Sodium 3-[[(dimethylamino)thioxomethyl]thio]propanesulphonate

Skin irritation / corrosion

Administrative data

Endpoint:

skin irritation: in vitro / ex vivo

Type of information:

experimental study

Adequacy of study:

key study

Study period:

2016-01-18 - 2016-02-16 (experimental phase)

Reliability:

1 (reliable without restriction)

Rationale for reliability incl. deficiencies:

other: Well-documented GLP OECD 439 guideline study on the registered substance itself without deviations

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:

OECD Guideline for the Testing of Chemicals, Version 439, 28. July 2015, “In Vitro Skin Irritation: Reconstructed Human Epidermis (RhE) Test Method”

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:

• EU method B.46 BIS. “IN VITRO SKIN IRRITATION: RECONSTRUCTED HUMAN EPIDERMIS MODEL TEST”, dated 24. Aug. 2009

Deviations:

no

GLP compliance:

yes (incl. QA statement)

Remarks:

Landesamt für Umwelt, Wasserwirtschaft und Gewerbeaufsicht, Kaiser-Friedrich-Straße 7, 55116 Mainz, Germany

Test material

Test material information

Constituent 1

Reference substance name:

Sodium 3-[[(dimethylamino)thioxomethyl]thio]propanesulphonate

EC Number:

242-644-7

EC Name:

Sodium 3-[[(dimethylamino)thioxomethyl]thio]propanesulphonate

Cas Number:

18880-36-9

Molecular formula:

C6H13NO3S3.Na

IUPAC Name:

sodium 3-[(dimethylcarbamothioyl)sulfanyl]propane-1-sulfonate

Test material form:

solid: particulate/powder

Remarks:

migrated information: powder

Details on test material:

- Name of test material (as cited in study report): sodium 3-[[(dimethylamino)thioxomethyl]thio]propanesulphonate, DPS
- Substance type: pure substance
- Storage condition of test material: Room Temperature (20 ± 5°C)
- Other: Homogeneity: homogeneous

Test animals

Species:

human

Strain:

other: human-derived epidermal keratinocytes which have been cultured to form a multi-layered, highly differentiated model of the human epidermis

Details on test animals or test system and environmental conditions:

Test System

Specification
Commercially available EpiDermTM-Kit.
The EpiDermTM tissue consists of human-derived epidermal keratinocytes which have been cultured to form a multi-layered, highly differentiated model of the human epidermis. It consists of organized basal, spinous and granular layers, and a multi-layered stratum corneum containing intercellular lamellar lipid layers arranged in patterns analogous to those found in vivo. The EpiDermTM tissues are cultured on specially prepared cell cultures inserts.

Origin
EpiDermTM tissues were procured from MatTek In Vitro Life Science Laboratories, Brati-slava.
Designation of the kit: EPI-200-SIT
Day of delivery: 09. Feb. 2016
Batch no.: 23312

Test system

Type of coverage:

other: not applicable

Preparation of test site:

other: not applicable

Vehicle:

unchanged (no vehicle)

Controls:

other: DPBS-buffer was used as negative control, 5 % SDS solution was used as positive control.

Amount / concentration applied:

TEST MATERIAL
- Amount(s) applied (volume or weight with unit): 24.7, 25.4, and 25.5 mg/plate

Duration of treatment / exposure:

60 min

Observation period:

42.75h postincubation, 3h MTT incubation

Number of animals:

Each 1 plate with 3 tissues for negative and positive control and test item

Details on study design:

REMOVAL OF TEST SUBSTANCE
- Washing (if done): Rinsing with DPBS buffer
- Time after start of exposure: 60 min

SCORING SYSTEM: Formazan production as described in OECD Guideline 439

Results and discussion

In vitro

Results

Results 1

Irritation / corrosion parameter:

other: other: Formazan production

Value:

103.1

Remarks on result:

other:

Remarks:

Basis: mean. Time point: 1 h incubation, 42h postincubation. Reversibility: other: not applicable. Remarks: Test item; above the threshold for skin irritation (50%).. (migrated information)

Results 2

Irritation / corrosion parameter:

other: other: Formazan production

Value:

3.7

Remarks on result:

other:

Remarks:

Basis: mean. Time point: 1 h incubation, 42h postincubation. Reversibility: other: not applicable. Remarks: Positive control; below the threshold for skin irritation (50%).. (migrated information)

In vivo

Irritant / corrosive response data:

The relative absorbance values were increased to 101.3% after the treatment. This value is above the threshold for skin irritation (50%). Therefore, the test item is considered as not irritant to skin.

