1,3-Benzenedimethanamine, reaction products with glycidyl tolyl ether

Endpoint summary

Description of key information

In vitro skin corrosion study according to OECD guideline 431 (In vitro skin Corrosion: Reconstructed Human Epidermis Test Method). Upon inspection of the results, the test item was considered to be non-corrosive to the skin.

The test item was classified as irritant.  The following classification criteria apply:

EU CLP and UN GHS Hazard statement H315 “Causes Skin Irritation” Category 2.

Category 1. UN GHS or EU CLP Causes serious eye damage.

Key value for chemical safety assessment

Skin irritation / corrosion

Link to relevant study records

Reference

Reference 1

Endpoint:

skin irritation / corrosion

Remarks:

in vitro

Type of information:

experimental study

Adequacy of study:

supporting study

Study period:

This study was conducted between 17 May 2017 and 19 May 2017

Reliability:

1 (reliable without restriction)

Rationale for reliability incl. deficiencies:

guideline study

Qualifier:

according to guideline

Guideline:

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

Version / remarks:

28 July 2015

Deviations:

no

GLP compliance:

yes (incl. QA statement)

Specific details on test material used for the study:

Identification : 1,3-Benzenedimethanamine, reaction products with glycidyl tolyl ether
Batch : WA 1508
Purity : Not supplied
Physical state/Appearance: Clear colourless viscous liquid
Expiry Date : 01 January 2021
Storage Conditions: Room temperature in the dark

Test system:

human skin model

Source species:

human

Cell type:

other: epithelial, derived from human skin, and formed into a stratified, cornified epithelium.

Details on test system:

Test System
EpiDerm™ Reconstructed Human Epidermis Model Kit
Supplier : MatTek
Date received : 16 May 2017
EpiDermTM Tissues (0.63cm2) lot number : 25812
Assay Medium lot number : 051117ALA
Upon receipt of the EpidermTM tissues, the sealed 24 well plate was stored in a refrigerator until use.

Control samples:

yes, concurrent negative control

yes, concurrent positive control

Amount/concentration applied:

50 µL test item and controls

Duration of treatment / exposure:

3 minutes and 60 minutes

Duration of post-treatment incubation (if applicable):

3 hours

Number of replicates:

2

Details on study design:

Study Design
Pre-Test Procedure

Assessment of Direct Test Item Reduction of MTT

MTT Dye Metabolism, Cell Viability Assay
The MTT assay, a colorimetric method of determining cell viability, is based on reduction of the yellow tetrazolium salt (3-[4,5-dimethylthiazol-2-yl]-2,5-diphenyl-tetrazolium bromide) to a blue formazan dye by mitochondrial succinate dehydrogenase in viable cells.
One limitation of the assay is possible interference of the test item with MTT. A test item may directly reduce MTT, thus mimicking dehydrogenase activity of the cellular mitochondria. This property of the test item is only a problem if at the time of the MTT test (after rinsing) there is still a sufficient amount of the test item present on or in the tissues. In this case, the true metabolic MTT reduction and the false direct MTT reduction can be differentiated and quantified.

Test for Direct MTT Reduction
As specified, a test item may interfere with the MTT endpoint, if it was able to directly reduce MTT and at the same time was present on or in the tissues when the MTT viability test was performed. To identify this possible interference, the test item was checked for the ability to directly reduce MTT according to the procedure below:
50 µL of the test item was added to 1 mL of a freshly prepared 1.0 mg/mL MTT solution. The solution was incubated in the dark at 37 °C, 5% CO2 in air for 60 minutes. Untreated MTT solution was tested concurrently to act as a control.
If the MTT solution containing the test item turns blue/purple relative to the control, the test item was presumed to have reduced the MTT.
The test item was shown to directly reduce MTT in the direct MTT reduction test. There was a possibility that if the test item could not be totally rinsed off the tissues, any residual test item present on or in the tissue may directly reduce MTT and could have given rise to a false negative result. Therefore, the determination of skin corrosion potential was performed in parallel on viable and freeze- killed tissues.
This step was a functional check which employs freeze-killed tissues that possess no metabolic activity but absorb and bind the test item like viable tissues.
Freeze-killed tissues were prepared prior to the study by placing untreated EPIDERMTM tissues in an empty 12 well plate and storing in a freezer (14 to 30 °C) for a minimum of 24 hours. Before use each tissue was thawed by placing in 0.9 mL of assay medium for approximately 1 hour at room temperature.
In addition to the normal test procedure, the MTT reducing test item was applied to two freeze killed tissues per exposure period. In addition, two freeze killed tissues per exposure period remained untreated. The untreated freeze killed control showed a small amount of MTT reduction due to residual reducing enzymes within the killed tissues.

Assessment of Color Interference with the MTT Endpoint
A test item may interfere with the MTT endpoint if it is colored. The MTT assay is affected only if the test item is present in the tissues when the MTT viability assay is performed.
50 µL of test item was added to 300 µL of sterile water. The solution was incubated in the dark at 37 oC, 5% CO2 in air for 60 minutes. A visual assessment of the color was then made.

Main Test
Pre-Incubation
The assay medium was pre-warmed before use. 0.9 mL of this assay medium was pipetted into the appropriate wells of two pre-labeled 6-well plates for both the 3 Minute and 60 Minute exposure periods. EpiDerm™ tissues were transferred into the 6 well plates containing the assay medium. The 6 well plates containing the EpiDerm™ samples were pre-incubated (37 °C, 5% CO2) for approximately 1 hour before dosing.

