3-nitrobenzoic acid

Endpoint summary

Description of key information

Skin irritation

There was no skin reaction observed at test item applied area. The mean erythema and edema scores were 0.0 at all observation times. Hence, it was concluded that the test chemical was Non-Irritating to the skin of Wistar rats under the experimental conditions tested and classified as “Category-Not Classified” as per CLP Classification.

The Mean % tissue viability compared to negative control (n=3) of the test chemical was determined to be 12.3 %.

Hence, under the experimental test conditions it was concluded that test chemical was considered to be irritating to the human skin and being classified as ''Irritating to skin in Category 2” as per CLP Regulation

Eye Irritation

The mean % tissue viability of test chemical was determined to be 1.9%.

Hence, under the experimental test conditions it was concluded that test chemical was considered to be an eye irritant and being classified as “Irritating to eyes in Category 2” as per CLP Regulation.

Key value for chemical safety assessment

Skin irritation / corrosion

Link to relevant study records

Reference

Reference 1

Endpoint:

skin irritation: in vivo

Type of information:

experimental study

Adequacy of study:

key study

Reliability:

1 (reliable without restriction)

Rationale for reliability incl. deficiencies:

comparable to guideline study

Justification for type of information:

data is from experimental reports

Qualifier:

according to guideline

Guideline:

other: OECD Guideline 402 (Acute Dermal Toxicity)

Principles of method if other than guideline:

To assess the toxicological profile of the test chemical on application as a single semi-occlusive dermal application to rats

GLP compliance:

yes

Species:

rat

Strain:

Wistar

Details on test animals or test system and environmental conditions:

Details on test animals
Sex: females, Females were nulliparous and non-pregnant
Source :Vivo Bio Tech Ltd, Gajwel Mandal, Medak District, Telangana
Age at treatment: 8 to 10 weeks
Body weight range at treatment: Females: 213.42 to 248.13 g
Identification :By rat accession number. Identification of individual rats is by cage card and crystal violet colour body markings. The temporary body marking during acclimatization period was done with crystal violet. The rat accession numbers were allotted during the course of the study and was included in raw data and reported.
Housing: Animals were housed individually in standard polysulfone cages (Size: L 425 x B 266 x H 185 mm), with stainless steel top grill having facilities for pelleted food and drinking water in polycarbonate bottle. Steam sterilized corn cob was used and changed once a week along with the cage.
Diet:Rat & Mice pellet feed, manufactured by Krishna Valley Agro Tech LLP, MIDC Kupwad block, Sangli, Maharashtra, was provided ad libitum to animals
Water: Purified water in polycarbonate bottles with stainless steel sipper tubes was provided ad libitum
Acclimatization:After physical examination for good health and suitability for experiment, the rats were acclimatized for six, eight, twelve and fourteen days before treatment for dose range finding and main study respectively under standard laboratory conditions. Animals were observed once daily during acclimatization period.

Environmental Conditions:
Temperature: temperature 20 to 24°C
Relative humidity: 57 to 67 %,
Air changes: Animals were housed under standard laboratory conditions, air conditioned with adequate fresh air supply (12.9 to 14.0 air changes/hour)
Photoperiod (hrs dark / hrs light): 12 hours light and 12 hours dark cycle
In Life dates: Start: 31 March, 2018 , End: 24 April, 2018

Type of coverage:

occlusive

Preparation of test site:

clipped

Vehicle:

water

Controls:

not specified

Amount / concentration applied:

TEST MATERIAL
- Amount(s) applied (volume or weight with unit):
DRF G1 2000 mg/kgbw
Main G1 2000mg/kgbw

- Concentration (if solution): 2000 mg/kg (G2) was weighed on an aluminum foil and made into a paste by adding sufficient volume (about 0.5 mL) of Milli-Q water

VEHICLE
- Amount(s) applied (volume or weight with unit): 0.5 ml

Duration of treatment / exposure:

24 hours

Observation period:

Treatment site at was observed for erythema and edema at 24, 48 and 72 hours after removal of test item using the Draize criteria

Number of animals:

3- [1- DRF; 2- Main]

Details on study design:

TEST SITE
- Area of exposure: clipped skin of the torso
- % coverage: 10% of the body surface of the animal (semi-occlusive).
- Type of wrap if used: The area of application was covered with cotton gauze (size: Females: 8 x 5 cm of 6 ply) and it was secured in position by adhesive tape wound around the torso
REMOVAL OF TEST SUBSTANCE
- Washing (if done): yes
- Time after start of exposure: After the 24 hours contact period, the dressing was removed and the applied area was washed with deionized water and wiped dry using clean towels

OBSERVATION TIME POINTS
(indicate if minutes, hours or days) : All the rats were observed for clinical signs of toxicity and mortality for 14 days post application. In addition, the treatment site was observed at 24, 48 and 72 hours after
removal of test item using the Draize criteria
SCORING SYSTEM:
- Method of calculation: Draize method

Irritation parameter:

erythema score

Basis:

mean

Time point:

24/48/72 h

Score:

0

Reversibility:

not specified

Remarks on result:

no indication of irritation

Irritation parameter:

edema score

Basis:

mean

Time point:

24/48/72 h

Score:

0

Reversibility:

not specified

Remarks on result:

no indication of irritation

Irritant / corrosive response data:

There were no skin reactions at the site of application at 24, 48 and 72 hours after test patch removal (as per Draize method).

