2-[2,4-bis(tert-pentyl)phenoxy]-N-(3,5-dichloro-4-ethyl-2-hydroxyphenyl)butyramide

Skin irritation / corrosion

Administrative data

Endpoint:

skin corrosion: in vitro / ex vivo

Type of information:

experimental study

Adequacy of study:

key study

Study period:

October 2018

Reliability:

1 (reliable without restriction)

Rationale for reliability incl. deficiencies:

guideline study

Data source

Reference

Reference Type:

study report

Title:

Unnamed

Year:

2018

Report date:

2018

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:

2-[2,4-bis(tert-pentyl)phenoxy]-N-(3,5-dichloro-4-ethyl-2-hydroxyphenyl)butyramide

EC Number:

300-634-0

EC Name:

2-[2,4-bis(tert-pentyl)phenoxy]-N-(3,5-dichloro-4-ethyl-2-hydroxyphenyl)butyramide

Cas Number:

93951-12-3

Molecular formula:

C28H39Cl2NO3

IUPAC Name:

2-[2,4-bis(tert-pentyl)phenoxy]-N-(3,5-dichloro-4-ethyl-2-hydroxyphenyl)butyramide

Test material form:

solid

Details on test material:

Batch 44029
colour : White to off-white
retest date : 01/06/2019

Specific details on test material used for the study:

Controlled room temperature (15-25°C, <70% relative humidity), protected from light and humidity (store in a tightly closed container)

In vitro test system

Test system:

human skin model

Source species:

human

Cell type:

non-transformed keratinocytes

Cell source:

foreskin from multiple donors

Details on animal used as source of test system:

not applicable

Justification for test system used:

Justification for Selection of the Test System
The EPISKINTM(SM) model has been validated for corrosivity testing in an international trial (Fentem, 1998) and its use is recommended by the relevant OECD guideline for corrosivity testing (OECD No. 431); therefore, it was considered to be suitable for this study.

Vehicle:

unchanged (no vehicle)

Details on test system:

Preparation of the Test Item
The test item was applied as supplied, no formulation was required (although it was grounded to fine powder).

Control samples:

yes, concurrent negative control

yes, concurrent positive control

yes, concurrent MTT non-specific colour control

Amount/concentration applied:

20 mg of powdered test item was applied evenly to the epidermal surface of each of two test units and each additional control skin units and then 100 μL physiological saline solution was added to the test item to ensure good contact with the epidermis

Duration of treatment / exposure:

1 day

Duration of post-treatment incubation (if applicable):

Pre-incubation (Day [-1])
The Maintenance Medium was pre-warmed to 37°C. The appropriate number of wells in an assay plate was filled with the pre-warmed medium (2 mL per well). The epidermis units were placed with the media below them, in contact with the epidermis into each prepared well and then incubated overnight at 37°C in an incubator with 5% CO2 in a >95% humidified atmosphere.

Number of replicates:

In this assay, two replicates for test item were used. Two negative controls and two positive controls were also run in this assay. Furthermore, as the test item was coloured, two additional test item-treated living tissues were used for the non-specific OD evaluation.

Results and discussion

In vitro

Results

Results 1

Irritation / corrosion parameter:

% tissue viability

Run / experiment:

1

Value:

101.2

Vehicle controls validity:

not applicable

Negative controls validity:

valid

Positive controls validity:

valid

Remarks on result:

no indication of irritation

Results 2

Irritation / corrosion parameter:

% tissue viability

Run / experiment:

2

Value:

111.2

Vehicle controls validity:

not applicable

Negative controls validity:

valid

Positive controls validity:

valid

Remarks on result:

no indication of irritation

Any other information on results incl. tables

The results of the optical density (OD) was measured at 570 nm. The mean OD value for the test item treated skin samples showed a 106.2% relative viability compared to the negative control.

Applicant's summary and conclusion

Interpretation of results:

GHS criteria not met

Conclusions:

Following exposure with 80ACQ, the mean cell viability was 106.2% compared to the negative control. This is above the threshold of 35%, therefore the test item was considered as being non-corrosive. The experiment met the validity criteria, therefore the study was considered to be valid.

In conclusion, in this in vitro EPISKIN™(SM) model test with 80ACQ (Batch number: 44029), the results indicate that the test item is non-corrosive to the skin.

Executive summary:

An in vitro skin corrosivity test of the test item was performed in a reconstructed human epidermis model. EPISKINTM(SM) is designed to predict and classify the corrosive potential of chemicals by measuring its cytotoxic effect as reflected in the MTT (3-(4,5-Dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide) assay . The corrosivity of the test item was evaluated according to the OECD No. 431 guideline.

Disks of EPISKINTM(SM) (two units) were treated with the test item and incubated for 4 hours at room temperature. Exposure of test material was terminated by rinsing with Phosphate Buffered Saline solution. The viability of each disk was assessed by incubating the tissues for 3 hours with MTT solution. The precipitated formazan crystals were then extracted using acidified isopropanol and quantified spectrophotometrically.

Physiological saline (0.9% (w/v) NaCl solution) and glacial acetic acid treated epidermis were used as negative and positive controls, respectively (two units / control). Two additional disks were used to provide an estimate of colour contribution (NSCliving%) from the test item. For each treated tissue viability was expressed as a % relative to the negative control. If the mean relative viability after 4 hours of exposure is below 35% of the negative control, the test item is considered to be corrosive to skin.

Following exposure with 80ACQ, the mean cell viability was 106.2% compared to the negative control.