Application of Test Item and Rinsing
Before pre-incubation was complete, a 24 well plate was prepared for use as a “holding plate” for both the 3 Minute and 60 Minute exposure periods. This plate was used to maintain the viability of the tissue inserts between rinsing following chemical exposure and MTT loading. Another 24 well plate was prepared for the MTT loading. 300 µL of either pre warmed assay medium (holding plate) or MTT medium (MTT loading plate) was dispensed into each well. The two plates were placed into the incubator until required.
After pre incubation of the EpiDerm™ tissues, the medium was aspirated and replaced with 0.9 mL of fresh assay medium. The 6-well plate for the 3 Minute exposure period was returned to the incubator, while the other was being dosed for the 60 Minute exposure. For the 60 Minute exposure period, 50 µL of sterile distilled water (negative control) was added to the first two tissues. The tissues were dosed at regular intervals to allow for the time taken to rinse each tissue following exposure and to ensure that each tissue gets an equal exposure time. 50 µL of the test item and 50 µL of 8.0 N Potassium Hydroxide (positive control) were also applied to the corresponding tissues in turn. 25 µL of sterile water was added for wetting of the test item to increase tissue surface contact. The plate was returned to the incubator (37 °C, 5% CO2) for the 60 Minute exposure period.
When dosing for the 60 Minute exposure period was complete, the same procedure was repeated for the 3 Minute exposure period. Because the exposure time was so short, the tissues were dosed at regular intervals to ensure that each tissue received an equal exposure time and to allow for the time taken to rinse each tissue following exposure. Rinsing was achieved by filling and emptying each tissue under a constant soft stream of DPBS to gently remove any residual test item. Excess DPBS was removed by blotting the bottom of the tissue insert with tissue paper. Each tissue was placed into the prepared holding plate until all tissues were rinsed. They were then blotted and transferred to the 24 well plate prepared for MTT loading. The plate was incubated (37 °C, 5% CO2) for 3 hours. Once the 60 Minute exposure period was complete, the same rinsing and MTT loading procedure was repeated.
After the 3 Hour MTT incubation was complete, the inserts were blotted and transferred to labeled 24 well plates for MTT extraction. 2 mL of MTT extractant (isopropanol) was used to completely immerse each insert and the plate was covered with plate sealer to prevent Isopropanol evaporation. The plates stood overnight at room temperature, to allow extraction to proceed.

Absorbance/Optical Density Measurements
After extraction, each tissue was pierced with a pipette fitted with a 1000 µL tip and the extraction solution was forced vigorously up and down to form a homogenous solution. 3 x 200 µL aliquots of the extract were transferred to the appropriate wells of a pre labeled 96 well plate. 200 µL of isopropanol alone was added to the three wells designated as blanks. Absorbency at 570nm (OD570) of each well was measured using the Labtech LT 4500 microplate reader.

Irritation / corrosion parameter:

% tissue viability

Run / experiment:

3 Miinute

Value:

ca. 70

Negative controls validity:

valid

Remarks:

Set at 100%

Positive controls validity:

valid

Remarks:

4.3

Remarks on result:

other: No indication of corrosion

Irritation / corrosion parameter:

% tissue viability

Run / experiment:

60 Minute

Value:

ca. 25.7

Negative controls validity:

valid

Remarks:

Set at 100%

Positive controls validity:

valid

Remarks:

4.3

Remarks on result:

other: No indication of corrosion

Direct MTT Reduction

An assessment found the test item was able to directly reduce MTT. Therefore, an additional procedure using freeze‑killed tissues was performed. However, the results obtained showed that no interference due to direct reduction of MTT occurred. It was therefore considered unnecessary to use the results of the freeze‑killed tissues for quantitative correction of results or for reporting purposes.

 Assessment of Color Interference with the MTT endpoint

The solution containing the test item did not become colored. This was taken to indicate the test item did not have the potential to cause color interference.

 

Test Item, Positive Control Item and Negative Control Item

Mean OD₅₆₂values and viabilities for the negative control, positive control and test item are given below:

Tissue	Exposure Period	MeanOD570of individual tissues	Mean OD570of duplicate tissues	Standard Deviation	Coefficient of Variation (%)	Relative Mean Viability (%)
Negative Control	3 Minutes	1.636	1.639	0.004	0.3	100*
		1.642
	60 Minutes	1.519	1.577	0.082	5.2
		1.635
Positive Control	3 Minutes	0.085	0.070	0.020	na	4.3
		0.055
	60 Minutes	0.070	0.068	0.003	na	4.3
		0.066
Test Item	3 Minutes	1.169	1.148	0.030	2.6	70.0
		1.126
	60 Minutes	0.453	0.406	0.066	16.4	25.7
		0.359

OD= Optical density

*=          The mean percentage viability of the negative control tissue is set at 100%

na=         Not applicable

The relative mean viabilities of the test item treated tissues were as follows:

 3 minutes exposure: 70.0%

60 minutes exposure: 25.7%

     

Quality Criteria

The mean OD₅₇₀for the negative control treated tissues was 1.639 for the 3‑Minute exposure period and 1.577 for the 60‑Minute exposure period. The negative control acceptance criteria were therefore satisfied.

The relative mean tissue viability for the positive control treated tissues was 4.3% relative to the negative control following the 60‑Minute exposure period. The positive control acceptance criterion was therefore satisfied.

In the range 20 to 100% viability the Coefficient of Variation between the two tissue replicates of each treatment group did not exceed 30%. The acceptance criterion was therefore satisfied

Interpretation of results:

other: Not classified for corrosivity

Conclusions:

The test item was considered to be non-corrosive to the skin.

Executive summary:

The purpose of this test is to evaluate the corrosivity potential of the test item using the EpiDerm™ Human Skin Model after treatment periods of 3 and 60 minutes.

Corrosion is directly related to cytotoxicity in the EpiDerm™ tissue. Cytotoxicity is determined by the reduction of MTT (3-[4,5-dimethylthiazol-2-yl]-2,5-diphenyl-tetrazolium bromide) to formazan by viable cells in the test item treated tissues relative to the corresponding negative control. The results are used to make a prediction of the corrosivity potential of the test item.

Methods

Duplicate tissues were treated with the test item for exposure periods of 3 and 60 minutes. Negative and positive control groups were treated for each exposure period. The test item was found to directly reduce MTT and therefore additional non-viable tissues were incorporated into the testing for correction purposes. At the end of the exposure period the test item was rinsed from each tissue before each tissue was taken for MTT‑loading. After MTT loading each tissue was placed in 2 mL Isopropanol for MTT extraction.

