Octanoic acid, compound with 2,2',2''-nitrilotriethanol (1:1)

Skin irritation / corrosion

Administrative data

Endpoint:

skin corrosion: in vitro / ex vivo

Type of information:

experimental study

Adequacy of study:

key study

Study period:

Feb 2019

Reliability:

1 (reliable without restriction)

Rationale for reliability incl. deficiencies:

guideline study

Justification for type of information:

The is a OECD 431 guideline study conducted in accordance with GLP on the substance Octanoic acid, compound with 2,2',2''-nitrilotriethanol (1:1), which has been a Klimisch rating of 1.

Data source

Reference

Reference Type:

study report

Title:

Unnamed

Year:

2019

Report date:

2019

Materials and methods

Test guideline

Qualifier:

according to guideline

Guideline:

OECD Guideline 431 (In Vitro Skin Corrosion: Reconstructed Human Epidermis (RHE) Test Method)

GLP compliance:

yes (incl. QA statement)

Test material

Test material information

Constituent 1

Reference substance name:

Octanoic acid, compound with 2,2',2''-nitrilotriethanol (1:1)

EC Number:

245-327-1

EC Name:

Octanoic acid, compound with 2,2',2''-nitrilotriethanol (1:1)

Cas Number:

22919-56-8

Molecular formula:

C8H16O2.C6H15NO3

IUPAC Name:

2-[bis(2-hydroxyethyl)amino]ethan-1-ol; octanoic acid

Test material form:

liquid: viscous

Specific details on test material used for the study:

Batch 1115-80.

In vitro test system

Test system:

human skin model

Source species:

human

Cell type:

non-transformed keratinocytes

Justification for test system used:

The EpiDermTM skin model and assay for skin corrosion testing is endorsed by OECD TG 431.

Details on test system:

The reconstructed human epidermal model EpidermTM (EPI-200 MatTek Corporation) consists of normal human-derived epidermal keratinocytes which have been cultured to form a multi-layered highly differential model of the human epidermis. It consists of organised basal, spinous and granular layers and a multi-layered stratum corneum containing intercellular lamellar lipid layers arranged in patterns analogous to those found in vivo.

Control samples:

yes, concurrent negative control

yes, concurrent positive control

Amount/concentration applied:

Single topical application of 50µl of test item, negative control (water) or positive control (potassium hydroxide) was applied to the surface of the EpiDerm(TM) skin models.

Duration of treatment / exposure:

3 and 60 minutes at 37°C, 5% CO2, ≥95% RH (Relative Humidity).

Number of replicates:

Three tissues per condition (n=3).

Results and discussion

In vitro

Results

Results 1

Irritation / corrosion parameter:

% tissue viability

Run / experiment:

Viability after 3 minutes

Value:

ca. 84.23

Negative controls validity:

valid

Positive controls validity:

valid

Remarks on result:

no indication of irritation

Results 2

Irritation / corrosion parameter:

% tissue viability

Run / experiment:

Viability after 1 hour

Value:

ca. 5.37

Negative controls validity:

valid

Positive controls validity:

valid

Remarks on result:

positive indication of irritation

Any other information on results incl. tables

Cell viability measurements after 3 minutes of application.

3 Minute Endpoint		NC	PC	TA1
Tissue 1	Aliquot 1 OD	2.38	0.14	2.23
	Aliquot 2 OD	2.38	0.13	2.18
Tissue 2	Aliquot 1 OD	2.50	0.22	1.69
	Aliquot 2 OD	2.57	0.22	1.64
Tissue 3	Aliquot 1 OD	2.31	0.06	2.21
	Aliquot 2 OD	2.30	0.07	2.22
All tissues	Average OD	2.41	0.14	2.03
	Average % Viability	100.00	5.82	84.23
	Average % SD	4.01	2.63	10.71
	Average % CV	4.01	45.10	12.71

NC: negative control (H₂O), PC: Positive control (KOH 8N), TA1: Octanoic Acid Triethanolamine Salt. *CV value of the PC is above 30% (45.10%) however, as the percentage of viability is below 20% (5.82%) acceptance criterion 3 is met.

Cell viability measurements after 1 hour of application.

