minimal conjunctival irritation in form of erythema and edema was observed at the 24-hour reading; both eyes apperared normal at the 48-hour reading. Due to the lack of any effects after 72 hours the study was terminated then. Considering the mild character and the complete reversibility within 72 hours the test substance was considered to be not irritating to the eyes.

This view is supported by an in vitro study which had been performed using the SkinEthic Reconstructed Human Corneal Epithelium Model (Warren, 2010). The cells of the tissue cultures were exposed to the test substance for 10 minutes. Following a 3-hour incubation period with MTT, cell viability was determined using the colourimetric MTT reduction assay. Based on the lack of effects on cell viability the test substance was considered to be a Non-Irritant in vitro, as well, in accordance with the in vivo assay.

Justification for classification or non-classification

According to the criteria of EU Directive 67/548/EEC and the criteria of Regulation (EC) No 1272/2008 the test substance does not have to be classified as irritating to skin or irritating to the eyes.