Dibenzyl sulphoxide

Skin irritation / corrosion

Administrative data

Endpoint:

skin irritation: in vitro / ex vivo

Type of information:

experimental study

Adequacy of study:

key study

Study period:

8.12.2015 - 11.12.2015

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

Version / remarks:

Adopted: 28th July, 2015

Deviations:

no

Test guideline 2

Qualifier:

according to guideline

Guideline:

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

Version / remarks:

Commission Regulation (EC) No. 761/2009, 23rd July 2009

Deviations:

no

Test guideline 3

Qualifier:

according to guideline

Guideline:

other: MatTek Protocol for: INVITRO EpiDermTM SKIN IRRITATION TEST For use with MatTek Corporation’s Reconstructed Human Epidermal Model EpiDerm

Version / remarks:

Model EPI-200-SIT, Rev. 26/3/2012,1-37

Deviations:

no

GLP compliance:

yes (incl. QA statement)

Test material

Test material information

Constituent 1

Reference substance name:

Dibenzyl sulphoxide

EC Number:

210-668-7

EC Name:

Dibenzyl sulphoxide

Cas Number:

621-08-9

Molecular formula:

C14H14OS

IUPAC Name:

(phenylmethanesulfinylmethyl)benzene

Test material form:

solid: particulate/powder

Details on test material:

- State of aggregation:
- Particle size distribution:
- Mass median aerodynamic diameter (MMAD):
- Geometric standard deviation (GSD):
- Shape of particles:
- Surface area of particles:
- Crystal structure:
- Coating:
- Surface properties:
- Density:
- Moisture content:
- Residual solvent:
- Activation:
- Stabilisation:
- Other:

White solid powder
Storage: The test substance was stored in dry room in dark in closed container at the room temperature.
Content of water: 0.025 % w/w (volumetric Karl Fischer titration)

In vitro test system

Test system:

human skin model

Source species:

human

Cell type:

non-transformed keratinocytes

Cell source:

other: tissue for research puposes from accredited institutions

Source strain:

other: Keratinocyte strain 00267

Vehicle:

water

Details on test system:

RECONSTRUCTED HUMAN EPIDERMIS (RHE) TISSUE
tissues: the reconstructed human epidermal model EpiDerm (EPI-200 ver. 2.0, MatTek, Bratislava, SK); Lot No. 23306
Certificate of analysis 9.12.2015

TEMPERATURE USED FOR TEST SYSTEM
culture conditions 37±1°C, 5±1 % CO2, moistened tissue

REMOVAL OF TEST MATERIAL AND CONTROLS
- Volume and number of washing steps: thoroughly rinsed with PBS, blotted to remove the test substance
After exposition the test substance was removed, tissues were rinsed and post-incubated. Small amount (a few points) of the test substance remained in tissues after washing.

MTT DYE USED TO MEASURE TISSUE VIABILITY AFTER TREATMENT / EXPOSURE
- MTT concentration: 1 mg·mL-1
- Incubation time: 3 h
- Spectrophotometer: Libra S22 at 570 nm. Isopropyl alcohol serves as a blank.

FUNCTIONAL MODEL CONDITIONS WITH REFERENCE TO HISTORICAL DATA
Based on Certificate of Analysis the model passed all parametres for viability, barrier function, sterility.

NUMBER OF REPLICATE TISSUES: 3

NUMBER OF INDEPENDENT TEST SEQUENCES / EXPERIMENTS TO DERIVE FINAL PREDICTION:
1. Direct MTT reduction - functional check in tubes
2. MTT test

PREDICTION MODEL / DECISION CRITERIA
OECD Test Guideline No. 439 (1), par. 36:
- In case the test chemical is found to be non-corrosive (e.g., based on TG 430, 431 or 435), and shows tissue viability after exposure and post-treatment incubation is less than or equal (≤) to 50%, the test chemical is considered to be irritant to skin in accordance with UN GHS (3) Category 2.
- The test chemical may be considered as non-irritant to skin in accordance with UN GHS No Category if the tissue viability after exposure and post-treatment incubation is more than (>) 50%.

Control samples:

yes, concurrent negative control

yes, concurrent positive control

Amount/concentration applied:

25 mg of the test substance was placed directly atop the tissue previously moistened with 25 µL of PBS and it was layed such, that the test substance covered its entire surface.
NC: PBS (phosphate buffered saline), prepared 11/11/2015, exp. 11/05/2016 and 27/10/2015, exp. 27/04/2016
PC: 5 % SDS (sodium dodecyl sulphate), MatTek, Lot No. 020615TMH, exp. 06/02/2016

Duration of treatment / exposure:

1 hour

Duration of post-treatment incubation (if applicable):

42 hours

Number of replicates:

3

Results and discussion

In vitro

Results

Irritation / corrosion parameter:

% tissue viability

Run / experiment:

1

Value:

96.2

Negative controls validity:

valid

Positive controls validity:

valid

Other effects / acceptance of results:

All study acceptance criteria were fulfilled.
The mean OD570 of the NC tissue was 1.924 ±0.044 which meets the acceptance criteria of ≥ 0.8 and ≤ 2.8.
The mean viability of the PC tissues expressed as % of the negative control tissues is 3.5% which meets the acceptance criterion of ≤ 20 %.
The SD calculated from individual % tissue viabilities of the 3 identically treated replicates for the positive control, negative control and test substance was < 18 %.

Any other information on results incl. tables

MTT test

OD₅₇₀values obtained at the MTT test, their averages, standard deviations (%) and relative viabilities

Treatment	OD570			Mean	SD	%NC
PBS (NC)	1.984	1.910	1.879	1.924	0.044
viability (%NC)	103.1	99.3	97.6	100.0	2.3	100.0
480/15 (DBSO)	1.787	1.808	1.958	1.851	0.076
viability (%NC)	92.9	94.0	101.7	96.2	4.0	96.2
5% SDS (PC)	0.056	0.077	0.070	0.068	0.009
viability (%NC)	2.9	4.0	3.6	3.5	0.5	3.5

PBS - phosphate buffered saline

DBSO - Dibenzylsulfoxide

SDS - sodium dodecyl sulphate

Applicant's summary and conclusion

Interpretation of results:

GHS criteria not met

Conclusions:

Under the above-described experimental design, average viability of tissues treated by the test substance was 96.2 %, i.e.viability was > 50 %.
The effect of the test substance was negative in EpiDermTM model (the tissue was not damaged).
According to the classification criteria the test substance is considered to have no category in regard to skin irritation.

Executive summary:

Test substance, Dibenzylsulfoxide, was assayed for the in vitro skin irritation in human epidermal model EpiDermTM. The test was performed in compliance with european legislation (see Material and methods)

After pre-incubation of tissues, 25 mg of the test substance was placed directly atop to the previously moistened tissue so it covered all tissue surfaces. Length of exposition was 60 minutes. Three tissues were used for the test substance and for every control.

After removal of the test substance from tissues, tissues were post incubated for 42 hours due to leave of damage reparation. Three hours incubation with MTT and two hours extraction period with shaking followed then. Optical density (OD570) of isopropyl alcohol extracts was measured on a spectrophotometer. Relative cell viability was calculated for each tissue as % of the mean viability of the negative control tissues.

Under the above-described experimental design, average viability of tissues treated by the test substance was 96.2 %, i.e.viability was > 50 %.

The effect of the test substance was negative in EpiDermTM model (the tissue was not damaged).

According to the classification criteria the test substance is considered to have no category in regard to skin irritation.