ethyl (3-benzoyl-2,4,6-trimethylbenzoyl)(phenyl)phosphinate

Skin irritation / corrosion

Administrative data

Endpoint:

skin corrosion: in vitro / ex vivo

Type of information:

experimental study

Adequacy of study:

key study

Study period:

01 August 2019 to 02 August 2019

Reliability:

1 (reliable without restriction)

Rationale for reliability incl. deficiencies:

guideline study

Cross-reference

Reason / purpose for cross-reference:

reference to same study

Reference

Endpoint:

skin irritation: in vitro / ex vivo

Type of information:

experimental study

Adequacy of study:

key study

Study period:

31 July 2019 to 02 August 2019

Reliability:

1 (reliable without restriction)

Rationale for reliability incl. deficiencies:

guideline study

Reason / purpose for cross-reference:

reference to same study

Qualifier:

according to guideline

Guideline:

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

Deviations:

no

GLP compliance:

yes (incl. QA statement)

Specific details on test material used for the study:

FORM AS APPLIED IN THE TEST
The test material was applied as supplied, no formulation was required.

Test system:

human skin model

Remarks:

EPISKIN™(SM)

Source species:

human

Cell type:

non-transformed keratinocytes

Justification for test system used:

The EPISKIN™(SM) model has been validated for corrosivity and irritation testing in an international validation study and its use is recommended by the relevant OECD guidelines for corrosivity and irritation testing (OECD No. 431 and OECD No. 439); therefore, it was considered to be suitable for this study.

Vehicle:

unchanged (no vehicle)

Remarks:

10 µL distilled water was applied to the epidermal surface in order to improve further contact between test material and epidermis

Details on test system:

RECONSTRUCTED HUMAN EPIDERMIS (RHE) TISSUE
- Model used: EPISKIN™(SM) Kit
- Source: SkinEthic, France
- Tissue lot number(s): 19-EKIN-031

TEST FOR DIRECT MTT REDUCTION
- 20 mg of test material was added to 2 mL MTT working solution and mixed. The mixture was incubated at 37 °C in an incubator with 5 % CO2, in a >95 % humidified atmosphere for 3 hours and any colour change was recorded. After three hours of incubation, yellow colour of the mixture was detected in the test tube indicating the test material did not react with MTT and therefore the use of additional controls was not necessary.

ASSESSMENT OF COLOUR INTERFERENCE WITH THE MTT ENDPOINT
- Prior to treatment, the test material was evaluated for its intrinsic colour or ability to become coloured in contact with water and/or isopropanol. The test material had colour, therefore, in addition to the normal procedure, two additional test material-treated living tissues were used for the non-specific OD evaluation. These tissues followed the same test mateiral application and all steps as for the other tissues, except for the MTT step: MTT incubation was replaced by incubation with fresh Assay Medium to mimic the amount of colour from the test material that may be present in the test disks. OD reading was conducted following the same conditions as for the other tissues.

MAIN TEST (performed under aseptic conditions)
PRE-INCUBATION
- 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 least 18 hours) at 37 °C in an incubator with 5 % CO2 in a > 95 % humidified atmosphere.

APPLICATION
- 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.
- An appropriate amount (10 µL) distilled water was applied to the epidermal surface in order to improve further contact between test material and epidermis and then 10 mg of test material were applied evenly to each of three test units and each additional control skin units. 10 mg of the test material covered properly the epidermal surface.
- 20 µL of negative control (PBS) or positive control (5 % (w/v) SDS solution) were added to each skin unit by using a suitable pipette. Chemicals were spread gently with the pipette tip in order to cover evenly all the epidermal surface if necessary (without damaging the epidermis).
- The plates with the treated epidermis units were incubated for the exposure time of 15 minutes at room temperature (23.3 - 25.1 °C)

REMOVAL OF TEST MATERIAL AND CONTROLS
- After 15 minutes incubation time the EPISKIN™ (SM) units were removed and rinsed thoroughly with PBS to remove as much as possible of any remaining material from the epidermal surface. The rest of the PBS was removed from the epidermal surface with a pipette (without touching the epidermis).
- After rinsing, the units were placed into the plate wells with fresh pre-warmed Maintenance Medium (2 mL/well) below them and then incubated for 42 hours (±1 hour) at 37 °C in an incubator with 5 % CO2, in a > 95 % humidified atmosphere.