At the end of the formazan extraction period each well was mixed thoroughly and triplicate 200 mL samples were transferred to the appropriate wells of a pre-labeled 96‑well plate. The optical density (OD) was measured at 570 nm (OD₅₇₀).

Data are presented in the form of percentage viability (MTT reduction in the test item treated tissues relative to negative control tissues).

Results

The relative mean viabilities for each treatment group were as follows:

Exposure Period		Percentage Viability
		Negative Control		Positive Control		Test Item
3 minute		100*		4.3		70.0
60 minute		100*		4.3		25.7

*The mean viability of the negative control tissues is set at 100%

Quality criteria: The quality criteria required for acceptance of results in the test were satisfied.

Conclusion

The test item was considered to be non-corrosive to the skin.

Reference 2

Endpoint:

skin irritation: in vitro / ex vivo

Type of information:

experimental study

Adequacy of study:

key study

Study period:

This study was conducted between 31 May 2017 and 19 June 2017

Reliability:

1 (reliable without restriction)

Rationale for reliability incl. deficiencies:

other: The study is considered to be reliability 1 as it has been conducted according to OECD Test Guideline 439 using the EPISKIN™ Reconstructed Human Epidermis Model and in compliance with GLP.

Qualifier:

according to guideline

Guideline:

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

Version / remarks:

28 July 2015

Deviations:

no

Qualifier:

according to guideline

Guideline:

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

Version / remarks:

23 July 2009

Deviations:

no

GLP compliance:

yes (incl. QA statement)

Specific details on test material used for the study:

Information as provided by the Sponsor.
Identification: 1,3-Benzenedimethanamine, reaction products with glycidyl tolyl ether
Batch: WA 1508
Purity: Not supplied
Physical state/Appearance: Clear colorless liquid
Expiry Date: 01 January 2021
Storage Conditions: Room temperature in the dark

Test system:

human skin model

Source species:

human

Cell type:

non-transformed keratinocytes

Justification for test system used:

The EPISKIN™ model is a three-dimensional reconstructed human epidermis model consisting of adult human-derived epidermal keratinocytes seeded on a dermal substitute consisting of a collagen type I matrix coated with type IV collagen. A highly differentiated and stratified epidermis model is obtained after a 13 Day culture period comprising of the main basal, supra basal, spinous and granular layers and a functional stratum corneum.
Following a full validation study the EpiSkinTM reconstructed human epidermis model showed evidence of being a reliable and relevant stand-alone test for predicting rabbit skin irritation when the endpoint is measured by MTT reduction and for being used as a replacement for the Draize Skin Irritation Test for the purpose of distinguishing between Irritating and Non-Irritating test items.
The procedure followed is based on the recommended EpiSkin™ SOP, Version 1.8 (February 2009), ECVAM Skin Irritation Validation Study.
Test items are applied topically as the dermal route is the most likely exposure route and the results of the study are believed to be of value in predicting the likely skin irritancy potential to man.

Vehicle:

unchanged (no vehicle)

Details on test system:

EPISKIN™ Reconstructed Human Epidermis Model Kit
Supplier : SkinEthic Laboratories, Lyon, France
Date received : 13 June 2017
EpiSkinTM Tissues (0.38cm2) lot number : 17-EKIN-024
Maintenance Medium lot number : 17-MAIN3-024
Assay Medium lot number : 17-ESSC-023

Study Design
Pre-Test Procedure
Assessment of Direct Test Item Reduction of MTT
MTT Salt Metabolism, Cell Viability Assay
The MTT assay, a colorimetric method of determining cell viability, is based on reduction of the yellow tetrazolium salt (3-[4,5-dimethylthiazol-2-yl]-2,5-diphenyl-tetrazolium bromide) to a blue/purple formazan salt by mitochondrial succinate dehydrogenase in viable cells.
One limitation of the assay is possible interference of the test item with MTT. A test item may directly reduce MTT, thus mimicking dehydrogenase activity of the cellular mitochondria. This property of the test item is only a problem, if at the time of the MTT test (after rinsing) there are still sufficient amounts of the test item present on or in the tissues. In this case, the true metabolic MTT reduction and the false direct MTT reduction can be differentiated and quantified by using killed tissues to act as controls.

Test for Direct MTT Reduction
As specified, a test item may interfere with the MTT endpoint, if it is able to directly reduce MTT and at the same time is present on or in the tissues when the MTT viability test is performed. To identify this possible interference, the test item is checked for the ability to directly reduce MTT according to the following procedure:
10 µL of the test item was added to 2 mL of a 0.3 mg/mL MTT solution freshly prepared in assay medium. The solution was incubated in the dark at 37”C, 5% CO2 in air for 3 hours. Untreated MTT solution was used as a control.
If the MTT solution containing the test item turns blue/purple, the test item is presumed to have reduced the MTT and the determination of skin irritation potential would be performed in parallel on viable and water-killed tissues for quantitative correction of the results.
The test item was shown to directly reduce MTT in the direct MTT reduction test. There was a possibility that if the test item could not be totally rinsed off the tissues, any residual test item present on or in the tissue may directly reduce MTT and could have given rise to a false negative result. Therefore, the determination of skin irritation potential was performed in parallel on viable and water-killed tissues.
This step was a functional check which employs water-killed tissues that possess no metabolic activity but absorb and bind the test item like viable tissues.
Water-killed tissues were prepared prior to the study by placing untreated EPISKINTM tissues in a 12-well plate containing 2.0 mL of sterile distilled water in each well. The tissues were incubated at 37”C, 5% CO2 in air for 48 ± 1 hours. At the end of the incubation the water was discarded. Once killed the tissues were stored in a freezer (-14 to -30 °C) for up to
6 months. Before use each tissue was thawed by placing in 2.0 mL of maintenance medium for approximately 1 hour at room temperature.
In addition to the normal test procedure, the MTT reducing test item was applied to three water-killed tissues. In addition, three water-killed tissues remained untreated. The untreated water-killed control showed a small amount of MTT reduction due to residual reducing enzymes within the killed tissues.

