ytterbia stabilised yttrium disilicate

Eye irritation

Administrative data

Endpoint:

eye irritation: in vitro / ex vivo

Type of information:

experimental study

Adequacy of study:

key study

Study period:

2017-11-16 to 2018-03-13

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

Qualifier:

according to guideline

Guideline:

OECD Guideline 492 (Reconstructed Human Cornea-like Epithelium (RhCE) Test Method for Identifying Chemicals Not Requiring Classification and Labelling for Eye Irritation or Serious Eye Damage)

Version / remarks:

28 July 2015

Deviations:

no

GLP compliance:

yes (incl. QA statement)

Test material

Test material information

Constituent 1

Reference substance name:

ytterbia stabilised yttrium disilicate

Molecular formula:

Yb2-xYxSi2O7

IUPAC Name:

ytterbia stabilised yttrium disilicate

Test material form:

solid: particulate/powder

Details on test material:

Name: ytterbium doped yttrium disilicate
Physical state: solid
Appearance: white powder
Further information on test material confidential.

Specific details on test material used for the study:

- No correction factor was applied in this study.
- Treatment of test material prior to testing: None, the test item was used in its original form.

Test animals / tissue source

Species:

human

Strain:

other: Reconstructed human cornea-like epithelium (tissues)

Details on test animals or tissues and environmental conditions:

- Source: MatTek, Bratislava, Slovak Republic
- Expiry date: The EpiOcular tissues were used within 72 hours of their production.
- Selection: At receipt, the tissues were inspected for obvious defects prior to use.
- Storage conditions: At receipt, the living EpiOcular tissues were stored on their day of arrival, at 37°C, 5% CO2, in a humidified incubator.
- Description of the cell system used, incl. certificate of authenticity and the mycoplasma status of the cell live: The EpiOcularTM model consists of an airlifted, living, multilayered ocular tissue construction (surface 0.60 cm²), reconstructed from normal (non-transformed) human-derived keratinocytes. This is a non-keratinised epithelium which models the cornea epithelium with progressively stratified, but not cornified cells. The 3D tissue consists of highly organised cell layers similar to that found in the cornea. The model features a normal ultra-structure and is functionally equivalent to human in vivo tissue.

Test system

Vehicle:

unchanged (no vehicle)

Controls:

yes, concurrent positive control

yes, concurrent negative control

Amount / concentration applied:

TEST MATERIAL
- Amount(s) applied (volume or weight with unit): 51 mg (± 1 mg)

NEGATIVE CONTROL:
- Amount(s) applied (volume or weight with unit): 50 μL

POSITIVE CONTROL:
- Amount(s) applied (volume or weight with unit): 50 μL

Duration of treatment / exposure:

6 hours (± 15 minutes)

Duration of post- treatment incubation (in vitro):

18 hours (± 15 minutes)

Number of animals or in vitro replicates:

2 per test group (test item, negative control and positive control)

Details on study design:

Details of the test procedure used:
- RhCE tissue construct used, including batch number: EpiOcular tissue, MatTek, Bratislava, Slovak Republic. Batch number documented in a certificate of analysis archived in the study files.
- Duration and temperature of exposure, post-exposure immersion and post-exposure incubation periods: Exposure for 6 hours at 37°C, then soaked in assay medium for 25 minutes at room temperature, blotted, and then incubated for 18 hours at 37°C.
- Indication of controls used for direct MTT-reducers and/or colouring test chemicals: As the test item was found in the preliminary test not to have any colouring potential or any direct MTT reducing properties, no additional controls were run during the main test.
- Wavelength used for quantifying MTT formazan: 570 nm
- Description of the method used to quantify MTT formazan: MTT formazan precipicates are extracted using isopropanol and quantified using spectrophotometry. Formazan extraction was performed overnight at +2 to 8°C and protected from light. The OD was measured at 570 nm using a plate reader.
- Acceptable variability between tissue replicates for positive and negative controls: Negative control acceptance criteria: mean cOD between 0.8 and 2.5. Positive control acceptance criteria: relative mean viability of the positive control is < 50% of the relative mean viability of the negative control.
- Acceptable variability between tissue replicates for the test chemical: Acceptable if the difference of viability between the two tissue replicates is < 20%.
- Data interpretation: A test substance is predicted as ocular irritant, if the mean relative tissue viability (%) of two tissues exposed to the test item is ≤ 60%.

Results and discussion

In vitro

Results

Irritation parameter:

other: relative viability in %

Run / experiment:

mean of duplicate tissues

Value:

106

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:

OTHER EFFECTS:
- Visible damage on test system: None
- Test for direct MTT reduction with the test item: The MTT solution containing the test item did not turn blue/purple when compared with the negative control. The test item was therefore considered not to have direct MTT reducing properties. As a result, no additional controls were performed on freeze-dead tissues in parallel to the main test.
- Test for the detection of the colouring potential of the test item: During this test, as both water and isopropanol solutions containing the test item did not change colour, the test item was found not to have a colouring potential. As a result, no additional controls were used in parallel to the main test.

ACCEPTANCE OF RESULTS:
- Acceptance criteria met for negative control: Yes. Mean cOD for the two replicate tissues was 1.636 and 1.662.
- Acceptance criteria met for positive control: Yes. 27 and 19% viability were observed for the two tissue replicates in the positive control, whereas 99 and 101% viability were observed for the two tissue replicates in the negative control. The relative mean viability in the positive control is hence < 50% of that in the negative control.
- Acceptable variability between replicate tissues treated with test item: Yes. A difference of only 2% was obtained between the replicate tissues.

Applicant's summary and conclusion

Interpretation of results:

GHS criteria not met

Conclusions:

The test substance was tested for its eye irritation potential in a Reconstructed Human Cornea-like Epithelium assay performed according to OECD guideline 492. Since the mean relative viability in the treated tissues after MTT reduction was 106%, which is higher than the cut-off level of 60%, the test results meet the criteria for a non-irritant response. Therefore, the test substance is not to be classified for eye irritation under the CLP Regulation.