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Toxicological information

Eye irritation

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Administrative data

Endpoint:
eye irritation: in vitro / ex vivo
Type of information:
experimental study
Adequacy of study:
key study
Study period:
22-23 February 2017
Reliability:
1 (reliable without restriction)
Rationale for reliability incl. deficiencies:
guideline study
Remarks:
GLP study performed according to OECD Guideline 492 without any deviation

Data source

Reference
Reference Type:
study report
Title:
Unnamed
Year:
2017
Report Date:
2017

Materials and methods

Test guideline
Qualifier:
according to
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:
adopted 28 July 2015
Deviations:
no
Principles of method if other than guideline:
Not applicable
GLP compliance:
yes (incl. certificate)
Remarks:
27 April 2017

Test material

Reference
Name:
Unnamed
Type:
Constituent
Type:
Constituent
Type:
Constituent
Test material form:
liquid
Details on test material:
Appareance: yellow to orange-yellow liquid
Odor : characteristic
Batch number: MN16 081-1
Expiration date: 01 feb 2018
Storage conditions: Room Temp. (20 ± 5°C), keep away from light/ humidity, keep under inert gas
Purity: 100%wt (UVCB substance)
Specific details on test material used for the study:
SOURCE OF TEST MATERIAL
- Batch No. of test material: MN16 081-1
- Date received: 06 January 2017
- Manufacturing date: March 2016
- Expiry date: February 2018
- Purity test date: April 2016

STABILITY AND STORAGE CONDITIONS OF TEST MATERIAL
- Storage condition of test material: Room temperature

TREATMENT OF TEST MATERIAL PRIOR TO TESTING
- Treatment of test material prior to testing: Used as supplied

Test animals / tissue source

Species:
other: Reconstructed human Cornea-like Epithelia
Details on test animals or tissues and environmental conditions:
- Description of the cell system used: 0.60 cm² Reconstructed human Cornea-like Epithelia [EpiOcular(TM) OCL-212-ver2.0, supplied by MatTek Corporation, batch No. 23767] were received on 21 February 2017.

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): 50 µL
- Concentration (if solution): Undiluted
Duration of treatment / exposure:
30 minutes at 37°C, 5% CO2, 95% humidity (standard culture conditions)
Duration of post- treatment incubation (in vitro):
- Post-exposure immersion period: 12 minutes at room temperature
- Post-exposure incubation period: 2 hours and 02 minutes at standard culture conditions
Number of animals or in vitro replicates:
Test item, negative and positive controls were applied on duplicate tissues.
Details on study design:
PRELIMINARY TESTS
- Test for direct interaction with MTT:
The direct interaction of MTT with the test item was checked by adding 16 µL of the test item to 300 µL of MTT solution at 1 mg/mL.
- Test for the detection of the colouring potential of the test item:
The spectral properties at 570 nm of the test item in isopropanol was checked by adding 16 µL of the test item to 1.5 mL of isopropanol.


MAIN TEST
- Pre-incubation of the tissues:
On the day of receipt, the 12 tissues in their 24-well shipping container were equilibrated at room temperature for 15 minutes. Then the inserts (filter + epithelium) were gently removed from the agarose while avoiding leaving agarose on the polycarbonate filter. They were placed in 6 wells culture plate which had been previously filled with 1 mL of 37°C pre-warmed assay medium and incubated during 19 hours and 13 minutes at standard culture conditions.
After the overnight incubation, the tissues were pre-wetted with 20 μL of Ca2+Mg2+Free-DPBS. The tissues were incubated at standard culture conditions for 30 minutes.
- Treatment and post-treatment incubation of the tissues:
The test item was applied, as supplied, at the dose of 50 µL, to the entire surface of 2 living RhCE tissue replicates during 30 minutes at standard culture conditions. In the same experimental conditions, a positive control (Methyl acetate), and a negative control (distilled water) were used. The controls were applied, as supplied, at the dose of 50 µL, to the surface of 2 viable RhCE tissue replicates during 30 minutes at standard culture conditions.
After the treatment, the test item and control substances were carefully washed from the RhCE tissues by extensive rinsing with Ca2+Mg2+Free-DPBS. The rinsed tissues were checked for any colouration and noted for comparable colour with the negative control. This rinsing step was followed by a 12-minute post-exposure immersion period at room temperature in 5 mL of fresh medium to remove any test item absorbed into the tissue. The RhCE constructs were then incubated for a 2-hour and 02-minute post-exposure incubation at standard culture conditions in 1 mL of fresh medium at 37°C, 5% CO2.
- MTT viability assay:
Following the exposure to the test item, viability measurements are performed immediately after the post-exposure incubation period of the rinsed tissues in fresh medium. This period allows both for recovery from weak cytotoxic effects and for appearance of clear cytotoxic effects.
The RhCE tissue viability was measured by enzymatic conversion of the vital dye MTT [3-(4,5-Dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide; Thiazolyl blue tetrazolium bromide; CAS No. 298-93-1] by the viable cells of the tissue into a blue MTT formazan salt that is quantitatively measured by Optical Density (OD) after extraction from tissues. The measured OD was proportional to the number of living cells.
The RhCE constructs were placed in 300 µL of a MTT solution at 1.0 mg/mL for 3 hours at standard culture conditions. The precipitated blue formazan product was then extracted from the tissues by placing each insert in 2 mL of isopropanol during 17 hours and 23 minutes at 6±3°C in the dark. The concentration of formazan was measured by determining the OD at 570 nm, just after dilution of the extractions in isopropanol (1:2). The OD measurement of formazan extracts at 570 nm was measured in triplicate samples using the ELx800 absorbance microplate reader (controlled every year and calibrated if necessary) supplied by BioTek and the validated software Gen5 ELISA V1.05.11 supplied by BioTek.