Assessment of Color Interference with the MTT endpoint
A test item may interfere with the MTT endpoint if it is colored. The MTT assay is affected only if the test item is present in the tissues when the MTT viability assay is performed.
10 µL of test item was added to 90 µL of sterile water. After mixing for 15 minutes on a plate shaker a visual assessment of the color was made.

Pre-incubation (Day 0: Tissue Arrival)
Before removal from the transport plate each tissue was inspected for any air bubbles between the agarose gel and the insert:
Tissues Satisfactory : Yes
Temperature Indicator Color Satisfactory : Yes
Agar Medium Color Satisfactory : Yes
2 mL of maintenance medium, warmed to approximately 37 °C, was pipetted into the first column of 3 wells of a pre-labeled 12-well plate. Each epidermis unit was transferred into the maintenance medium filled wells (3 units per plate). A different 12-well plate was used for the test item and each control item. The tissues were incubated at 37 °C, 5% CO2 in air overnight.

Main Test
Application of Test Item and Rinsing (Day 1)
2 mL of maintenance medium, warmed to approximately 37”C, was pipetted into the second column of 3 wells of the 12-well plate.
Triplicate tissues were treated with the test item for an exposure period of 15 minutes. The test item was applied topically to the corresponding tissues ensuring uniform covering. 10 µL (26.3 µL/cm2) of the test item was applied to the epidermis surface. Triplicate tissues treated with 10 µL of DPBS served as the negative controls and triplicate tissues treated with 10 µL of SDS 5% w/v served as the positive controls. To ensure satisfactory contact with the positive control item the SDS solution was spread over the entire surface of the epidermis using a pipette tip (taking particular care to cover the center). After a 7-Minute contact time the SDS solution was re-spread with a pipette tip to maintain the distribution of the SDS for the remainder of the contact period (re-spreading is not required for the negative control or test item). The plates were kept in the biological safety cabinet at room temperature for 15 minutes.
At the end of the exposure period, each tissue was removed from the well using forceps and rinsed using a wash bottle containing DPBS with Ca++ and Mg++. Rinsing was achieved by filling and emptying each tissue insert for approximately 40 seconds using a constant soft stream of DPBS to gently remove any residual test item. The rinsed tissues were transferred to the second column of 3 wells containing 2 mL of maintenance medium in each well. The rinsed tissues were incubated at 37”C, 5% CO2 in air for 42 hours.

MTT Loading/Formazan Extraction (Day 3)
Following the 42-Hour post-exposure incubation period each 12-well plate was placed onto a plate shaker for 15 minutes to homogenize the released mediators in the maintenance medium. 1.6 mL of the maintenance medium from beneath each tissue was transferred to pre-labeled micro tubes and stored in a freezer at -14 to -30 ºC for possible inflammatory mediator determination.
2 mL of a 0.3 mg/mL MTT solution, freshly prepared in assay medium, was pipetted into the third column of 3 wells of the 12-well plates. The tissues were transferred to the MTT filled wells, being careful to remove any excess maintenance medium from the bottom of the tissue insert by blotting on absorbent paper. The tissues were incubated for 3 hours at 37 °C, 5% CO2 in air. At the end of the 3-Hour incubation period each tissue was placed onto absorbent paper to dry. A total biopsy of the epidermis was made using the EPISKINTM biopsy punch. The epidermis was carefully separated from the collagen matrix using forceps and both parts (epidermis and collagen matrix) placed into labeled 1.5 mL micro tubes containing 500 µL of acidified isopropanol, ensuring that both the epidermis and collagen matrix were fully immersed. Each tube was plugged to prevent evaporation and mixed thoroughly on a vortex mixer. The tubes were refrigerated at 1 to 10 °C until Day 6 of the experiment, allowing the extraction of formazan crystals out of the MTT-loaded tissues.

Absorbance/Optical Density Measurements (Day 6)
At the end of the formazan extraction period each tube was mixed thoroughly on a vortex mixer to produce a homogenous colored solution.
For each tissue, duplicate 200 µL samples were transferred to the appropriate wells of a pre-labeled 96-well plate. 200 µL of acidified isopropanol alone was added to the two wells designated as ‘blanks’. The optical density was measured (quantitative viability analysis) at 570 nm (without a reference filter) using the Labtech LT-4500 microplate reader.

Control samples:

yes, concurrent negative control

yes, concurrent positive control

Amount/concentration applied:

TEST MATERIAL
- Amount(s) applied (volume or weight with unit): 10 µL as supplied

NEGATIVE CONTROL
- Amount(s) applied (volume or weight): 10 µL,
- Concentration (if solution): as supplied:

POSITIVE CONTROL
- Amount(s) applied (volume or weight): 10 µL
- Concentration (if solution): as a 5% w/v aqueous solution

Duration of treatment / exposure:

15 Minutes

Duration of post-treatment incubation (if applicable):

42 hours

Number of replicates:

3

Details on study design:

Study Design
Pre-Test Procedure
Assessment of Direct Test Item Reduction of MTT
MTT Salt Metabolism, Cell Viability Assay
The MTT assay, a colorimetric method of determining cell viability, is based on reduction of the yellow tetrazolium salt (3-[4,5-dimethylthiazol-2-yl]-2,5-diphenyl-tetrazolium bromide) to a blue formazan salt by mitochondrial succinate dehydrogenase in viable cells.
One limitation of the assay is possible interference of the test item with MTT. A test item may directly reduce MTT, thus mimicking dehydrogenase activity of the cellular mitochondria. This property of the test item is only a problem, if at the time of the MTT test (after rinsing) there are still sufficient amounts of the test item present on or in the tissues. In this case, the true metabolic MTT reduction and the false direct MTT reduction can be differentiated and quantified by using killed tissues to act as controls.

