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

Endpoint summary

Description of key information

For the assessment of irritation / corrosion in vitro methods have been applied. The following results have been obtained:

OECD 431: not corrosive to skin

OECD 439: not irritating to skin

OECD 492: not irritating to eye

Key value for chemical safety assessment

Skin irritation / corrosion

Link to relevant study records

Reference

Reference 1

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

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

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

Qualifier:

according to guideline

Guideline:

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

Deviations:

no

GLP compliance:

yes (incl. QA statement)

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

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

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.

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

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.

Reference 2

Endpoint:

skin irritation: in vitro / ex vivo

Type of information:

experimental study

Adequacy of study:

key study

Study period:

Mar 29, 2019 - Feb 26, 2019

Reliability:

1 (reliable without restriction)

Rationale for reliability incl. deficiencies:

guideline study

Qualifier:

according to guideline

Guideline:

EU Method B.46 (In Vitro Skin Irritation: Reconstructed Human Epidermis Model Test)

Version / remarks:

Council Regulation (EC) No. 761/2009 laying down test methods pursuant to Regulation (EC) No. 1907/2006 of the European Parliament and the council on the Registration, Evaluation, Authorisation and Restriction of Chemicals (REACH).

Deviations:

no

Qualifier:

according to guideline

Guideline:

OECD Guideline 439 (In Vitro Skin Irritation: Reconstructed Human Epidermis Test Method)

Version / remarks:

2010

Deviations:

no

Qualifier:

according to guideline

Guideline:

other: Skinethic skin irritation test -42bis Standard operating procedure (SOP) 2009

Deviations:

no

GLP compliance:

yes (incl. QA statement)

Specific details on test material used for the study:

TREATMENT OF TEST MATERIAL PRIOR TO TESTING
No pre-treatment; the test item was applied undiluted.

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:SkinEthic Laboratories (Lyon, France)
- Source: human keratinocytes cultured on a polycarbonate filter in conditions which permit their terminal differentiation
- Format: 24 well plate
- Batch: 19-RHE-032


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
After the end of the treatment interval, the residual test item was removed immediately by gently rinsing with a minimum volume of 25 mL PBS using a pipette. Excess PBS was removed by gently shaking the inserts and blotting the bottom with blotting paper.

DYE BINDING METHOD
- Dye used in the dye-binding assay: MTT
- Spectrophotometer:ELx800, BioTek Instruments GmbH, Bad Friedrichshall, Germany at 570 nm

Control samples:

yes, concurrent negative control

Amount/concentration applied:

TEST MATERIAL: 16 mg of solid test material
NEGATIVE CONTROL: 16 µL (Phosphate-Buffered Saline)
POSITIVE CONTROL: 16 µL (5% aqueous solution of sodium dodecyl sulfate in deionised water)

Duration of treatment / exposure:

42 min (± 1 minute)

Duration of post-treatment incubation (if applicable):

42 hours (± 1 hour)

Number of replicates:

3

Irritation / corrosion parameter:

% tissue viability

Run / experiment:

Experiment 1 / Run 1

Value:

95.6

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:

no indication of irritation

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:
After treatment with the negative control the absorbance values reached a mean OD of 1.668 (SD 2.9%). Therefore, the negative control fulfilled the validity criteria.
Treatment with the positive control revealed a mean relative viability of 1.3% (SD 0.0%), thus the positive control reached the validity criteria.

Group	Time / [min]	Mean OD	Mean Relative viability / [%]
Negative Control	42	1.668	100
Positive Control	42	0.022	1.3
Test Material	42	1.595	95.6

Interpretation of results:

GHS criteria not met

Conclusions:

This study was performed according to GLP and the methods applied are fully compliant with OECD TG 439.Under the experimental conditions reported, the test material is not irritating to the skin.

Executive summary:

The objective of the present study was to investigate the potential of the test item to induce skin irritation in an in vitro human skin model.

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 irritation potential.
Triplicates of the human skin RHE-model were treated with the test item, the negative or the positive control for 42 minutes (± 1 minute). 16 µL of either the negative control (DPBS-buffer) or the positive control (5% aqueous solution of sodium dodecyl sulfate) were applied to the tissues. Before application of 16 mg of the solid test item, 10 µL of deionised water was spread to the epidermis surface to improve the contact between the test item and the epidermis.

All acceptability criteria after treatment with the negative control (DPBS-buffer) and the positive control (5% aqueous solution of sodium dodecyl sulfate) were met.
Following treatment with the test item, the tissue viability was 95.6 % and, thus, higher than 50%, i.e. according to OECD 439 the test item is considered as non-irritant to skin (UN GHS: No Category).