Other effects:

There were no clinical signs and pre-terminal deaths (mortality) observed during the study. All rats gained body weight throughout the observation period.

APPENDIX 1.      Individual test item application, clinical signs, skin reactionand necropsy findings

Dose range finding study

 

Group & Dose (mg/kg body weight)

Date and time of application

Rat Number

S e x

Initial Bwt (g)

Quantity (mg) applied

Observations and skin reaction

Days

1

2

3

4

5

30 min

1 h

2 h

3 h

4 h

5 h

6 h

*

Er @

Ed @

*

Er @

Ed @

*

Er @

Ed @

G1 and 2000 DRF

05 April 2018 and 10.13 AM

Rm8761

F

231.51

463

N

N

N

N

N

N

N

N

N

0

0

N

0

0

N

0

0

 

Group & Dose (mg/kg body weight)

Rat Number

S e x

Observation

Necropsy findings

Days

6

7

8

9

10

11

12

13

14

15

G1 and 2000 DRF

Rm8761

F

N

N

N

N

N

N

N

N

N

N

NAD

F: Female             N: Normal          h: hour    min: minutes                      NAD: No abnormality detected      Er: Erythema                      Ed: Edema  

Score 0: No Erythema / Edema       

    

*: Clinical signs; @: Skin scoring as per Draize method (approximately 24, 48 and 72 hours) after test patch removal

 

Main study

 

Group & Dose (mg/kg body weight)

Date and time of application

Rat Number

S e x

Initial Bwt (g)

Quantity (mg) applied

Observations and skin reaction

Days

1

2

3

4

5

30 min

1 h

2 h

3 h

4 h

5 h

6 h

*

Er @

Ed @

*

Er @

Ed @

*

Er @

Ed @

G1 and 2000 Main

10 April 2018 and 10.18AM and 10.20 AM

Rm8762

F

248.73

497

N

N

N

N

N

N

N

N

N

0

0

N

0

0

N

0

0

Rm8763

F

213.42

427

N

N

N

N

N

N

N

N

N

0

0

N

0

0

N

0

0

 

Group & Dose (mg/kg body weight)

Rat Number

S e x

Observations

Necropsy findings

Days

6

7

8

9

10

11

12

13

14

15

G2 and 2000 Main

Rm8762

F

N

N

N

N

N

N

N

N

N

N

NAD

Rm8763

F

N

N

N

N

N

N

N

N

N

N

NAD

F: Female             N: Normal          h: hour    min: minutes                       NAD: No abnormality detected      Er: Erythema                       Ed: Edema  

Score 0: No Erythema / Edema          

*: Clinical signs; @: Skin scoring as per Draize method (approximately 24, 48 and 72 hours) after test patch removal

 

 

Interpretation of results:

other: not irritating

Conclusions:

There was no skin reaction observed at test item applied area. The mean erythema and edema scores were 0.0 at all observation times. Hence, it was concluded that the test chemical was Non-Irritating to the skin of Wistar rats under the experimental conditions tested and classified as “Category-Not Classified” as per CLP Classification.

Executive summary:

A study was designed and conducted to determine the dermal reaction profile of the test chemical in Wistar rats. The study was performed as per OECD Guidelines 402 and complying to the GLP procedures.

1 female for the dose range finding study, followed by additional 2 females rats for main study.

Based on the individual body weight, the test item at the dose of 2000 mg/kg body weight was weighed on an aluminum foil and made as a paste in Milli-Q water and applied directly to the clipped skin (clipping was done approximately 24 hour prior to application) of the animal to cover about 10% of the body surface of the animal (semi-occlusive). The area of application was covered with cotton gauze (size: Females: 8 x 5 cm of 6 ply) and it was secured in position by adhesive tape wrapped around the torso. The test item contact period with the skin was for 24 hours.

After the 24 hours contact period, the adhesive tape and cotton gauge was removed and the applied area was washed with deionized water and wiped dry using clean towels.

All the rats were observed for clinical signs of toxicity and mortality for 14 days post application. In addition, the treatment site was observed at 24, 48 and 72 hours after removal of test item using the Draize criteria. There were no clinical signs of toxicity and mortality.