Test for Direct MTT Reduction
As specified, a test item may interfere with the MTT endpoint, if it is able to directly reduce MTT and at the same time is present on or in the tissues when the MTT viability test is performed. To identify this possible interference, the test item is checked for the ability to directly reduce MTT according to the following procedure:
10 µL of the test item was added to 2 mL of a 0.3 mg/mL MTT solution freshly prepared in assay medium. The solution was incubated in the dark at 37”C, 5% CO2 in air for 3 hours. Untreated MTT solution was used as a control.
If the MTT solution containing the test item turns blue or purple, the test item is presumed to have reduced the MTT and the determination of skin irritation potential would be performed in parallel on viable and water killed tissues for quantitative correction of the results.

Assessment of Color Interference with the MTT endpoint
A test item may interfere with the MTT endpoint if it is colored. The MTT assay is affected only if the test item is present in the tissues when the MTT viability assay is performed.
10 µL of test item was added to 90 µL of sterile water. After mixing for 15 minutes on a plate shaker a visual assessment of the color was made.

Pre-incubation (Day 0: Tissue Arrival)
Before removal from the transport plate each tissue was inspected for any air bubbles between the agarose gel and the insert:
Tissues Satisfactory : Yes
Temperature Indicator Color Satisfactory : Yes
Agar Medium Color Satisfactory : Yes

2 mL of maintenance medium, warmed to approximately 37 °C, was pipetted into the first column of 3 wells of a pre labeled 12 well plate. Each epidermis unit was transferred into the maintenance medium filled wells (3 units per plate). A different 12-well plate was used for the test item and each control item. The tissues were incubated at 37 °C, 5% CO2 in air overnight.

Main Test
Application of Test Item and Rinsing (Day 1)
2 mL of maintenance medium, warmed to approximately 37”C, was pipetted into the second column of 3 wells of the 12 well plate.
Triplicate tissues were treated with the test item for an exposure period of 15 minutes. The test item was applied topically to the corresponding tissues ensuring uniform covering. 10 µL (26.3 µL/cm2) of the test item was applied to the epidermis surface. Triplicate tissues treated with 10 µL of DPBS served as the negative controls and triplicate tissues treated with 10 µL of SDS 5% w/v served as the positive controls. To ensure satisfactory contact with the positive control item the SDS solution was spread over the entire surface of the epidermis using a pipette tip (taking particular care to cover the center). After a 7 Minute contact time the SDS solution was re spread with a pipette tip to maintain the distribution of the SDS for the remainder of the contact period (re-spreading is not required for the negative control or test item). The plates were kept in the biological safety cabinet at room temperature for 15 minutes.
At the end of the exposure period, each tissue was removed from the well using forceps and rinsed using a wash bottle containing DPBS with Ca++ and Mg++. Rinsing was achieved by filling and emptying each tissue insert for approximately 40 seconds using a constant soft stream of DPBS to gently remove any residual test item. The rinsed tissues were transferred to the second column of 3 wells containing 2 mL of maintenance medium in each well. The rinsed tissues were incubated at 37”C, 5% CO2 in air for 42 hours.

MTT Loading/Formazan Extraction (Day 3)
Following the 42 Hour post-exposure incubation period each 12-well plate was placed onto a plate shaker for 15 minutes to homogenize the released mediators in the maintenance medium. 1.6 mL of the maintenance medium from beneath each tissue was transferred to pre labeled micro tubes and stored in a freezer at 14 to 30 ºC for possible inflammatory mediator determination.
2 mL of a 0.3 mg/mL MTT solution, freshly prepared in assay medium, was pipetted into the third column of 3 wells of the 12-well plates. The tissues were transferred to the MTT filled wells, being careful to remove any excess maintenance medium from the bottom of the tissue insert by blotting on absorbent paper. The tissues were incubated for 3 hours at 37 °C, 5% CO2 in air. At the end of the 3 Hour incubation period each tissue was placed onto absorbent paper to dry. A total biopsy of the epidermis was made using the EPISKINTM biopsy punch. The epidermis was carefully separated from the collagen matrix using forceps and both parts (epidermis and collagen matrix) placed into labeled 1.5 mL micro tubes containing 500 µL of acidified isopropanol, ensuring that both the epidermis and collagen matrix were fully immersed. Each tube was plugged to prevent evaporation and mixed thoroughly on a vortex mixer. The tubes were refrigerated at 1 to 10 °C until Day 6 of the experiment, allowing the extraction of formazan crystals out of the MTT-loaded tissues.

Absorbance/Optical Density Measurements (Day 6)
At the end of the formazan extraction period each tube was mixed thoroughly on a vortex mixer to produce a homogenous colored solution.
For each tissue, duplicate 200 µL samples were transferred to the appropriate wells of a pre labeled 96 well plate. 200 µL of acidified isopropanol alone was added to the two wells designated as ‘blanks’. The optical density was measured (quantitative viability analysis) at 562 nm (without a reference filter) using the Anthos 2001 microplate reader.

Data Evaluation
Quantitative MTT Assessment (Percentage Tissue Viability)
For the test item the relative mean tissue viabilities obtained after the 15 Minute exposure period followed by the 42 Hour post exposure incubation period were compared to the mean of the negative control treated tissues (n=3). The relative mean viabilities were calculated in the following way:

Relative mean viability (%) = (Mean OD562 of test item / Mean OD562 of negative control) x 100

Classification of irritation potential is based upon relative mean tissue viability following the 15 Minute exposure period followed by the 42 Hour post exposure incubation period according toTable 1 below.