MTT TEST
- MTT solution (2 mL of 0.3 mg/mL MTT working solution) was added to each well below the skin units. The lid was replaced and the plate incubated at 37 °C in an incubator with 5 % CO2 for 3 hours, protected from light, in a > 95 % humidified atmosphere.

FORMAZAN EXTRACTION
- At the end of incubation with MTT, a formazan extraction was undertaken. A disk of epidermis was cut from each skin unit (this procedure involved the maximum area of the disk) using the biopsy punch supplied as part of the kit. The epidermis was separated with the aid of forceps and both parts (epidermis and collagen matrix) were placed into a tube containing 500 µL acidified isopropanol (one tube corresponding to one well of the assay plate).
- The capped tubes were thoroughly mixed using a vortex mixer to achieve a good contact of all of the material and the acidified isopropanol, and then incubated overnight at room temperature protected from light with gentle agitation (~150 rpm) for formazan extraction.
- A blank sample containing 2 mL of acidified isopropanol was processed in parallel.

CELL VIABILITY MEASUREMENTS
- Following the formazan extraction, 2 × 200 µL sample from each tube were placed into the wells of a 96-well plate (labelled appropriately). The OD (optical density or absorbance) of the samples was measured using a plate reader at 570 nm. Plate reader linearity range: from 0.0 to 3.0 OD. The mean of 6 wells of acidified isopropanol solution (200 µL/well) was used as blank.

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

NUMBER OF REPLICATE TISSUES: 3
As the test material was coloured, two additional test material-treated living tissues were used for the non-specific OD evaluation.

DATA EVALUATION
The test material is identified as requiring classification and labelling according to UN GHS (Category 2 or Category 1) if the mean relative viability of three individual tissues after 15 minutes exposure to the test material and 42 hours post incubation is less or equal (=) to 50 % of the mean viability of the negative controls. In case the test material is found to be non-corrosive, and shows tissue viability after exposure and post-treatment incubation is less than or equal (=) to 50 %, the test material is considered to be irritant to skin in accordance with UN GHS Category 2. The test material may be considered to be non-irritant to skin in accordance with UN GHS (No Category), if the mean relative viability of three individual tissues after 15 minutes exposure to the test material and 42 hours post incubation is more than (¿) to 50 % of the mean viability of the negative controls.

Control samples:

yes, concurrent vehicle

yes, concurrent positive control

yes, concurrent MTT non-specific colour control

Amount/concentration applied:

TEST MATERIAL
- Amount(s) applied: 10 mg

NEGATIVE CONTROL
- Amount(s) applied: 20 µL

POSITIVE CONTROL
- Amount(s) applied: 20 µL

Duration of treatment / exposure:

15 minutes

Duration of post-treatment incubation (if applicable):

3 hours

Number of replicates:

3

Irritation / corrosion parameter:

% tissue viability

Run / experiment:

mean

Value:

87

Vehicle controls validity:

not applicable

Negative controls validity:

valid

Positive controls validity:

valid

Remarks on result:

no indication of irritation

Other effects / acceptance of results:

DIRECT MTT REDUCTION
- As no colour change (yellow colour) was observed after three hours incubation of the test material in MTT working solution, the test material did not interact with MTT. Therefore, additional controls and data calculations were not necessary. The false estimation of viability can be excluded.

ASSESSMENT OF COLOUR INTERFERENCE WITH THE MTT ENDPOINT
- Two additional test material-treated living tissues were used for the non-specific OD evaluation. The mean optical density (measured at 570 nm) of these tissues was determined as 0.011, Non Specific Colour % (NSCliving%) was calculated as 1.3 %. This is below the threshold of 5 %, therefore correction due to colouring potential was not necessary.

