3-Butoxy-7-ethoxy-4,6-difluoro-dibenzothiophene

Skin irritation / corrosion

Administrative data

Endpoint:

skin corrosion: in vitro / ex vivo

Type of information:

experimental study

Adequacy of study:

key study

Study period:

Aug 24, 2018 - Nov 26, 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

Test guideline 1

Qualifier:

according to guideline

Guideline:

other: Council Regulation (EC) No. 440/2008 laying down test methods pursuant to Regulation (EC) No. 1907/2006. B.40.bis. In vitro skin corrosion: human skin model test

Deviations:

no

Test guideline 2

Qualifier:

according to guideline

Guideline:

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

Version / remarks:

July 29, 2016

Deviations:

no

Test guideline 3

Qualifier:

according to guideline

Guideline:

other: INVITTOX Protocol SkinEthic Skin Corrosivity Test, April 2012.

Deviations:

no

GLP compliance:

yes (incl. QA statement)

Test material

Test material information

Constituent 1

Reference substance name:

3-Butoxy-7-ethoxy-4,6-difluoro-dibenzothiophene

EC Number:

946-002-3

Cas Number:

1818916-02-7

Molecular formula:

C18H18F2O2S

IUPAC Name:

3-Butoxy-7-ethoxy-4,6-difluoro-dibenzothiophene

Test material form:

solid

In vitro test system

Test system:

human skin model

Source species:

human

Cell type:

non-transformed keratinocytes

Cell source:

foreskin from a single donor

Justification for test system used:

standard model

Vehicle:

unchanged (no vehicle)

Remarks:

No vehicle used in this study; The test item was applied neat to the tissues.

Details on test system:

CELL CULTURE
- Supplier: EpiSkin/SkinEthic Laboratories, Lyon, France)
- Source: human keratinocytes cultured on a polycarbonate filter in conditions which permit their terminal differentiation
- Format: 24 well plate
- Batch: 18-RHE-127
- Expires: Nov 05, 2018

TEMPERATURE USED FOR TEST SYSTEM
- Temperature used during treatment: room temperature
- Temperature of post-treatment incubation: 37°C

REMOVAL OF THE TEST MATERIAL AND CONTROL
At the end of the exposure periods, the test item, positive and negative control was removed immediately by gently rinsing with a minimum volume of 20 mL DPBS using a pipette. Excess DPBS was removed by gently shaking the tissue inserts and blotting the bottom of the tissue inserts with blotting paper.

Control samples:

yes, concurrent negative control

Amount/concentration applied:

TEST MATERIAL
- Amount(s) applied (volume or weight with unit): 20 mg ± 3 mg of solid test material
- Concentration (if solution): n/a

VEHICLE
- Amount(s) applied (volume or weight with unit): n/a
- Concentration (if solution): n/a
- Lot/batch no. (if required): n/a
- Purity: n/a

NEGATIVE CONTROL
- Amount(s) applied (volume or weight): 40 µL ± 3 µl (deionised water )
- Concentration (if solution): n/a

POSITIVE CONTROL
- Amount(s) applied (volume or weight): 40 µL ± 3 µl
- Concentration (if solution): An 8N potassium hydroxide solution dissolved deionised water pure was used as positive control.

Duration of treatment / exposure:

3 min & 1 hour

Number of replicates:

2

Results and discussion

In vitro

Results

Results 1

Irritation / corrosion parameter:

% tissue viability

Run / experiment:

Experiment 1 / Run 1 (3 min)

Value:

92.1

Vehicle controls validity:

not applicable

Remarks:

The test item was applied neat to the tissues

Negative controls validity:

valid

Positive controls validity:

valid

Remarks on result:

other: Non-corrosive

Results 2

Irritation / corrosion parameter:

% tissue viability

Run / experiment:

Experiment 1 / Run 1 (1 hour)

Value:

84.6

Vehicle controls validity:

not applicable

Remarks:

