CTO

Skin irritation / corrosion

Administrative data

Endpoint:

skin irritation: in vitro / ex vivo

Type of information:

experimental study

Adequacy of study:

key study

Study period:

01 to 15 December 2017

Reliability:

1 (reliable without restriction)

Rationale for reliability incl. deficiencies:

guideline study

Data source

Reference

Reference Type:

study report

Title:

Unnamed

Year:

2018

Report date:

2018

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:

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:

2012

Deviations:

no

GLP compliance:

yes (incl. QA statement)

Test material

Test material information

1

Reference substance name:

Cesium tungstate (Cs0.33WO3)

Cas Number:

189619-69-0

Molecular formula:

Cs0.33WO3

IUPAC Name:

Cesium tungstate (Cs0.33WO3)

Test material form:

solid: particulate/powder

Specific details on test material used for the study:

SOURCE OF TEST MATERIAL
- Source and lot/batch No. of test material: B0345
- Expiration date of the lot/batch: 08. Feb. 2022
- Purity: >99%
- Appearance: dark blue powder

In vitro test system

Test system:

human skin model

Source species:

human

Cell type:

non-transformed keratinocytes

Details on animal used as source of test system:

The EpiDerm 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 representing main lipid classes analogous to those found in vivo. The EpiDerm tissues are cultured on specially prepared cell culture inserts.

Vehicle:

unchanged (no vehicle)

Details on test system:

RECONSTRUCTED HUMAN EPIDERMIS (RHE) TISSUE
- Model used: commercially available EpiDerm™ -Kit, procured by MatTek. Designation of kit: EPI-200-SIT
- Tissue batch number(s): 25864
- Delivery date: 12. December 2017

TEMPERATURE USED FOR TEST SYSTEM
- Temperature used during treatment / exposure: 37 ± 1°C
- Temperature of post-treatment incubation: 37 ± 1°C

Control samples:

yes, concurrent negative control

yes, concurrent positive control

Amount/concentration applied:

TEST MATERIAL
- Amount(s) applied: Tissue 1: 24.7 mg; Tissue 2: 25.1 mg; Tissue 3: 25.6 mg
- test item was applied directly to each tissue and spread to match the tissue size (0.63 cm²; as indicated by the supplier).

NEGATIVE CONTROL
- Amount(s) applied: 30 µL per tissue

POSITIVE CONTROL
- Amount(s) applied: 30 µL per tissue
- Concentration: solution in demineralised water containing 5% Sodium dodecyl sulphate (SDS)

Duration of treatment / exposure:

60 minutes

Duration of post-treatment incubation (if applicable):

19 hours and 5 minutes

Number of replicates:

One plate (3 tissues) each for the test item, for negative control, and for positive control

Results and discussion

In vitro

Results

Irritation / corrosion parameter:

% tissue viability

Run / experiment:

One valid experiment was performed

Value:

113.2

Vehicle controls validity:

not applicable

Negative controls validity:

valid

Positive controls validity:

valid

Remarks on result:

no indication of irritation

Other effects / acceptance of results:

The following validity criteria and results are provided:

Criterion: OD of negative control
Demanded: ≥ 0.8 and ≤ 2.8
Result: 1.5

Criterion: % tissue viability of positive control SDS
Demanded: ≤ 20% of negative control
Result: 2.2%

Criterion: SD of mean viability of the tissue replicates (%)
Demanded: ≤ 18%
Results: 1.6% (negative control), 0.2% (positive control), 2.3% (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.

Applicant's summary and conclusion

Interpretation of results:

GHS criteria not met

Conclusions:

The test item, Cesium Tungsten Oxide, is considered as non-irritant to skin. After the treatment, the mean value of relative tissue viability was increased to 113.2%. This value is above the threshold for skin irritation (50%). All validity criteria were met.