MAIN STUDY
- The mean OD value for the test material treated skin samples showed 87.0 % relative viability compared to the negative control.

QUALITY CRITERIA
- After receipt, the two indicators of the delivered kits were checked. Based on the observed colours, the epidermis units were in proper condition.
- The mean OD value of the blank samples (acidified isopropanol) was 0.047.
- The mean OD value of the three negative control tissues was in the recommended range (0.826) which satisfied the acceptability criterion of being 0.6 - 1.5. Standard deviation of the viability results for negative control samples was 4.3 %.
- The positive control treated tissues showed 8.0 % viability demonstrating the proper performance of the assay. The standard deviation of the viability results for positive control samples was 1.2 %.
- The standard deviation of viability values of the three test material-treated tissue samples in the MTT assay was 14.7 %.
- All these parameters were within acceptable limits and therefore the study was considered to be valid.

Optical Density (OD) and Calculated Relative Viability % of the Samples in the Irritation Test

Substance		Optical Density		Viability (%RV)
		Measured	Blank Corrected
Negative control Phosphate buffered saline	1	0.902	0.855	103.5
	2	0.884	0.836	101.3
	3	0.8834	0.786	95.2
	Mean	-	0.826	100.0
Positive control 5 % (w/v) SDS solution	1	0.103	0.056	6.7
	2	0.114	0.066	8.0
	3	0.124	0.076	9.2
	Mean	-	0.066	8.0
Test material	1	0.626	0.578	70.0
	2	0.827	0.779	94.4
	3	0.844	0.797	96.5
	Mean	-	0.718	87.0

Mean blank value was 0.047.

Optical density means the mean value of the duplicate wells for each sample (rounded to three decimal places).

SDS: Sodium dodecyl sulphate (5 % (w/v)).

Irritation Testing Historical Control: 20 µL Treatment Volume

	Mean Value (OD)	Standard Deviation (SD)	Minimum Value (OD)	Maximum Value (OD)	Number of Cases
Negative control
Year 2019, absorbance	0.870	0.099	0.617	1.061	80
Positive control
Year 2019, absorbance	0.048	0.031	0.010	0.160	80
Year 2019, viability %	5.6	3.5	1.1	16.3

Negative control: Phosphate buffered saline (PBS)

Positive control: Sodium dodecyl sulphate 5 % (w/v) (SDS)

SD: Standard deviation

OD: Optical density (absorbance)

All OD values (measured at 570) are background corrected values.

Interpretation of results:

GHS criteria not met

Remarks:

Not skin irritating

Conclusions:

Following exposure with the test material, the mean cell viability was 87.0 % compared to the negative control. This is above the threshold of 50 %, therefore the test material was considered as being non-irritant to skin.

Executive summary:

The skin irritation potential of the test material was investigated in a study which was conducted in accordance with the standardised guideline OECD 439, under GLP conditions.

The in vitro skin irritation test was performed in a reconstructed human epidermis model using EPISKIN™(SM), which is designed to predict and classify the irritation potential of chemicals by measuring its cytotoxic effect as reflected in the MTT [3-(4,5-Dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide, Thiazolyl blue] assay.

During the study, disks of EPISKIN™(SM) were treated with the test material and incubated for 15 minutes (in triplicate) at room temperature. Exposure of the test material was terminated by rinsing with Phosphate Buffered Saline (PBS). The epidermis units were then incubated at 37° C for 42 hours in an incubator with 5 % CO2, in a > 95 % humidified atmosphere. The viability of each disk was assessed by incubating the tissues for 3 hours with MTT solution at 37 °C in an incubator with 5 % CO2 protected from light, in a > 95 % humidified atmosphere. The precipitated formazan crystals were then extracted using acidified isopropanol and quantified spectrophotometrically.