Irritation / corrosion parameter:

other: other: relative mean viability

Run / experiment:

15 Minute exposure/42h observation

Value:

> 11.4 - < 22.1

Negative controls validity:

valid

Remarks:

Set to 100%

Positive controls validity:

valid

Remarks:

12.6

Remarks on result:

positive indication of irritation

Remarks:

The test item evoked an irritant result without correction

Other effects / acceptance of results:

Quality Criteria
The relative mean tissue viability for the positive control treated tissues was 12.6% relative to the negative control treated tissues and the standard deviation value of the viability was 1.2%. The positive control acceptance criteria were therefore satisfied.
The mean OD570 for the negative control treated tissues was 0.669 and the standard deviation value of the viability was 2.2%. The negative control acceptance criteria were therefore satisfied.
The standard deviation calculated from individual tissue viabilities of the three identically test item treated tissues was 5.5%. The test item acceptance criterion was therefore satisfied

Direct MTT Reduction

An assessment found the test item was able to directly reduce MTT. Therefore, an additional procedure using water killed tissues was performed in the event that a quantitative correction of the results was necessary. The test item treated water killed tissue group demonstrated significant direct reduction. However, based on the results, the test item would be considered to be positive for skin irritation regardless of whether the water killed tissues were or were not used for correction purposes and therefore the water killed tissue groups were omitted from the final calculations.

It was noted that relative to the negative control, the test item treated water killed tissue group demonstrated significantly higher direct reduction than the viable test item treated group. This is discussed within the discussion section of this report.

Assessment of Color Interference with the MTT endpoint

The solution containing the test item was colorless. It was therefore unnecessary to run color correction tissues.

Test Item, Positive Control Item and Negative Control Item

The individual, mean and corrected mean OD₅₇₀values, standard deviations and tissue viabilities for the test item, negative control item and positive control item are given in Appendix 1. The mean viabilities and standard deviations of the test item and positive control, relative to the negative control are also given in Appendix 1.

The relative mean viability of the test item treated tissues was 16.1% after a 15-Minute exposure period and 42-Hour post-exposure incubation period.

It was considered unnecessary to perform IL-1alph analysis as the results of the MTT test were unequivocal.

Appendix 1: Mean OD570 Values and Percentage Viabilities for the Negative Control Item, Positive Control Item and Test Item

Item	OD570of tissues	Mean OD570of triplicate tissues	± SD of OD570	Relative individual tissue viability (%)	Relative mean viability (%)	± SD of Relative mean viability (%)
Negative Control Item	0.659	0.669	0.015	98.5	100*	2.2
	0.663			99.1
	0.686			102.5
Positive Control Item	0.086	0.084	0.008	12.9	12.6	1.2
	0.075			11.2
	0.091			13.6
Test Item	0.148	0.108	0.037	22.1	16.1	5.5
	0.099			14.8
	0.076			11.4

OD= Optical Densit

SD=        Standard deviation

*=         The mean viability of the negative control tissues is set at 100%

Values obtained from the water-killed tissue groups:

The test item evoked an irritant result without correction and therefore the following calculations were unnecessary to be used for quantitative correction.

 

x̅ (0.629 + 0.613 + 0.713) = 0.652 (tkt) – x̅ (0.351 + 0.335 + 0.314) = 0.333 (ukt) = 0.319

 

0.319 / 0.669 x 100 = 47.7%

 

Therefore, direct MTT reduction relative to the negative control = 47.7%

 

This figure exceeded the 30% cut-off as stated above. However, as the water-killed tissues were not used for quantitatively correcting the results it was irrelevant that the 30% cut-off was exceeded.

  tkt =  treated killed tissues ukt = untreated killed tissues

Interpretation of results:

Category 2 (irritant) based on GHS criteria

Conclusions:

The test item was classified as irritant. The following classification criteria apply:
EU CLP and UN GHS Hazard statement H315 “Causes Skin Irritation” Category 2.

Executive summary:

The purpose of this test was to evaluate the skin irritation potential of the test item using the EPISKIN^TMreconstructed human epidermis model after a treatment period of 15 minutes followed by a post-exposure incubation period of 42 hours. The principle of the assay was based on the measurement of cytotoxicity in reconstructed human epidermal cultures following topical exposure to the test item by means of the colorimetric MTT reduction assay. Cell viability is measured by enzymatic reduction of the yellow MTT tetrazolium salt (3-[4,5-dimethylthiazol-2-yl]-2,5-diphenyl-tetrazolium bromide) to a blue/purple formazan salt (within the mitochondria of viable cells) in the test item treated tissues relative to the negative controls.  

Method

Triplicate tissues were treated with the test item for an exposure period of 15 minutes. The test item was found to directly reduce MTT and therefore additional non-viable, water killed, tissues were incorporated into the testing for correction purposes. At the end of the exposure period each tissue was rinsed before incubating for 42 hours. At the end of the post-exposure incubation period each tissue was taken for MTT-loading. The maintenance medium from beneath each tissue was transferred to pre-labeled micro tubes and stored in a freezer for possible inflammatory mediator determination. After MTT-loading a total biopsy of each epidermis was made and placed into micro tubes containing acidified isopropanol for extraction of formazan crystals out of the MTT-loaded tissues.  

At the end of the formazan extraction period each tube was mixed thoroughly and duplicate 200 µL samples were transferred to the appropriate wells of a pre-labeled 96-well plate. The optical density was measured at 570 nm.

Data are presented in the form of percentage viability (MTT reduction in the test item treated tissues relative to negative control tissues).

Results

The relative mean viability of the test item treated tissues was 16.1% after the 15-Minute exposure period and 42-Hours post-exposure incubation period.

An assessment found the test item was able to directly reduce MTT. Therefore, an additional procedure using water killed tissues was performed in the event that a quantitative correction of the results was necessary. The test item treated water killed tissue group demonstrated significant direct reduction. However, based on the results, the test item would be considered to be positive for skin irritation regardless of whether the water killed tissues were or were not used for correction purposes and therefore the water killed tissue groups were omitted from the final calculations.

Quality criteria: The quality criteria required for acceptance of results in the test were satisfied.

Conclusion

The test item was classified as irritant. The following classification criteria apply:

EU CLP and UN GHS Hazard statement H315 “Causes Skin Irritation” Category 2.

