3-methylthiazolidine-2-thione

Skin irritation / corrosion

Administrative data

Endpoint:

skin irritation: in vitro / ex vivo

Type of information:

experimental study

Adequacy of study:

key study

Reliability:

1 (reliable without restriction)

Rationale for reliability incl. deficiencies:

other: GLP guideline study on the registered substance itself.

Data source

Reference

Reference Type:

study report

Title:

Unnamed

Year:

2015

Report date:

2015

Materials and methods

Test guideline

Qualifier:

according to guideline

Guideline:

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

Version / remarks:

In Vitro EpiDermTM Skin Irritation Test (EPI-200-SIT) for use with MatTek Corporation’s Reconstructed Human Epidermal Model EpiDerm (EPI-200), Rev. 3/26/2012

Deviations:

no

GLP compliance:

yes (incl. QA statement)

Remarks:

By Hessisches Ministerium für Umwelt, Energie, Landwirtschaft und Verbraucherschutz

Test material

Test material information

Constituent 1

Reference substance name:

3-methylthiazolidine-2-thione

EC Number:

217-614-1

EC Name:

3-methylthiazolidine-2-thione

Cas Number:

1908-87-8

Molecular formula:

C4H7NS2

IUPAC Name:

3-methyl-1,3-thiazolidine-2-thione

Test material form:

solid: pellets

Details on test material:

- Name of test material (as cited in study report): 3-Methyl-thiazolidin-2-thion
- Substance type: pure substance
- Storage condition of test material: at room temperature

Test animals

Species:

other: human-derived keratinocytes

Strain:

other: not applicable

Details on test animals or test system and environmental conditions:

not applicable

Test system

Type of coverage:

other: not applicable

Preparation of test site:

other: not applicable

Vehicle:

other: Dulbecco's Phosphate Buffered Saline (DPBS)

Controls:

yes, concurrent vehicle

Amount / concentration applied:

TEST MATERIAL
- Amount(s) applied (volume or weight with unit): 25 mg ≙ 39 mg/cm²

VEHICLE
- Amount(s) applied (volume or weight with unit): wetted with 50µl DPBS

Duration of treatment / exposure:

60 min

Observation period:

post incubation for 41.5 h in total

Number of animals:

not applicable, 3 replicates / treatment group

Details on study design:

TEST SITE
- % coverage: 100%

REMOVAL OF TEST SUBSTANCE
- Washing (if done): Yes, tissues were gently rinsed with DPBS at least 15 times.
- Time after start of exposure: 60 min

Results and discussion

In vitro

Results

Results 1

Irritation / corrosion parameter:

other: other: relative mean absorbance, MTT assay

Value:

88.9

Remarks on result:

other:

Remarks:

Basis: mean. Time point: 60min + 41.5h. Reversibility: other: not applicable. Remarks: test item. (migrated information)

Results 2

Irritation / corrosion parameter:

other: other: relative mean absorbance, MTT assay

Value:

100

Remarks on result:

other:

Remarks:

Basis: mean. Time point: 60min + 41.5h. Reversibility: other: not applicable. Remarks: negative control. (migrated information)

Results 3

Irritation / corrosion parameter:

other: other: relative mean absorbance, MTT assay

Value:

2.9

Remarks on result:

other:

Remarks:

Basis: mean. Time point: 60min + 41.5h. Reversibility: other: not applicable. Remarks: positive control. (migrated information)

Other effects / acceptance of results:

The mean relative absorbance value of the test item, corresponding to the cell viability, decreased to 88.9% (threshold for irritancy: ≤ 50%), consequently the test item was not irritant to skin.

Any other information on results incl. tables

Results after treatment with 3-Methyl-thiazolidin-2-thion and the controls:

 

Dose Group	Treat-ment Interval	Absor-bance 570 nm Tissue 1*	Absor-bance 570 nm Tissue 2*	Absor-bance 570 nm Tissue 3*	Mean Absor-bance of 3 Tissues	Rel. Absor-bance [%] Tissue 1, 2 + 3**	Relative Standard Deviation [%]	Mean Rel. Absorbance [% of Negative Control]***
Negative Control	60 min	1.999	1.903	1.976	1.959	102.0 97.1 100.8	2.5	100.0
Positive Control	60 min	0.047	0.063	0.061	0.057	2.4 3.2 3.1	15.0	2.9
Test Item	60 min	1.927	1.541	1.757	1.742	98.4 78.7 89.7	11.1	88.9

 

* Mean of three replicate wells after blank correction

** relative absorbance per tissue [rounded values]: 100 x (absorbance_tissue) / (mean absorbance_{negative control})

*** relative absorbance per treatment group [rounded values]: 100 x (mean absorbance_{test item / negative control}) / (mean absorbance_{negative control})

 

The optical pre-experiment (colour interference pre-experiment) to investigate the test item’s colour change potential in water did not led to a change in colour.

Optical evaluation of the MTT-reducing capacity of the test item after 1 hour incubation with MTT-reagent did not show blue colour.

The mean relative absorbance value of the test item, corresponding to the cell viability, decreased to 88.9% (threshold for irritancy: ≤ 50%), consequently the test item was not irritant to skin.

Applicant's summary and conclusion

Interpretation of results:

GHS criteria not met

Remarks:

UN GHS and EU CLP regulation

Conclusions:

Testing was performed via a GLP guideline study on the registered substance itself. The present in vitro method is recommended in a tiered testing approach and the validity criteria are met, making the results sufficiently reliable to assess the skin irritating potential of 3-Methyl-thiazolidin-2-thion. In conclusion, it can be stated that in this study and under the experimental conditions reported, 3-Methyl-thiazolidin-2-thion is not irritant to skin according to UN GHS and EU CLP regulation. The present result suffices to conclude that no hazard arises from 3-Methyl-thiazolidin-2-thion, no in vivo study is required.

Executive summary:

This in vitro study was performed to assess the irritation potential of 3-Methyl-thiazolidin-2-thion by means of the Human Skin Model Test.

The test item did not reduce MTT (test for direct MTT reduction), and it did not change colour when mixed with deionised water (test for colour interference). Also its intrinsic colour was not intensive. Consequently, additional tests with freeze-killed or viable tissues were not necessary.

Each three tissues of the human skin model EpiDerm™ were treated with the test item, the negative or the positive control for 60 minutes.

Approximately 25 mg of the test item were applied to each tissue, wetted with 50 μL of DPBS, and spread to match the surface of the tissue.

30 μL of either the negative control (DPBS) or the positive control (5% SLS) were applied to each tissue.

After treatment with the negative control the absorbance values were well in the required range of the acceptability criterion of mean OD ≥ 0.8 and ≤ 2.8 for the 60 minutes treatment interval, thus assuring the quality of the tissues.

Treatment with the positive control induced a sufficient decrease in the relative absorbance as compared to the negative control for the 60 minutes treatment interval, and thus assuring the validity of the test system.

After treatment with the test item 3-Methyl-thiazolidin-2-thion the mean relative absorbance value decreased irrelevantly to 88.9% compared to the relative absorbance value of the negative control. This value is above the threshold for irritancy of ≤ 50%. Therefore, the test item is not considered to possess an irritant potential.

In conclusion, it can be stated that in this study and under the experimental conditions reported, 3-Methyl-thiazolidin-2-thion is not irritant to skin.