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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:
migrated information: read-across from supporting substance (structural analogue or surrogate)
Adequacy of study:
key study
Reliability:
2 (reliable with restrictions)
Rationale for reliability incl. deficiencies:
other: Read-across from GLP-compliant guideline study performed with similar substance.

Data source

Reference
Reference Type:
study report
Title:
Unnamed
Year:
2014

Materials and methods

Test guidelineopen allclose all
Qualifier:
according to
Guideline:
OECD Guideline 439 (In Vitro Skin Irritation: Reconstructed Human Epidermis Test Method)
Version / remarks:
Reconstructed Human Epidermis Test Method of 2013
Deviations:
no
Qualifier:
according to
Guideline:
other: L’Oreal. In Vitro Skin Irritation Test: Human Epidermis Model EPISKIN, EPISKIN Skin Irritation Test 15min - 42 hours, Standard Operating Procedure: February 2009 Version 1.8.
Deviations:
no
GLP compliance:
yes (incl. certificate)

Test material

Reference
Name:
Unnamed
Type:
Constituent
Test material form:
solid: particulate/powder
Remarks:
migrated information: powder

Test system

Vehicle:
unchanged (no vehicle)
Amount / concentration applied:
Types of Treatment in the Main Test
- Negative control: Dulbecco's Phosphate Buffered Saline (DPBS), dose volume 10 µl/tissue sample
- Test Substance: WS405777, dose 10 mg/tissue sample after wetting with 5 µl purified water
- Positive control: 5% Sodium Dodecyl Sulphate (SDS) in purified water, dose volume 10 µl/tissue sample
Duration of treatment / exposure:
15 ± 0.5 minutes with the test substance, negative or positive control at room temperature, followed by thorough rinsing of each epidermis unit with Dulbecco's phosphate buffered saline
Details on study design:
Test System
EPISKIN human epidermis skin constructs consisting of normal, human-derived epidermal keratinocytes and forming a multilayered, highly differentiated model of the human epidermis with a functional multilayered stratum corneum (matrix: collagen type 1 coated with type IV collagen).

Principle of the Test – Main Test
Irritant substances are sufficiently cytotoxic to cause cell deaths in the cell layers. Therefore, cell viability of the multilayers was determined by measurement of mitochondrial dehydrogenase activity assessed by reduction of MTT (3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide) to a soluble, coloured, formazan salt. The degree of formazan salt formation (positively correlated with the degree of cell viability) was measured photometrically (i.e. determination of the optical density of formazan extracts from tissue at 540 nm).

Depending on the percentage of tissue viability attained (compared to negative control viability) a test substance is classified as skin irritating or not skin irritating.

Pre-Tests – Checking for Interference of the Test Substance with the Assay
It was demonstrated, that the test material WS405777 itself did not interact with MTT. Also the test substance WS405777 did not show any potential for colouring water.

Main Test
Each treatment group (test substance, negative/positive controls) comprised 3 live (viable) tissue samples placed into wells of 12 well plates.

Incubation of these tissues before treatment in maintenance medium: ≥ 24 h at 37°C, 5% CO2 in air, in humidified atmosphere , in wells
each containing 2 mL fresh pre-warmed maintenance medium.
Test material administration: Spreading of thin even layer over the epidermal surface.
Termination of 15 ± 0.5 minute exposure period: Removal of residual test material or positive control substance by thorough
rinsing of each epidermis unit with Dulbecco's PBS;
removal of remaining PBS by blotting on absorbent paper.
Posttreatment incubation (all tissue samples) : 42 ± 1 h at 37°C , 5% CO2 in humidified atmosphere, in wells each containing
2 mL fresh pre-warmed maintenance medium
Then MTT incubation: 3 hours (± 5 minutes) at 37°C , 5% CO2 in humidified atmosphere, in wells each containing 2 mL of 0.3 mg/mL MTT.
Formazan extraction (all tissue samples) : Further processing of tissue samples & formazan extraction by vortexing in
acidic isopropanol, 500 µL/sample. The vortexed samples were stored at 2-8°C
protected from light for 48 - 70 hours.
Qantitative determination of optical density: At 540 nm with acidified isopropanol (0.04 N HCl final concentration,
6 x 200 µL) as blanks.

Results and discussion

In vitro

Resultsopen allclose all
Irritation / corrosion parameter:
other:
Value:
100
Remarks on result:
other:
Remarks:
Basis: mean. Time point: Following 15 ± 0.5 minutes control exposure to DPBS, 42 ± 1 h incubation in fresh maintenance medium, 3 h incubation in MTT solution and 48 - 70 h formazan extraction. Max. score: 100.0. Reversibility: other: not applicable to the EPISKIN skin irritation assay. Remarks: Mean OD of replicate blanks has been accounted for by subtraction. (migrated information)
Irritation / corrosion parameter:
other:
Value:
98.7
Remarks on result:
other:
Remarks:
Basis: mean. Time point: Following 15 ± 0.5 minutes exposure to WS405777, 42 ± 1 h incubation in fresh maintenance medium, 3 h incubation in MTT solution and 48 - 70 h formazan extraction. Reversibility: other: not applicable to the EPISKIN skin irritation assay. Remarks: Mean OD of replicate blanks has been accounted for by subtraction. . (migrated information)
Irritation / corrosion parameter:
other:
Value:
18.1
Remarks on result:
other:
Remarks:
Basis: mean. Time point: Following 15 ± 0.5 minutes exposure to 5% SDS, 42 ± 1 h incubation in fresh maintenance medium, 3 h incubation in MTT solution and 48 - 70 h formazan extraction. Reversibility: other: not applicable to the EPISKIN skin irritation assay. Remarks: Mean OD of replicate blanks has been accounted for by subtraction.. (migrated information)

In vivo

Irritant / corrosive response data:
See Table 1

Any other information on results incl. tables

As outlined in the „Validity Assessment Report“ for the read-across approach (see IUCLID Section 13) read-across from testing data obtained with the UVCB substance WS405777 is considered appropriate for the safety evaluation as well as classification and labelling of the mono-constituent substance WS406663 based on the close chemical similarity between the two substances.

Applicant's summary and conclusion

Interpretation of results:
not irritating
Remarks:
Migrated information Criteria used for interpretation of results: EU
Executive summary:

As outlined in the „Validity Assessment Report“ for the read-across approach (see IUCLID Section 13) read-across from testing data obtained with the UVCB substance WS405777 is considered appropriate for the safety evaluation as well as classification and labelling of the mono-constituent substance WS406663 based on the close chemical similarity between the two substances.

WS406663 does not necessitate any classification regarding skin irritation.