Bis(2-hydroxyethyl) sulphone

Skin irritation / corrosion

Administrative data

Endpoint:

skin corrosion: in vitro / ex vivo

Type of information:

experimental study

Adequacy of study:

key study

Study period:

The study was conducted between 26 July 2016 and 29 July 2016

Reliability:

1 (reliable without restriction)

Rationale for reliability incl. deficiencies:

guideline study

Data source

Reference

Reference Type:

study report

Title:

Unnamed

Year:

2016

Report date:

2016

Materials and methods

Test guideline

Test guideline 1

Qualifier:

according to guideline

Guideline:

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

Test guideline 2

Qualifier:

according to guideline

Guideline:

other: Method B.40bis of Commission Regulation (EC) No 440/2008, of 30 May 2008, laying down test methods pursuant to Regulation (EC) No 1907/2006 of the European Parliament and of the Council on REACH.

GLP compliance:

yes (incl. QA statement)

Test material

Test material information

Constituent 1

Reference substance name:

Bis(2-hydroxyethyl) sulphone

EC Number:

219-948-3

EC Name:

Bis(2-hydroxyethyl) sulphone

Cas Number:

2580-77-0

Molecular formula:

C4H10O4S

IUPAC Name:

2-(2-hydroxyethanesulfonyl)ethan-1-ol

Test material form:

solid

Specific details on test material used for the study:

Identification: BHES
Physical state/Appearance: White solid block
Batch: 160226
Purity: 99.64%
Expiry Date: 01 March 2017
Storage Conditions: Room temperature in the dark

In vitro test system

Test system:

human skin model

Source species:

human

Cell type:

other: epithelial

Cell source:

other: derived from human skin

Source strain:

other: derived from human skin

Details on animal used as source of test system:

Details on EpiDerm™ Reconstructed Human Epidermis Model:
Supplier: MatTek
Date received: 28 July 2016
EpiDermTM Tissues (0.63cm2) lot number: 23347
Assay Medium lot number: 072116ZSA
Upon receipt of the EpidermTM tissues, the sealed 24 well plate was stored in a refrigerator until use.

Justification for test system used:

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.
This model incorporates several features, which make it advantageous in the study of potential dermal corrosivity. The target cells are epithelial, derived from human skin, and formed into a stratified, cornified epithelium. Test items are applied to the culture surface, at the air interface, so that undiluted and/or end use dilutions can be tested directly.

Vehicle:

unchanged (no vehicle)

Details on test system:

TEMPERATURE USED FOR TEST SYSTEM
- Temperature used during treatment / exposure: 37 °C, 5% CO2
- Temperature of post-treatment incubation (if applicable): 37 °C, 5% CO2

DYE BINDING METHOD
- Dye used in the dye-binding assay: MTT
- Spectrophotometer: Anthos 2001 microplate reader.
- Wavelength: 562nm (OD562)

NUMBER OF INDEPENDENT TESTING RUNS / EXPERIMENTS TO DERIVE FINAL PREDICTION: 1

PREDICTION MODEL / DECISION CRITERIA (choose relevant statement)
- The test substance is considered to be corrosive to skin if:
- the relative mean tissue viability (% of negative control) is < 50 after a 3 minute exposure
- the relative mean tissue viability (% of negative control) is ≥ 50 after a 3 minute exposure to the test substance AND < 15 after a 1 hour exposure to the test substance
- The test substance is considered to be non-corrosive to skin if:
- the relative mean tissue viability (% of negative control) is ≥ 50 after a 3 minute exposure to the test substance AND ≥ 15 after a 1 hour exposure to the test substance

Control samples:

yes, concurrent negative control

yes, concurrent positive control

Amount/concentration applied:

TEST MATERIAL
- Amount(s) applied (volume or weight with unit): 25 mg
- Concentration (if solution): 100% (as supplied)

NEGATIVE CONTROL (Sterile distilled water)
- Amount(s) applied (volume or weight): 50 µL of sterile distilled water


POSITIVE CONTROL (8.0N Potassium Hydroxide)
- Amount(s) applied (volume or weight): 50 µL
- Concentration (if solution): 8.0 N

Duration of treatment / exposure:

3 and 60 minutes

Duration of post-treatment incubation (if applicable):

3 hrs

Number of replicates:

2

Test animals

Species:

other: not applicable

Strain:

other: not applicable

Test system

Type of coverage:

other: substance was applied directly to the tissue

Preparation of test site:

other: The test item was applied topically to the corresponding tissues.

Vehicle:

unchanged (no vehicle)

Controls:

yes, concurrent positive control

yes, concurrent negative control

Amount / concentration applied:

See details above in Section 'in vitro test system'

Duration of treatment / exposure:

3 and 60 minutes

Number of animals:

A total of 12 tissues were used: Duplicate tissues were treated with: test substance, positive control or negative control for each exposure time

Details on 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 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.

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, each test item is checked for the ability to directly reduce MTT according to the following procedure:

50 µL of the melted 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 relative to the control, the test item was presumed to have reduced the MTT.

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 the melted test item was added to 300 µL of sterile water. The solution was incubated in the dark at 37 °C, 5% CO2 in air for 60 minutes. A visual assessment of the color was then made.


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.

MAIN TEST:
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. 25 mg of the test item and 50 µL of 8.0 N Potassium Hydroxide (positive control) were also applied to the corresponding tissues in turn. 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 562nm (OD562) of each well was measured using the Anthos 2001 microplate reader.

Results and discussion

In vitro

Results

Results 1

Irritation / corrosion parameter:

other: relative mean viability %

Run / experiment:

3 minute exposure

Value:

95.6

Vehicle controls validity:

not applicable

Negative controls validity:

valid

Positive controls validity:

valid

Remarks on result:

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

Results 2

Irritation / corrosion parameter:

other: relative mean viability %

Run / experiment:

60 minute exposure

Value:

93.2

Vehicle controls validity:

not applicable

Negative controls validity:

valid

Positive controls validity:

valid

Remarks on result:

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

Other effects / acceptance of results:

No other effects were observed

Any other information on results incl. tables

Direct MTT Reduction

The MTT solution containing the test item did not turn blue. This was taken to indicate the test item did not reduce MTT.

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.

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

Exposure Period	Percentage Viability
	Negative Control	Positive Control	Test Item
3 minute	100*	5.6	95.6
60 minute	100*	5.3	93.2

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

Quality Criteria

The mean OD₅₆₂for the negative control treated tissues was 1.801 for the 3‑Minute exposure period and 1.775 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 5.3% 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.

Mean OD₅₆₂Values and Viabilities for the Negative Control Item, Positive Control Item and Test Item are presented in the table below:

Tissue	Exposure Period	MeanOD562of individual tissues	Mean OD562of duplicate tissues	Standard Deviation	Coefficient of Variation (%)	Relative Mean Viability (%)
Negative Control	3 Minutes	1.877	1.801	0.107	6.0	100*
		1.725
	60 Minutes	1.822	1.775	0.066	3.7
		1.728
Positive Control	3 Minutes	0.110	0.100	0.014	Na	5.6
		0.090
	60 Minutes	0.110	0.094	0.023	Na	5.3
		0.077
Test Item	3 Minutes	1.799	1.723	0.108	6.3	95.6
		1.646
	60 Minutes	1.553	1.655	0.144	8.7	93.2
		1.756

OD = Optical density

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

Applicant's summary and conclusion

Interpretation of results:

GHS criteria not met

Conclusions:

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

Executive summary:

Introduction

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. 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 562 nm (OD₅₆₂).

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*	5.6	95.6
60 minute	100*	5.3	93.2

*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.