N-[3-(dimethylamino)propyl]oleamide

Endpoint summary

Description of key information

The test substance was tested in the in vitro skin corrosion test using a human skin model according to OECD guideline 431. Based on the results, the substance was considered to be not corrosive to the skin. Further information was available from a read-across substance (EMULSAMINE AT-O) which was tested in an in vivo study in rabbits conducted according to OECD guideline 404. It was concluded from the results of this study that the test substance was corrosive when topically applied to rabbit skin.

Additional information

Skin irritation:

Two studies were available to assess the irritant/corrosive potential of Trennmittel ZM 121. The first study (RCC-CCR, 2007) is an in vitro corrosion assay in reconstructed human epidermis which was performed with the test substance (Trennmittel ZM 121) itself according to OECD Guideline 431. The second study (CIT, 2002) is an in vivo test according to OECD guideline 404 which was conducted with EMULSAMINE AT-O, a substance with a similar composition as that of Trennmittel ZM 121 (see table 1 below).

Table 1. Substance descriptions of Trennmittel ZM121 (N-[3 -(Dimethylamino)propyl]oleamide) and EMULSAMINE AT-O (Amides, tall-oil fatty, N-[3 -(dimethylamino)propyl].

	Trennmittel ZM 121	EMULSAMINE AT-O
Purity
Active	>95%	>95%
Free ethylene amine	<1%	<3%
Free fatty acids	<4%	<3%
C-chain distribution
C16	<7%	<6%
C18	>93%	>92%
C20	<3%	<2%
Iodine value (degree of unsaturation, in g I2 per 100 g)	80 -100	100 -120

As indicated in table 1, both substances mainly consist of C18-fatty acid amides, with a slightly higher degree of unsaturation in EMULSAMINE AT-O than in Trennmittel ZM121. Due to the high similarity with regard to composition, EMULSAMINE AT-O is considered acceptable for read across.

The two studies mentioned above were evaluated in a weight of evidence approach to cover the endpoint of skin irritation/corrosion for Trennmittel ZM121.

The corrosive potential of Trennmittel ZM 121 was assessed by means of the Human Skin Model Test according to OECD guideline 431. Two tissues of the human skin model EpiDerm™ each were treated with 50 μl of either the test item, the negative control (deionised water) or the positive control (8 N KOH solution) for 3 minutes and 1 hour, respectively. The mean OD 570 value obtained for the tissue duplicates per substance group were used to calculate a percentage viability relative to the negative control, which was arbitrarily set at 100%. The absolute OD 570 values determined for the negative control tissues were well above the required value of 0.8 for both treatment intervals, thus indicating the quality of the tissues. Treatment with the positive control induced a decrease in the relative absorbance as compared to the negative control to 28.0% for the 3 minutes treatment interval and 11.9% for the 1 hour treatment interval, thus ensuring the validity of the test system. After treatment with the test item Trennmittel ZM 121 the relative absorbance values did not decrease relevantly, neither after 3 minutes nor after 1 hour treatment. Therefore, the test item was considered not corrosive in this assay.

The potential of the test item EMULSAMINE AT-O to induce skin irritation was evaluated in rabbits according to OECD Guideline 404 and in compliance with GLP. In the first instance, the test item was applied for periods of 3 minutes and 4 hours to a single male New Zealand White rabbit. As the test item showed corrosive properties on this first animal, the study was considered complete and the test item was not evaluated on other animals.

A single dose of 0.5 mL of the undiluted test item was applied to the closely-clipped skin of one flank. The test item was held in contact with the skin by means of a semi-occlusive dressing. Cutaneous reactions were observed approximately 1 hour and 24 hours after removal of the dressing.

After a 3-minute or a 4-hour exposure, necrosis was noted at the application site 24 hours after removal of the dressing. The animal was then killed for ethical reasons. It was concluded that, under the experimental conditions chosen, the test item is corrosive when applied topically to rabbits.

According to Regulation (EC) No 1272/2008 (CLP), section 1.1.1.3, "a weight of evidence determination means that all available information bearing on the determination of hazard is considered together, such as the results of suitable in vitro tests, relevant animal data, information from the application of the category approach (grouping, read-across), (Q)SAR results, human experience (...). The quality and consistency of the data shall be given appropriate weight." In general, in vivo data from animal studies can be considered more reliable than in vitro data. The two available studies give contradictory results, but in light of the above-mentioned, the in vivo study according to OECD 404 is given more weight than the in vitro study according to OECD 431, even though the in vitro study was conducted with the actual test substance whereas a read-across substance was tested in the in vivo study. Therefore, Trennmittel ZM121 is considered to be corrosive to the skin.

Justification for classification or non-classification

Based on the available information, Trennmittel ZM121 is considered to be corrosive to the skin. The substance is classified as skin corrosive category 1B (H314 - Causes severe skin burns and eye damage) according to Regulation (EC) No 1272/2008 (CLP) based on the results of an irritation study in rabbits conducted according to OECD guideline 404.