Under the conditions of the present study, the test item is not considered to possess an irritant potential to skin (UN GHS: No Category).

Endpoint conclusion

Endpoint conclusion:

no adverse effect observed (not irritating)

Eye irritation

Link to relevant study records

Reference

Endpoint:

eye irritation: in vitro / ex vivo

Type of information:

experimental study

Adequacy of study:

key study

Study period:

Dec 05, 2018 - Feb 4, 2019

Reliability:

1 (reliable without restriction)

Rationale for reliability incl. deficiencies:

guideline study

Qualifier:

according to guideline

Guideline:

OECD Guideline 492 (Reconstructed Human Cornea-like Epithelium (RhCE) Test Method for Identifying Chemicals Not Requiring Classification and Labelling for Eye Irritation or Serious Eye Damage)

Version / remarks:

October 9, 2017

Deviations:

no

Qualifier:

according to guideline

Guideline:

other: EpiOcular Eye Irritation Test (OCL-200-EIT) for the prediction of acute ocular irritation of chemicals; For use with MatTek Corporation`s Reconstructed Human EpiOcular Model; MatTek Corporation

Version / remarks:

June 29, 2015

Deviations:

no

GLP compliance:

yes (incl. QA statement)

Vehicle:

unchanged (no vehicle)

Controls:

yes, concurrent positive control

yes, concurrent negative control

Amount / concentration applied:

TEST MATERIAL: 50 µL per tissue

NEGATIVE / VEHICLE CONTROL: 50 µL per tissue

Sterile deionized water was used as negative control.

POSITIVE CONTROL: 50 µL per tissue

Designation: Art. 8.09711
Synonym: Methyl acetate
Supplier: Merck KGaA
CAS No.: 79-20-9
Batch No.: S7451611
Appearance: Liquid
Content (GC): 99.6 % (a/a)
Expiry Date: June 30, 2022
Storage conditions: Tightly closed, dark, at room temperature (15 – 25°C)

Duration of treatment / exposure:

30 ± 2 minutes

Number of animals or in vitro replicates:

in vitro: duplicate design

Irritation parameter:

other: Viability %

Run / experiment:

Run 1 / Experiment 1

Value:

96.1

Vehicle controls validity:

valid

Negative controls validity:

valid

Positive controls validity:

valid

Remarks on result:

no indication of irritation

Other effects / acceptance of results:

OTHER EFFECTS:
- Visible damage on test system: No observations

ACCEPTANCE OF RESULTS:
1. The negative control OD is >0.8 and <2.5 (1.978 and 1.916).
2. The mean relative viability of the positive control is below 50% of the negative control viability (35.3%).
3. The difference of viability between the two relating tissues of a single chemical is <20% (values between 3.1% to 5.8%) in the same run (for positive and negative control tissues and tissues of single chemicals).

The study met all acceptance criteria.

	Mean OD	Mean Viability
Negative Control	1.874	100.0%
Positive Control	0.330	17.6%
Test Item	1.888	100.7%

Interpretation of results:

GHS criteria not met

Conclusions:

Under the conditions of the present study, the test item did not show an eye hazard potential. The test item is identified as not requiring classification and labeling according to UN GHS (No Category).

Executive summary:

Objective

The objective of the present study was to investigate the potential of the test item to induce eye irritation in anin vitrohuman cornea model.

Study Design

The test item was applied topically to a reconstructed human cornea-like epithelium model (EpiOcular) 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 eye irritation potential.

Duplicates of the EpiOcular-model were treated with the test item, the negative or the positive control for 6 hours (± 15 minutes). 50 mg of the test item and 50 µL of either the negative control (sterile deionized water) or the positive control (methyl acetate) were applied to the tissues.

Results

After treatment with the negative control (sterile deionized water) the mean OD was 1.888 (study acceptance criterion: >0.8 and <2.5). Treatment with the positive control (methyl acetate) revealed a mean viability value of 17.6% (study acceptance criterion: <50%). Thus, the acceptance criteria were met.

Following treatment with the test item the test material, the tissue viability was 100.7% and, thus, higher than 60%, i.e. according to OECD 492 the test item is identified as not requiring classification and labeling according to UN GHS (No Category).

Conclusion

Under the conditions of the present study, the test item did not show an eye hazard potential. The test item is identified as not requiring classification and labeling according to UN GHS (No Category).

Endpoint conclusion

Endpoint conclusion:

no adverse effect observed (not irritating)

Respiratory irritation

Endpoint conclusion

Endpoint conclusion:

no study available

Justification for classification or non-classification

Based on the provided information the test item is not classified for skin and eye irritation/corrosion according to the EU Regulation (EC) No 1272/2008 on Classification, Labelling and Packaging of Substances and Mixtures.