Results and discussion

In vitro

Results
Irritation parameter:
other: % mean viability of the tissues
Run / experiment:
Main test
Value:
13.53
Vehicle controls validity:
not applicable
Negative controls validity:
valid
Positive controls validity:
valid
Remarks on result:
positive indication of irritation
Other effects / acceptance of results:
PRELIMINARY TESTS
- Test for direct interaction with MTT:
A yellow solution was observed after 3 hours of incubation between 36.4°C and 37.8°C, 5% CO2. Therefore, there is no direct interaction between the test item and MTT.
- Test for the detection of the colouring potential of the test item:
A colourless solution was obtained in isopropanol after 2 hours of incubation at ambient temperature with gentle shaking. The mean of the corrected OD (blank subtracted) was 0.000 which was less than 0.08 (value corresponding to approximately twice the OD of the extracting solvent). Therefore the test item was considered to be not interfering with the MTT assay.

MAIN TEST
- MTT assay results: The mean percent tissue viability of the RhCE replicates treated with the test substance was 13.53%, versus 35.37% in the positive control (Methyl acetate). The mean percent tissue viabilities obtained with the positive control and negative controls were within the range of historical data and therefore validate the experiment. Refer Tables 7.3.2/1 for more details.

Any other information on results incl. tables

Table 7.3.2/1: Main test - Individual and mean corrected OD values and tissue viabilities for the test item, the negative and positive controls

 

Tissue

OD

Mean OD/disc (#)

Mean OD/product

Viability %

Mean viability %

Difference of viability %

Negative control

1

0.840

0.899

0.909

98.90

100.00

2.20

0.931

0.928

2

0.903

0.919

101.10

0.909

0.945

Positive control

1

0.307

0.314

0.322

34.54

35.37

1.65

0.317

0.318

2

0.326

0.329

36.19

0.325

0.337

Test item

1

0.109

0.114

0.123

12.54

13.53

1.98

0.118

0.116

2

0.130

0.132

14.52

0.133

0.135

#: mean of 3 values (triplicate of the same extract)

OD: optical density

Applicant's summary and conclusion

Interpretation of results:
other: Category 2 (irritating to eyes) or Category 1 (irreversible effects on the eye) based on GHS criteria
Conclusions:
Under the test conditions and in accordance with Regulation EC No. 1272/2008, the test substance was identified as potentially requiring classification and labelling according to UN GHS (Category 2 or Category 1).
Executive summary:

An in vitro eye irritation test using the Reconstructed human Cornea-like Epithelium (RhCE) (EpiOcular™ tissue) model was performed according to the OECD Guideline 492 and in compliance with GLP to predict the acute eye irritation potential of the test substance.

The test substance was applied, as supplied, at the dose of 50 µL to 2 living DPBS pre-treated RhCE (EpiOcular™ tissue model) during 30 minutes at 37°C, 5% CO2, 95% humidity (standard culture conditions). The exposure period was followed by extensive rinsing with PBS at room temperature, a 12-minute post-exposure immersion period at room temperature and a 2-hour and 2-minute post-exposure incubation at standard culture conditions. The tissue viability was measured by performing an MTT assay.

In the preliminary tests, the test substance was found not to have direct MTT reducing properties or colouring potential. In the main test, the mean percent tissue viability of the RhCE replicates treated with the test substance was 13.53%, versus 35.37% in the positive control (Methyl acetate). The mean percent tissue viabilities obtained with the positive control and negative controls were within the range of historical data and therefore validate the experiment.

Under the test conditions and in accordance with Regulation EC No. 1272/2008, the test substance was identified as potentially requiring classification and labelling according to UN GHS (Category 2 or Category 1).