1 Hour Endpoint		NC	PC	TA1
Tissue 1	Aliquot 1 OD	2.18	0.12	0.15
	Aliquot 2 OD	2.20	0.11	0.14
Tissue 2	Aliquot 1 OD	2.08	0.21	0.09
	Aliquot 2 OD	2.03	0.23	0.08
Tissue 3	Aliquot 1 OD	1.95	0.02	0.10
	Aliquot 2 OD	2.04	0.03	0.10
All tissues	Average OD	2.08	0.12	0.11
	Average % Viability	100.00	5.75	5.37
	Average % SD	4.01	3.76	1.18
	Average % CV	4.01	65.52*	22.06

NC: negative control (H₂O), PC: Positive control (KOH 8N), TA1: Octanoic Acid Triethanolamine Salt. *CV value of the PC is above 30% (65.52%) however, as the percentage of viability is below 20% (5.75%) acceptance criterion 3 is met (as per OECD TG431).

Evalutation of the results - Results were checked against the following acceptance criteria:

		Actual values	Pass/Fail
Acceptance criterion 1	The mean OD570of the negative control tissues must be ≥0.8.	3 min = 2.41 1 hr = 2.08	Pass
Acceptance criterion 2	The mean relative percentage viability of the positive control, after 1hour exposure must be < 15% of the mean of the negative control.	5.75	Pass
Acceptance criterion 3	In the range between 20% and 100% viability, the coefficient of variation (CV) is an additional acceptance criterion.It should not exceed 0.3(30%).	CV 3 minutes 1 hour NC 4.01 4.01 PC 45.10* 65.52* TA1 12.71 22.06	Pass

*Note that the CV values of the PC after 3 min and 1hr were above 30% (45.10% and 65.52% respectively). However, as the percentage of cell viability was below 20% (5.82% and 5.75% respectively), acceptance criterion 3 was met (as per OECD TG431).

 Results Summary

Test item	Test Item ID	Viability after 3 minutes application (% to negative control)	Viability ≥ 50% after 3 minutes (Yes/No)	Viability after 1h application (% to negative control)	Viability ≥ 15% after 1 hour (Yes/No)	Corrosive (C) / Non corrosive (NC)
Octanoic Acid Triethanolamine Salt	TA1	84.23	Yes	5.37	No	Corrosive

Applicant's summary and conclusion

Interpretation of results:

Category 1 (corrosive) based on GHS criteria

Conclusions:

After a 3 minute and 1 hour exposure on the surface of EpiDermTM reconstructed human epidermis, the viability of the tissues was assessed and compared to a negative control. The percentage viabilities obtained after 3 minutes and 1hr were 84.23% and 5.37% respectively and therefore Octanoic acid, compound with 2,2',2''-nitrilotriethanol (1:1) is classified as Corrosive to human skin, and can be sub-categorised as 1B/1C.

Executive summary:

The skin corrosion potential of Octanoic acid, compound with 2,2',2''-nitrilotriethanol (1:1) was assessed in vitro according to OECD Test Guideline 431 (In Vitro Skin Corrosion: Reconstructed Human Epidermis Test Method). This study was conducted in accordance with GLP and assigned a Klimisch score of 1 using the criteria for assessing data quality set forth by Klimisch et al. (1997)

 

This in vitro assay predicts the skin corrosion potential of a chemical by measurement of its cytotoxic effect on the EpiDerm™ tissue model. The test item is applied directly to the skin surface, cell viability is measured by enzymatic conversion of the vital dye MTT into a blue formazan salt that is quantitatively measured after extraction from the skin tissues.

 

Prior to the execution of the study, the required compatibility checks confirmed that the test item did not interfere with MTT, and following the study results were checked and validated against acceptance criteria.

 

A test item is classified "corrosive", if the relative mean of tissue viability after 3 minute treatment with a test material is decreased below 50%. In addition, those materials classified "non-corrosive" after 3 minute treatment (viability ≥ 50%) are classified "corrosive" if the relative mean of tissue viability after 1 hour treatment with a test material is decreased below 15%.

 

The classification can be then further sub-categorized to 1 A or B/ C. A test item is classified "corrosive, optional Sub-Category 1A", if the relative tissue viability after 3 minute treatment with a test material is decreased below 25%. A test item is classified "corrosive, optional Sub-Category 1B/1C", if the relative tissue viability after 3 minute treatment with a test material is ≥25%.

 

In this study, the percentage viabilities obtained after 3 minutes and 1hr were 84.23% and 5.37% respectively therefore Octanoic acid, compound with 2,2',2''-nitrilotriethanol (1:1) is classified as Corrosive to human skin, and can be sub-categorised as 1B/1C.