Ethyl 9-oxo-9H-thioxanthene-2-carboxylate

Eye irritation

Administrative data

Endpoint:

eye irritation: in vitro / ex vivo

Type of information:

experimental study

Adequacy of study:

key study

Study period:

18 - 19 Jan 2017

Reliability:

1 (reliable without restriction)

Rationale for reliability incl. deficiencies:

guideline study

Data source

Reference

Reference Type:

study report

Title:

Unnamed

Year:

2017

Report date:

2017

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)

Remarks:

OGYÉI, Országos Gyógyszerészeti és Élelmezés-egészségügyi Intézet, Budapest, Hungary

Test material

Test material information

Constituent 1

Reference substance name:

Ethyl 9-oxo-9H-thioxanthene-2-carboxylate

EC Number:

280-960-7

EC Name:

Ethyl 9-oxo-9H-thioxanthene-2-carboxylate

Cas Number:

83817-60-1

Molecular formula:

C16H12O3S

IUPAC Name:

ethyl 9-oxo-9H-thioxanthene-2-carboxylate

Specific details on test material used for the study:

STABILITY AND STORAGE CONDITIONS OF TEST MATERIAL
- Storage condition of test material: at room temperature, dry conditions and protected from heat and direct sunlight

Test animals / tissue source

Species:

human

Details on test animals or tissues and environmental conditions:

- Justification of the test method and considerations regarding applicability
The EpiOcularTM Eye Irritation Test (EIT) was validated by the European Union Reference Laboratory for Alternatives to Animal Testing (EURL ECVAM) and Cosmetics Europe. It was concluded that the EpiOcularTM EIT is able to correctly identify chemicals not requiring classification and labelling for eye irritation or serious eye damage according to UN GHS, and the test method was recommended as scientifically valid for that purpose.
In order to distinguish between Category 1 (corrosive to eye) and Category 2 (eye irritant), further testing is required.

- Description of the cell system used, incl. certificate of authenticity and the mycoplasma status of the cell live
The EpiOcularTM human cell construct (OCL-200-EIT, MatTek Corporation) is used in this assay. It is composed of stratified human keratinocytes in a three-dimensional structure, consisting of at least three viable layers of cells. All biological components of the EpiOcularTM tissue and the kit culture medium have been tested and are free of the presence of viruses, bacteria and mycoplasma.
Analysis for tissue functionality and quality was performed and passed.

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 mg

Duration of treatment / exposure:

6 h ± 15 min

Observation period (in vivo):

Not applicable

Duration of post- treatment incubation (in vitro):

25 ± 2 min (Post-soak)
18 h ± 15 min (Post-treatment incubation)

Number of animals or in vitro replicates:

2 replicates

Details on study design:

- Details of the test procedure used
The cytotoxicity of the test item (and thus the ocular irritation potential) is evaluated by the relative viability of the treated RhCE tissues in comparison to the negative control-treated tissues. Viability is determined by the NAD(P)H-dependent microsomal enzyme reduction of MTT in control and test item treated cultures.

- RhCE tissue construct used, including batch number
The EpiOcularTM human cell construct (OCL-200-EIT, MatTek In Vitro Life Science Laboratories, Bratislava, Slovakia, #23759)

- Doses of test chemical and control substances used
50 mg test item; 50 μL positive control (methyl acetate) ad 50 μL negative control (sterile deionized water)

- Duration and temperature of exposure, post-exposure immersion and post-exposure incubation periods
exposure: 6 h ± 15 min at 37 ± 1 °C
post-exposure immersion: 25 ± 2 min at room temperature
post-exposure incubation: 18 hours ± 15 min at 37 ± 1 °C

- Number of tissue replicates used per test chemical and controls (positive control, negative control, NSMTT, NSCliving and NSCkilled, if applicable)
2 replicates each

- Wavelength and band pass (if applicable) used for quantifying MTT formazan, and linearity range of measuring device (e.g. spectrophotometer)
570 nm

- Description of the method used to quantify MTT formazan
Inserts were removed from the 24-well plate after the incubation time (3 h ± 10 min), the bottom of the insert was blotted on absorbent material and transferred to a 6-well plate containing 2 mL isopropanol per well in a manner avoiding the isopropanol to flow into the insert. The plate was sealed with parafilm. To extract the MTT, the plates were placed on an orbital plate shaker and shaken (150 rpm) for ~3 h at room temperature. 200 μL samples from each tube were placed into the wells of a 96-well plate and the absorbance/ optical density was measured in a 96-well plate spectrophotometer.

- Description of evaluation criteria used including the justification for the selection of the cut-off point for the prediction model
The test item requires classification and labelling according to UN GHS (Category 2 or Category 1), if the mean percent tissue viability after exposure and post-exposure incubation is ≤ 60% of the negative control.
The test item requires no classification and labelling according to UN GHS (No Category), if the mean percent tissue viability after exposure and post-exposure incubation is > 60%.

- Reference to historical positive and negative control results demonstrating suitable run acceptance criteria
yes

- Complete supporting information for the specific RhCE tissue construct used
yes

- Reference to historical data of the RhCE tissue construct
yes

- Demonstration of proficiency in performing the test method before routine use by testing of the proficiency chemicals
no information available from the study report

- Positive and negative control means and acceptance ranges based on historical data
negative control mean OD: 1.899, range: 1.138 - 2.378
positive control mean OD: 0.213, range: 0.064 - 0.500

- Acceptable variability between tissue replicates for positive and negative controls
The difference of viability between the two relating tissues of a single chemical is < 20% in the same run (for positive (22 and 8%) and negative control tissues (93 and 107%) it was 14% and for the tissues of the single chemical (86 and 91%) it was 5%)

- Acceptable variability between tissue replicates for the test chemical
see "Acceptable variability between tissue replicates for positive and negative controls": < 20%

Results and discussion

In vitro

Results

Results 1

Irritation parameter:

other: mean viability (%)

Run / experiment:

negative control

Value:

100

Vehicle controls validity:

not applicable

Negative controls validity:

valid

Positive controls validity:

valid

Results 2

Irritation parameter:

other: mean viability (%)

Run / experiment:

positive control

Value:

15

Vehicle controls validity:

not applicable

Negative controls validity:

valid

Positive controls validity:

valid

Results 3

Irritation parameter:

other: mean viability (%)

Run / experiment:

test item

Value:

89

Vehicle controls validity:

not applicable

Negative controls validity:

valid

Positive controls validity:

valid

Other effects / acceptance of results:

OTHER EFFECTS:
- Visible damage on test system: no

DEMONSTRATION OF TECHNICAL PROFICIENCY: no information available from the study report

ACCEPTANCE OF RESULTS:
- Acceptance criteria met for negative control: Yes, as the mean OD value (1.222) of the two negative control tissues lies between 0.8 and 2.5.
- Acceptance criteria met for positive control: Yes, as the mean percentage viability for the positive control (15%) lies below 50% of the control viability.

Any other information on results incl. tables

Table 1: MTT results of eye irritation study

Controls		Optical Density (OD)	Viability (%)	Δ%
Negative Control: Sterile deionized water	1	1.138	93	14
	2	1.306	107
	mean	1.222	100	-
Positive Control: Methyl acetate	1	0.268	22	14
	2	0.094	8
	mean	0.181	15	-
Test item	1	1.057	86	5
	2	1.112	91
	mean	1.084	89	-
	standard deviation (SD)		3.19	-

 

Applicant's summary and conclusion

Interpretation of results:

other: CLP/ EU GHS criteria not met, no classification required according to Regulation (EC) No 1272/2008

Conclusions:

CLP: not classified