PBS treated epidermis were used as negative control and 5 % (w/v) Sodium Dodecyl Sulphate (SDS) solution treated epidermis were used as positive control (three units/control). Two additional disks were used to provide in each case an estimate of colour contribution (NSCliving). For each treated tissue, the viability was expressed as a % relative to the negative control. For irritation, if the mean relative viability after 15 minutes exposure and 42 hours post incubation is less or equal (=) to 50 % of the negative control, the test mateiral is considered to be irritant to skin.

Following exposure with the test material, the mean cell viability was 87.0 % compared to the negative control. This is above the threshold of 50 %, therefore the test material was considered as being non-irritant to skin.

The experiment met the validity criteria, therefore the study was considered to be valid.

In conclusion, in this in vitro EPISKIN™ (SM) model test the test material was considered to be non-irritanting to the skin.

Data source

Reference

Reference Type:

study report

Title:

Unnamed

Year:

2020

Report date:

2020

Materials and methods

Test guideline

Qualifier:

according to guideline

Guideline:

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

Version / remarks:

2019

Deviations:

no

GLP compliance:

yes (incl. QA statement)

Test material

Test material information

Constituent 1

Reference substance name:

ethyl (3-benzoyl-2,4,6-trimethylbenzoyl)(phenyl)phosphinate

EC Number:

806-801-9

Cas Number:

1539267-56-5

Molecular formula:

C25H25O4P

IUPAC Name:

ethyl (3-benzoyl-2,4,6-trimethylbenzoyl)(phenyl)phosphinate

Test material form:

solid: particulate/powder

Details on test material:

- Appearance: White to off white.
- Storage conditions: Controlled room temperature (15 - 25 °C, =70 % relative humidity), protected from light.

Specific details on test material used for the study:

FORM AS APPLIED IN THE TEST
The test material was applied as supplied, no formulation was required.

In vitro test system

Test system:

human skin model

Remarks:

EPISKIN™(SM)

Source species:

human

Cell type:

non-transformed keratinocytes

Justification for test system used:

The EPISKIN™(SM) model has been validated for corrosivity and irritation testing in an international validation study and its use is recommended by the relevant OECD guidelines for corrosivity and irritation testing (OECD No. 431 and OECD No. 439); therefore, it was considered to be suitable for this study.

Vehicle:

unchanged (no vehicle)

Remarks:

100 µL of physiological saline was utilised to ensure good contact with the epidermis.

Details on test system:

RECONSTRUCTED HUMAN EPIDERMIS (RHE) TISSUE
- Model used: EPISKIN™(SM) Kit
- Source: SkinEthic, France
- Tissue lot number(s): 19-EKIN-031

TEST FOR DIRECT MTT REDUCTION
- 20 mg of test material was added to 2 mL MTT working solution and mixed. The mixture was incubated at 37 °C in an incubator with 5 % CO2, in a >95 % humidified atmosphere for 3 hours and any colour change was recorded. After three hours of incubation, yellow colour of the mixture was detected in the test tube indicating the test material did not react with MTT and therefore the use of additional controls was not necessary.

ASSESSMENT OF COLOUR INTERFERENCE WITH THE MTT ENDPOINT
- Prior to treatment, the test material was evaluated for its intrinsic colour or ability to become coloured in contact with water and/or isopropanol. The test material had colour, therefore, in addition to the normal procedure, two additional test material-treated living tissues were used for the non-specific OD evaluation. These tissues followed the same test mateiral application and all steps as for the other tissues, except for the MTT step: MTT incubation was replaced by incubation with fresh Assay Medium to mimic the amount of colour from the test material that may be present in the test disks. OD reading was conducted following the same conditions as for the other tissues.

MAIN TEST
PRE-INCUBATION
- 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 least 18 hours) at 37 °C in an incubator with 5 % CO2 in a > 95 % humidified atmosphere.