Any other information on results incl. tables

Findings and Results

 

Measured Values

As blank, the optical density of isopropanol was measured in eight wells of the 96-well-plate. The measured values and their mean are given in the following table:

 

Table Absorbance values blank isopropanol (OD at 570 nm)

Replicate	1	2	3	4	5	6	7	8	Mean
Absorbance	0.040	0.039	0.039	0.039	0.038	0.039	0.044	0.038	0.040

 

The absorbance values of negative control, test item and positive control are given in the following table:

 

Table Absorbance Values negative control, test item and positive control (OD at 570 nm)

Designation	Measurement	Negative Control	Test item	Positive Control
Tissue 1	1	1.837	1.729	0.103
	2	1.793	1.835	0.096
Tissue 2	1	1.645	1.615	0.094
	2	1.585	1.580	0.092
Tissue 3	1	1.510	1.609	0.105
	2	1.473	1.600	0.104

 

From the measured absorbances, the mean of each tissue was calculated, subtracting the mean absorbance of isopropanol as given above. Mean and relative standard deviation (comparison of the three tissues) were also calculated.

 

Table Mean Absorbance Values

Designation	Negative Control	Test item	Positive Control
Mean – blank (tissue 1)	1.775	1.742	0.060
Mean – blank (tissue 2)	1.575	1.558	0.053
Mean – blank (tissue 3)	1.452	1.565	0.065
Mean of the three tissues	1.601	1.622	0.059

 

 

Comparison of Formazan Production

For the test item and the positive control, the following percentage values of formazan production were calculated in comparison to the negative control:

 

Table % Formazan Production

Designation	Test item	Positive Control
% Formazan production (tissue 1)	108.8%	3.7%
% Formazan production (tissue 2)	97.3%	3.3%
% Formazan production (tissue 3)	97.8%	4.1%
% Formazan production (mean)	101.3%	3.7%
± SD of mean Formazan production (%)	6.5%	0.4%

 

 

Assessment and Validity

 

Skin Irritation Potential of the Test Item

The relative absorbance values were increased to 101.3% after the treatment. This value is above the threshold for skin irritation (50%). Therefore, the test item is considered as not irritant to skin.

 

Validity and Acceptability

Validity criteria and results are stated in the following table:

 

Table Validity

Criterion	Demanded	Found
OD of negative control	≥ 0.8 and ≤ 2.8	1.6
% Formazan production of positive control SDS	£20% of negative control	3.7%
SD of mean viability of the tissue replicates (%)	≤ 18	10.2% (negative control) 0.4%  (positive control) 6.5%  (test item)

 

All validity criteria were met.

Values for negative control and for positive control were within the range of historical data of the test facility.

Therefore, the experiment is considered valid.

Applicant's summary and conclusion

Interpretation of results:

GHS criteria not met

Conclusions:

Testing was performed via a GLP OECD 439 guideline study on the registered substance itself. The present in vitro method is recommended in a tiered testing approach, it was used as the first tier in a bottom-up approach, which may serve as a standalone test in case no indication of irritation was observed.
The validity criteria are met, making the results sufficiently reliable to assess the irritating potential of the test item to the skin. The present in vitro method allows the identification of irritating chemical substances and mixtures.
The relative absorbance values were increased to 101.3% after the treatment. This value is above the threshold for skin irritation (50%). Therefore, the test item is considered as not irritant to skin.

Executive summary:

In an OECD 439 (in vitro skin irritation) study under GLP, two experiments were performed.

The first experiment was not valid, because the variation between the replicates of the negative control was too high. Therefore, the experiment was repeated and the results of the invalid experiment are not reported, but kept in the GLP archive of the test facility. The repetition of the experiment was valid.

 

Three tissues of the human skin model EpiDermTM were treated with sodium 3-[[(dimethylamino)thioxomethyl]thio]propanesulphonate, DPS for 60 min.

The test item was applied directly to each tissue and spread to match the tissue size (0.63 cm²; as indicated by supplier).

DPBS-buffer was used as negative control, 5 % SDS solution was used as positive control.

After treatment with the negative control, the absorbance values were within the required acceptability criterion of 0.8 ≤ mean OD ≤ 2.8, OD was 1.6. The positive control showed clear irritating effects. Relative absorbance was reduced to 3.7% (required: < 20%).

Variation within tissues was acceptable (required: ≤ 18 %).

 

After the treatment with the test item, the relative absorbance values were increased to 101.3%. This value is well above the threshold for irritation potential (50%).

 

Therefore, sodium 3-[[(dimethylamino)thioxomethyl]thio]propanesulphonate, DPS is considered as not skin irritant in the Human Skin Model Test.