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Toxicological information

Skin irritation / corrosion

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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:
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. certificate)
Remarks:
By Hessisches Ministerium für Umwelt, Energie, Landwirtschaft und Verbraucherschutz

Test material

Reference
Name:
Unnamed
Type:
Constituent
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 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

Resultsopen allclose all
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)
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)
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 (absorbancetissue) / (mean absorbancenegative control)

*** relative absorbance per treatment group [rounded values]: 100 x (mean absorbancetest item / negative control) / (mean absorbancenegative 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.