Endpoint conclusion

Endpoint conclusion:

adverse effect observed (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:

The study was conducted on 15 June 2017

Reliability:

1 (reliable without restriction)

Rationale for reliability incl. deficiencies:

other: The study is considered to be reliability 1 as it has been conducted according to OECD Test Guideline 437 using the Bovine Corneal Opacity and Permeability Assay method and in compliance with GLP.

Qualifier:

according to guideline

Guideline:

OECD Guideline 437 (Bovine Corneal Opacity and Permeability Test Method for Identifying i) Chemicals Inducing Serious Eye Damage and ii) Chemicals Not Requiring Classification for Eye Irritation or Serious Eye Damage)

Version / remarks:

26 July 2013

Deviations:

no

Qualifier:

according to guideline

Guideline:

EU method B.47 (Bovine corneal opacity and permeability test method for identifying ocular corrosives and severe irritants)

Version / remarks:

EC No. 440/2008

Deviations:

no

GLP compliance:

yes (incl. QA statement)

Specific details on test material used for the study:

Identification: 1,3-Benzenedimethanamine, reaction products with glycidyl tolyl ether
Batch: WA 1508
Purity: not supplied
Physical state/Appearance: clear colorless viscous liquid
Expiry Date: 01 January 2021
Storage Conditions: room temperature in the dark

Species:

other: Eyes from adult cattle

Strain:

other: Not applicable

Details on test animals or tissues and environmental conditions:

Eyes from adult cattle (typically 12 to 60 months old) were obtained from a local abattoir as a by-product from freshly slaughtered animals. The eyes were excised by an abattoir employee after slaughter, and were placed in Hanks’ Balanced Salt Solution (HBSS) supplemented with antibiotics (penicillin at 100 IU/mL and streptomycin at 100 µg/mL). They were transported to the test facility over ice packs on the same day of slaughter. The corneas were prepared immediately on arrival.

Vehicle:

unchanged (no vehicle)

Controls:

yes, concurrent positive control

yes, concurrent negative control

Amount / concentration applied:

0.75 mL of the test item or control items were applied to the cornea.

Duration of treatment / exposure:

10 minutes

Duration of post- treatment incubation (in vitro):

120 Minutes

Number of animals or in vitro replicates:

3 corneas per treatment

Details on study design:

Study Design
Preparation of Corneas
All eyes were macroscopically examined before and after dissection. Only corneas free of damage were used.
The cornea from each selected eye was removed leaving a 2 to 3 mm rim of sclera to facilitate handling. The iris and lens were peeled away from the cornea. The isolated corneas were immersed in a dish containing HBSS until they were mounted in Bovine Corneal Opacity and Permeability (BCOP) holders.
The anterior and posterior chambers of each BCOP holder were filled with complete Eagle’s Minimum Essential Medium (EMEM) without phenol red and plugged. The holders were incubated at 32 ± 1 ºC for 60 minutes. At the end of the incubation period each cornea was examined for defects. Only corneas free of damage were used.

Selection of Corneas and Opacity Reading
The medium from both chambers of each holder was replaced with fresh complete EMEM.
A pre-treatment opacity reading was taken for each cornea using a calibrated opacitometer (Annex 1). The average opacity for all corneas was calculated.
Three corneas with opacity values close to the median value of all corneas were allocated to the negative control. Three corneas were also allocated to the test item and three corneas to the positive control item.

Treatment of Corneas
The EMEM was removed from the anterior chamber of the BCOP holder and 0.75 mL of the test item or control items were applied to the appropriate corneas. The holders were gently tilted back and forth to ensure a uniform application of the item over the entire cornea. Each holder was incubated, anterior chamber uppermost, at 32 ± 1 ºC for 10 minutes.
At the end of the exposure period the test item and control items were removed from the anterior chamber and the cornea was rinsed three times with fresh complete EMEM containing phenol red before a final rinse with complete EMEM without phenol red. The anterior chamber was refilled with fresh complete EMEM without phenol red. A posttreatment opacity reading was taken and each cornea was visually observed.
The holders were incubated, anterior chamber facing forward, at 32 ± 1 ºC for 120 minutes.
After incubation the holders were removed from the incubator, the medium from both chambers was replaced with fresh complete EMEM and a final opacity reading was taken. Each cornea was visually observed.

Application of Sodium Fluorescein
Following the final opacity measurement the permeability of the corneas to sodium fluorescein was evaluated. The medium from the anterior chamber was removed and replaced with 1 mL of sodium fluorescein solution (4 mg/mL). The dosing holes were plugged and the holders incubated, anterior chamber uppermost, at 32 ± 1 ºC for 90 minutes.

Permeability Determinations
After incubation the medium in the posterior chamber of each holder was decanted and retained.
360 µL of media representing each cornea was dispensed into the appropriate wells of a pre-labeled 96-well plate. The optical density was measured (quantitative viability analysis) at 492 nm (without a reference filter) using the Labtech LT-4500 microplate reader.

Histopathology
The corneas were retained after testing for possible conduct of histopathology. Each cornea was placed into a pre-labeled tissue cassette fitted with a histology sponge to protect the endothelial surface. The cassette was immersed in 10% neutral buffered formalin.

Data Evaluation
Results from the two test method endpoints, opacity and permeability, were combined in an empirically derived formula to generate an In Vitro Irritancy Score.

Opacity Measurement
The change in opacity for each cornea (including the negative control) was calculated by subtracting the initial opacity reading from the final opacity reading. These values were then corrected by subtracting the average change in opacity observed for the negative control corneas. The mean opacity value of each treatment group was then calculated by averaging the corrected opacity values of each cornea for that treatment group.

Permeability Measurement
The corrected OD492 was calculated by subtracting the mean OD492 of the negative control corneas from the OD492 value of each treated cornea. The OD492 value of each treatment group was calculated by averaging the corrected OD492 values of the treated corneas for the treatment group.

In Vitro Irritancy Score
The following formula was used to determine the In Vitro Irritancy Score:
In Vitro Irritancy Score = mean opacity value + (15 x mean permeability OD492 value)
Additionally, the opacity and permeability values were evaluated independently to determine whether the test item induced a response through only one of the two endpoints.

