Propanamide, N-[4-(2,4-dihydroxyphenyl)-2-thiazolyl]-2-methyl-

Skin irritation / corrosion

Administrative data

Endpoint:

skin corrosion: in vitro / ex vivo

Type of information:

experimental study

Adequacy of study:

key study

Reliability:

1 (reliable without restriction)

Rationale for reliability incl. deficiencies:

guideline study

Data source

Reference

Reference Type:

study report

Title:

Unnamed

Year:

2014

Report date:

2014

Materials and methods

Test guideline

Test guideline 1

Qualifier:

according to guideline

Guideline:

OECD Guideline 431 (In Vitro Skin Corrosion: Human Skin Model Test)

Version / remarks:

adopted in 2013

Deviations:

no

Test guideline 2

Qualifier:

according to guideline

Guideline:

EU Method B.40 (In Vitro Skin Corrosion: Transcutaneous Electrical Resistance Test (TER))

Deviations:

no

GLP compliance:

yes (incl. QA statement)

Remarks:

Landesamt für Umwelt, Wasserwirtschaft und Gewerbeaufsicht, Mainz, Germany

Test material

Test material information

Constituent 1

Reference substance name:

N-[4-(2,4-dihydroxyphenyl)-1,3-thiazol-2-yl]-2-methylpropanamide

EC Number:

807-621-3

Cas Number:

1428450-95-6

Molecular formula:

C13H14N2O3S

IUPAC Name:

N-[4-(2,4-dihydroxyphenyl)-1,3-thiazol-2-yl]-2-methylpropanamide

Test material form:

solid: particulate/powder

In vitro test system

Test system:

human skin model

Remarks:

EpiDerm™; reconstructed three-dimensional human epidermis (EPI-200)

Cell type:

other: Human-derived epidermal keratinocytes

Cell source:

other: MatTek In Vitro Life Science Laboratories, Bratislava, Slovakia

Vehicle:

water

Details on test system:

REMOVAL OF TEST SUBSTANCE
- Washing: The test substance was washed from the skin surface with phosphate buffered saline.
- Time after start of exposure: 3 and 60 min

CELL VIABILITY MEASUREMENTS
For determining alterations in cell viability, MTT reduction assays were performed. Therefore, tissues were incubated with 300 µL prewarmed MTT solution for 3 h at 37 ± 1°C, 5 ± 1 % CO2 and 80-95 % RH. After aspiration of the MTT solution, tissues were washed several times in phosphate buffered saline followed by tissue drying. Extraction of the formazan product was carried out in 2 mL isopropanol. The optical density was measured at 570 nm wave length in a plate spectrophotometer.

Control samples:

yes, concurrent vehicle

yes, concurrent positive control

Amount/concentration applied:

TEST MATERIAL
- Amount(s) applied: 25 mg ± 2.5 mg moistened with 25 µL demineralized water

POSITIVE CONTROL SUBSTANCE:
- Positive control substance: 8 M KOH

Duration of treatment / exposure:

3 min at room temperature and 60 min at 37 °C in an incubator

Duration of post-treatment incubation (if applicable):

not applicable

Number of replicates:

2

Results and discussion

In vitro

Results

Results 1

Irritation / corrosion parameter:

% tissue viability

Run / experiment:

3 min

Value:

ca. 86.6

Vehicle controls validity:

not examined

Negative controls validity:

valid

Positive controls validity:

valid

Remarks on result:

other: no indication of corrosion

Results 2

Irritation / corrosion parameter:

% tissue viability

Run / experiment:

1 h

Value:

ca. 105.3

Vehicle controls validity:

not examined

Negative controls validity:

valid

Positive controls validity:

valid

Remarks on result:

other: no indication of corrosion

Any other information on results incl. tables

Table 1: MTT assay after 3 minutes exposure

	OD Tissue 1	OD Tissue 2	OD Mean	SD	Viability %	RSD %
Negative Control	1.856 1.840 1.819	1.817 1.802 1.812	1.824	0.02	100	---
Test Substance	1.501 1.645 1.580	1.588 1.588 1.578	1.580	0.05	86.6	0.4
Positive Control	0.409 0.424 0.438	0.431 0.404 0.400	0.418	0.02	22.9	2.0

Table 2: MTT assay after 60 minutes exposure

	OD Tissue 1	OD Tissue 2	OD Mean	SD	Viability %	RSD %
Negative Control	1.515 1.659 1.584	1.867 1.865 1.847	1.723	0.16	100	---
Test Substance	1.871 1.894 1.867	1.754 1.757 1.747	1.815	0.07	105.3	4.9
Positive Control	0.141 0.141 0.141	0.163 0.161 0.161	0.151	0.01	8.8	9.7

Table 3: Historical Control Data

Parameter	OD Negative Control	OD Negative Control	Viability % Positive Control	Viability % Positive Control
Incubation Time	3 min	60 min	3 min	60 min
Mean	1.936	1.920	27.2	14.1
SD	0.157	0.168	5.6	4.4
Range	1.614 – 2.355	1.598 – 2.326	20.2 – 43.6	8.5 – 24.2

Applicant's summary and conclusion

Interpretation of results:

GHS criteria not met

Conclusions:

There is regulatory acceptance in the EU that a substance can be considered corrosive (Skin Corrosive Cat. 1A) based on a positive result in the human epidermis model test. Negative in vitro corrosivity responses are not conclusive with respect to non-classification or classification as irritant and shall therefore be subject to further evaluation.

Executive summary:

One valid experiment was performed.

Two tissues of the human skin model EpiDerm TM were treated with N-[4-(2,4-dihydroxyphenyl)

thiazol-2-yl]isobutyramide for three minutes and one hour, respectively. In average,

24. 7 mg of the solid test item were applied to each tissue and spread to match the tissue

size.

Demineralised water was used as negative Qontrol, 8 M KOH was used as positive control.

After treatment, the respective substance was rinsed from the tissue; then, cell viability of

the tissues was evaluated by addition of MTT which can be reduced to a blue formazan.

Formazan production was measured by measuring the optical density (OD) of the resulting

solution.

After treatment with the negative control, the absorbance values were within the required

acceptability criterion of mean OD ~ 0.8 and !5 2.8 for both treatment intervals thus showing

the quality of the tissues. The positive control showed clear corrosive effects for both

treatment intervals.

After three minutes treatment with the test item, the relative absorbance values were reduced

to 86.6 %. This value is well above the threshold for corrosion potential (50 %). After

one hour treatment, relative absorbance values were increased to 105.3 %. This value,

too, is well above the threshold for corrosion potential (15 %). In the guideline, values

greater or equal to the threshold are considered as ''non-corrosive to skin".

Therefore, N-[4-(2,4-dihydroxyphenyl)thiazol-2-yl]isobutyramide is considered as

not corrosive in the Human Skin Model Test.