APPLICATION
- The Assay 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.
- 20 mg of test material was applied evenly to each of two test units and each additional control skin units and then 100 µL physiological saline was added to the test material to ensure good contact with the epidermis. 20 mg of the test material covered properly the epidermal surface.
- 50 µL of negative control (Physiological saline (0.9 % (w/v) NaCl solution)) or positive control (glacial acetic acid) were added to each skin unit by using a suitable pipette. Chemicals were spread gently with the pipette tip in order to cover evenly all the epidermal surface if necessary (without damaging the epidermis).
- The plates with the treated epidermis units were incubated for the exposure time of 4 hours at room temperature (24.2 - 24.8 °C).

REMOVAL OF TEST MATERIAL AND CONTROLS
- After 4 hours incubation time the EPISKIN™ (SM) units were removed and rinsed thoroughly with PBS to remove as much as possible of any remaining material from the epidermal surface. The rest of the PBS was removed from the epidermal surface with a pipette (without touching the epidermis).

MTT TEST
- MTT solution (2 mL of 0.3 mg/mL MTT working solution) was added to each well below the skin units. The lid was replaced and the plate incubated at 37 °C in an incubator with 5 % CO2 for 3 hours, protected from light, in a > 95 % humidified atmosphere.

FORMAZAN EXTRACTION
- At the end of incubation with MTT, a formazan extraction was undertaken. A disk of epidermis was cut from each skin unit (this procedure involved the maximum area of the disk) using the biopsy punch supplied as part of the kit. The epidermis was separated with the aid of forceps and both parts (epidermis and collagen matrix) were placed into a tube containing 500 µL acidified isopropanol (one tube corresponding to one well of the assay plate).
- The capped tubes were thoroughly mixed using a vortex mixer to achieve a good contact of all of the material and the acidified isopropanol, and then incubated overnight at room temperature protected from light with gentle agitation (~150 rpm) for formazan extraction.
- A blank sample containing 2 mL of acidified isopropanol was processed in parallel.

CELL VIABILITY MEASUREMENTS
- Following the formazan extraction, 2 × 200 µL sample from each tube were placed into the wells of a 96-well plate (labelled appropriately). The OD (optical density or absorbance) of the samples was measured using a plate reader at 570 nm. Plate reader linearity range: From 0.0 to 3.0 OD. The mean of 6 wells of acidified isopropanol solution (200 µL/well) was used as blank.

TEMPERATURE USED FOR TEST SYSTEM
- Temperature used during treatment / exposure: 37 °C
- Temperature of post-treatment incubation: 37 °C with MTT

NUMBER OF REPLICATE TISSUES: Two replicates per timepoint. Two negative controls and two positive controls were also run.

DATA EVALUATION
The cut-off value of 35% and classification method was validated in an international validation study of this kit (Fentem, 1998).

For 2 disks:
If both disks have mean viability of = 35 % = Non Corrosive
If both disks have mean viability of < 35 % = Corrosive (at the corresponding incubation period)

For more than 2 disks:
If the mean value is = 35 % and the variability is less than 50 % = Non Corrosive
If the mean value is < 35 % and the variability is less than 50 % = Corrosive

Control samples:

yes, concurrent vehicle

yes, concurrent positive control

yes, concurrent MTT non-specific colour control

Amount/concentration applied:

TEST MATERIAL
- Amount(s) applied: 20 mg

NEGATIVE CONTROL
- Amount(s) applied: 50 µL

POSITIVE CONTROL
- Amount(s) applied: 50 µL

Duration of treatment / exposure:

4 hours

Duration of post-treatment incubation (if applicable):

3 hours with MTT

Number of replicates:

2

Results and discussion

In vitro

Results

Irritation / corrosion parameter:

% tissue viability

Run / experiment:

mean

Value:

113.4

Vehicle controls validity:

not applicable

Negative controls validity:

valid

Positive controls validity:

valid

Other effects / acceptance of results:

DIRECT MTT REDUCTION
- As no colour change (yellow colour) was observed after three hours incubation of the test material in MTT working solution, the test material did not interact with MTT. Therefore, additional controls and data calculations were not necessary. The false estimation of viability can be excluded.