Visual Observation
The condition of the cornea was visually assessed post treatment.

Data Interpretation
The test item was classified according to the following prediction model:

IVIS Classification
≤ 3 No category. Not requiring classification to UN GHS or EU CLP
> 3; ≤55 No prediction of eye irritation can be made
> 55 Category 1. UN GHS or EU CLP Causes serious eye damage

Criteria for an Acceptable Test
For an acceptable test the following positive control criterion should be achieved:
Neat ethanol was used for positive control purposes. The test was acceptable if the positive control produced an In Vitro Irritancy Score which fell within two standard deviations of the historical mean collated during 2015 for this testing facility. Therefore the In Vitro Irritancy Score should fall within the range of 27.2 to 53.4.

For an acceptable test the following negative control criteria should be achieved:
Sodium chloride 0.9% w/v was used for negative control purposes. The test was acceptable if the negative control produced an In Vitro Irritancy Score which is less than or equal to the upper limit for background opacity and permeability values during 2015 for bovine corneas treated with the respective negative control. When testing liquids the negative control limit for opacity should be ≤2.8 and for permeability ≤0.115.

Irritation parameter:

in vitro irritation score

Value:

ca. 76.3

Negative controls validity:

valid

Remarks:

0.5

Positive controls validity:

valid

Remarks:

65.5

Remarks on result:

positive indication of irritation

Irritant / corrosive response data:

Corneal epithelium condition
The corneas treated with the test item were cloudy post treatment and post incubation. The corneas treated with the negative control item were clear post treatment and post incubation. The corneas treated with the positive control item were cloudy post treatment and post incubation

In vitro irritancy scores:
The in vitro irritancy score for the test item was 76.3
The in vitro irritancy score for the negative control was 0.5
The in vitro irritancy score for the positive control was 65.5

Other effects:

No other effects were observed

Criterion for an acceptable test

The positive control In VitroIrritancy Score was above the range of 27.2 to 53.4. The positive control acceptance criterion was therefore not satisfied. This is reported as a deviation.

The negative control gave opacity of ≤2.8 and permeability ≤0.115. The negative control acceptance criteria were therefore satisfied.

Table 1 Individual and Mean Corneal Opacity and Permeability Measurements when needed in this detail (delete when editing):

Treatment	Cornea Number			Opacity			Permeability (OD)		In Vitro Irritancy Score
		Pre-Treatment	Post-Treatment	Post Incubation	Post-Incubation - Pre-Treatment	Corrected Value		Corrected Value
Negative Control	2	3	3	3	0		0.013
	3	3	4	4	1		0.016
	5	3	3	3	0		0.013
					0.3*		0.014		0.5
Positive Control	1	5	37	38	33	32.7	2.070	2.056
	4	4	37	43	39	38.7	1.670	1.656
	6	3	41	41	38	37.7	2.140	2.126
						36.3		1.946	65.5
Test Item	7	3	30	72	69	68.7	0.515	0.501
	8	3	35	68	65	64.7	0.613	0.599
	9	3	36	71	68	67.7	0.774	0.760
						67.0		0.620	76.3

OD= Optical density            

* = Mean of the post-incubation -pre‑treatment values          

**= Mean permeability                     

***= Mean corrected value

Table 2 Corneal Epithelium Condition Post Treatment and Post Incubation:

Treatment	Cornea Number	Obser	vation
		Post Treatment		Post Incubation
Negative Control	2	Clear		Clear
	3	Clear		Clear
	5	Clear		Clear
Positive Control	1	Cloudy		Cloudy
	4	Cloudy		Cloudy
	6	Cloudy		Cloudy
Test Item	7	Cloudy		Cloudy
	8	Cloudy		Cloudy
	9	Cloudy		Cloudy

Interpretation of results:

Category 1 (irreversible effects on the eye) based on GHS criteria

Conclusions:

Category 1. UN GHS or EU CLP Causes serious eye damage.

Executive summary:

The purpose of this test was to identify test items that can induce serious eye damage and to identify test items not requiring classification for eye irritation or serious eye damage. The Bovine Corneal Opacity and Permeability (BCOP) test method is an organotypic model that provides short-term maintenance of normal physiological and biochemical function of the bovine corneain vitro. In this test method, damage by the test item is assessed by quantitative measurements of changes in corneal opacity and permeability.

The test method can correctly identify test items (both chemicals and mixtures) inducing serious eye damage as well as those not requiring classification for eye irritation or serious eye damage, as defined by the United Nations (UN) Globally Harmonized System of

Classification and Labelling of Items (GHS) and EU Classification, Labelling and Packaging (CLP) of chemicals (Regulation (EC) No 1272/2008), and it was therefore endorsed as scientifically valid for both purposes. Test items inducing serious eye damage are classified as UN GHS and EU CLP Category 1. Items not classified for eye irritation or serious eye damage are defined as those that do not meet the requirements for classification as UN GHS/EU CLP Category 1 or 2 (2A or 2B), i.e. they are referred to as UN GHS/EU CLP No Category.

Method

The undiluted test item was applied for 10 minutes followed by an incubation period of 120 minutes. Negative and positive control items were tested concurrently. The two endpoints, decreased light transmission through the cornea (opacity) and increased passage of sodium fluorescein dye through the cornea (permeability) were combined in an empirically derived formula to generate anIn VitroIrritancy Score (IVIS).  

IVIS	Classification
≤ 3	No category. Not requiring classification to UN GHS or EU CLP
> 3; ≤55	No prediction of eye irritation can be made
> 55	Category 1. UN GHS or EU CLP Causes serious eye damage

  

Results

The In Vitro irritancy scores are summarized as follows:

Treatment	In Vitrro Irritancy Score
Test Item	76.3
Negative Control	0.5
Positive Control	65.5

 

Conclusion

Category 1. UN GHS or EU CLP Causes serious eye damage.

Endpoint conclusion

Endpoint conclusion:

adverse effect observed (irreversible damage)