The test item was applied neat to the tissues

Negative controls validity:

valid

Positive controls validity:

valid

Remarks on result:

other: Non-corrosive

Other effects / acceptance of results:

OTHER EFFECTS:
- Visible damage on test system: none
- Direct-MTT reduction: none
- Colour interference with MTT: none

ACCEPTANCE OF RESULTS:

Acceptability of the Quality Control Data of the Skin Model with Reference to Historical Batch Data:

Acceptance Criterion Result
Negative control OD ≥ 0.8 and ≤ 3.0 1.845 to 2.113

Acceptability of the Positive and Negative Control stated by Episkin/SkinEthic Laboratories:

Acceptance Criterion Result
Mean OD negative control ≥ 0.8 and ≤ 3.0 1.907 (3 min)
2.032 (1 hour)

Mean viability positive control < 15% after 1-hour exposure 0.6%

Range between identically treated < 30% 6.7% (3 min)
tissues with test item 3.0% (1 hour)

Acceptability of the Positive and Negative Control based on Historical Data of the Testing Laboratory:

Acceptance Criterion Result
Mean OD negative control ≥ 1.575 (3 min) 1.907 (3 min)
≥ 1.401 (1 hour) 2.032 (1 hour)

Mean viability positive control ≤ 1.02% 0.60%

Negative Control, Positive Control and Test Substance Data Acceptance Criteria stated by the Testing Laboratory:

Group Acceptance Criterion Result
Range between identically Negative control < 30% 6.7% (3 min)
treated tissues 8.3% (1 hour)
Positive control < 30% 75.0% (1 hour)
Test substance < 30% 6.7% (3 min)
3.0% (1 hour)

The range between identically treated tissues with the positive control was >30%, but the OD values were ≤ 0.3

The study met all acceptance criteria.

Any other information on results incl. tables

Group	Time / [min]	Mean OD	Mean Relative viability / [%]
Negative Control	3	1.907	100.0
Negative Control	60	2.032	100.0
Positive Control	60	0.012	0.6
Test Material	3	1.757	92.1
Test Material	60	1.718	84.6

Applicant's summary and conclusion

Interpretation of results:

GHS criteria not met

Remarks:

Non-corrosive

Conclusions:

This study was performed according to GLP and the methods applied are fully compliant with OECD TG 431. Under the conditions of the present study, the test item is not considered to possess a corrosive potential to skin.

Executive summary:

Objective

The objective of the present study was to investigate the potential of the test item to induce skin corrosion in anin vitrohuman skin model.

Study Design

The test item was applied topically to a human reconstructed skin model followed by determination of the cell viability. Cell viability was determined by enzymatic conversion of vital dye MTT into a blue formazan salt and measurement of the formazan salt after extraction from tissues. The percent reduction of cell viability in comparison to untreated negative controls was used to predict the skin corrosion potential.

Duplicates of the human skin RHE-model were treated with the test item or the negative control for 3 minutes and additional 1 hour. Duplicates with the positive control were only treated for
1 hour. 40 ± 3 µL of either the negative control (deionised water) or the positive control (potassium hydroxide, 8N) were applied to the tissues. Before application of 20 ± 3 mg of the solid test item, 20 ± 2 µL of deionised water was spread to the epidermis surface to improve the contact between the test item and the epidermis.

Results

After treatment with the positive control (potassium hydroxide, 8N) the mean viability value was 0.012% and, thus, lower than the historically established threshold of 1.02%. After treatment with the negative control (deionised water) the mean ODs were 1.907 (3 minutes exposure) and 2.032 (1 hour exposure) and, thus, higher than the historically established thresholds of 1.575 and 1.401, respectively. Thus, the acceptance criteria were met.

Following treatment with the test item, the tissue viability was ≥50% after 3 minutes exposure (mean viability: 92.1%) and ≥15% after 1 hour exposure (mean viability: 84.6%),i.e.according to OECD 431 the test item is not considered as corrosive to skin.

Conclusion

Under the conditions of the present study, the test item is not considered to possess a corrosive potential to skin.