ASSESSMENT OF COLOUR INTERFERENCE WITH THE MTT ENDPOINT
- Two additional test material-treated living tissues were used for the non-specific OD evaluation. The mean optical density (measured at 570 nm) of tissues were 0.007, Non Specific Colour % was calculated as 1.0 %. No additional calculations were therefore deemed to be necessary.

MAIN STUDY
- The mean OD value for the test material treated skin samples showed 113.4% relative viability compared to the negative control.

QUALITY CRITERIA
- After receipt, the two indicators of the delivered kits were checked. Based on the observed colours, the epidermis units were in proper condition.
- The mean OD value of the blank samples (acidified isopropanol) was 0.047.
- The mean OD value of the two negative control tissues was in the recommended range (0.743 and 0.690, respectively) which satisfied the acceptability criterion of being 0.6 - 1.5.
- The positive control treated tissues showed 0.2 % relative viability when compared to the relevant negative control values, thus demonstrating the proper performance of the assay.
- The variability of the calculated viability values of the test material treated replicates were 14.3 %.
- The variability of the calculated viability values of the negative control treated replicates were 7.5 %.
- High viability results (>>100%) do regularly occur in cases where the test material causes metabolic stimulation in the exposed cells, so the study result is not considered to be invalid.

Any other information on results incl. tables

Optical Density (OD) and the Calculated Relative Viability % of the Samples in the Corrosivity Test

Substance		Optical Density		Viability (% RV)
		Measured	Blank Corrected
Negative control Physiological saline (0.9 % (w/v) NaCl)	1	0.791	0.743	103.7
	2	0.737	0.690	96.3
	Mean	-	0.717	10.0
Positive control Glacial acetic acid	1	0.051	0.003	0.5
	2	0.047	-0.001	-0.1
	Mean	-	0.001	0.2
Test material	1	0.918	0.871	121.5
	2	0.802	0.754	105.3
	Mean	-	0.813	113.4

Mean blank value was 0.047.

Optical density means the mean value of the duplicate wells for each sample (rounded to three decimal places).

 

Historical Control Data: Corrosivity Testing Period 4 Hours

	Negative Control (Physiological Saline Solution)	Positive Control (Glacial Acetic Acid)
Minimum optical density (OD)	0.590	0.000
Maximum optical density (OD)	1.516	0.051
Mean optical density (OD)	0.844	0.010
Standard Deviation (SD)	0.130	0.009
Number of cases	228	208

OD: Optical density (absorbance)

SD: Standard deviation

All optical density (OD) values are background corrected values (measured at 570 ± 30 nm).

 

Applicant's summary and conclusion

Interpretation of results:

other: Not skin corrosive

Conclusions:

Following exposure with the test material, the mean relative viability after 4 hours of treatment was 113.4 % compared to the appropriate negative control values of the performed experiments. The observed relative viability value was above the threshold of 35 %, therefore the test material was considered as being non-corrosive.

Executive summary:

The skin corrosion potential of the test material was investigated in a study which was conducted in accordance with the standardised guideline OECD 431, under GLP conditions.

The in vitro skin corrosivity study was performed in a reconstructed human epidermis model using EPISKIN™(SM), which is designed to predict and classify the corrosivity potential of chemicals by measuring its cytotoxic effect as reflected in the MTT [3-(4,5-Dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide, Thiazolyl blue] assay.

During the study, disks of EPISKIN™(SM) were treated with the test material and incubated for 4 hours (in duplicate) at room temperature. Exposure of the test material was terminated by rinsing with Phosphate Buffered Saline (PBS). The viability of each disk was assessed by incubating the tissues for 3 hours with MTT solution at 37 °C in an incubator with 5 % CO2 protected from light, in a > 95 % humidified atmosphere. The precipitated formazan crystals were then extracted using acidified isopropanol and quantified spectrophotometrically.

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

Following exposure with the test material, the mean relative viability after 4 hours of treatment was 113.4 % compared to the appropriate negative control values of the performed experiments. The observed relative viability value was above the threshold of 35 %, therefore the test material was considered to be 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, the test mateiral can be considered non-corrosive to the skin.