There was no skin reaction observed at test item applied area. The mean erythema and edema scores were 0.0 at all observation times. Hence, it was concluded that the test chemical was Non-Irritating to the skin of Wistar rats under the experimental conditions tested and classified as “Category-Not Classified” as per CLP Classification.

Reference 2

Endpoint:

skin irritation: in vitro / ex vivo

Type of information:

experimental study

Adequacy of study:

key study

Study period:

December 04, 2017 to March 13, 2018

Reliability:

1 (reliable without restriction)

Rationale for reliability incl. deficiencies:

guideline study

Justification for type of information:

Data is from experimental study report

Qualifier:

according to guideline

Guideline:

OECD Guideline 439 (In Vitro Skin Irritation: Reconstructed Human Epidermis Test Method)

Principles of method if other than guideline:

The purpose of this study is to provide classification of dermal irritation potential of a chemical by using a three-dimensional human epidermis model, according to the OECD Test Guideline No. 439, “In Vitro Skin Irritation: Reconstructed Human Epidermis Test Method”.

GLP compliance:

yes

Specific details on test material used for the study:

Name of the test chemical: 3-nitrobenzoic acid
Molecular Formula: C7H5NO4
Molecular Weight: 167.1195 g/mol
SMILES: c1(cc(ccc1)[N+](=O)[O-])C(=O)O
Substance Type: Organic
Physical State: Solid

SOURCE OF TEST MATERIAL
Lot no. : -851551512
Mfg date : -DEC,2015
Exp date :-NOV-2020

RADIOLABELLING INFORMATION (Not applicable)
- Radiochemical purity: N/A
- Specific activity: N/A
- Locations of the label: N/A
- Expiration date of radiochemical substance: N/A

STABILITY AND STORAGE CONDITIONS OF TEST MATERIAL
- Storage condition of test material: Room temperature or Fridge storage
- Stability under test conditions: No data available
- Solubility and stability of the test substance in the solvent/vehicle: No data available
- Reactivity of the test substance with the solvent/vehicle of the cell culture medium: No data available

TREATMENT OF TEST MATERIAL PRIOR TO TESTING
- Treatment of test material prior to testing: Test articles is tested as provided (neat).
- Preliminary purification step (if any): No data available
- Final dilution of a dissolved solid, stock liquid or gel: No data available
- Final preparation of a solid: No data available

FORM AS APPLIED IN THE TEST: Solid

OTHER SPECIFICS:
Assay: Min. 98.0% results: 98.0% .
Melting range: 139 -142"C, results: 140 -142'C

Test system:

human skin model

Remarks:

MatTek EpiDerm™ Tissue Model

Source species:

human

Cell type:

non-transformed keratinocytes

Cell source:

other: EpiDerm™ 3-dimensional human tissues used in this study

Source strain:

other: Not applicable

Details on animal used as source of test system:

EpiDerm™ tissues, Lot No. 27646 Kits I and J, were received from MatTek on 12 Dec 2017, and Lot No. 27654 Kits O and P, were received from MatTek on 19 Dec 2017. All tissues were refrigerated at 2-8°C upon receipt. Before use, the tissues were incubated (37±1°C, 5±1% CO2) with assay medium (MatTek) for a one-hour equilibration. The tissues were then moved to new wells with fresh medium for an additional overnight equilibrium, for 18±3 hours. Equilibration medium was replaced with fresh medium before dosing.

Justification for test system used:

The EpiDerm™ Skin Model closely parallels human skin, thus providing a useful in vitro means to assess dermal irritancy and toxicology

Vehicle:

unchanged (no vehicle)

Details on test system:

EpiDerm™ Tissue Samples
EpiDerm™ tissues, Lot No. 27646 Kits I and J, were received from MatTek on 12 Dec 2017, and Lot No. 27654 Kits O and P, were received from MatTek on 19 Dec 2017 All tissues were refrigerated at 2-8°C upon receipt. Before use, the tissues were incubated (37±1°C, 5±1% CO2) with assay medium (MatTek) for a one-hour equilibration. The tissues were then moved to new wells with fresh medium for an additional overnight equilibrium, for 18±3 hours. Equilibration medium was replaced with fresh medium before dosing.

Mesh Compatibility
Five of the test articles supplied were liquids. These test articles were assessed for compatibility with pre-cut nylon mesh supplied with the tissues. The mesh was placed on a slide and 30 μl of a liquid test articles or PBS (negative control) were applied. After 60 minutes of exposure, the mesh was checked microscopically. If no damage or other interaction was observed, indicating that the mesh was compatible with the test article, the mesh was used as a spreading aid.

Tissue Viability (MTT Reduction)
At the end of the incubation period, each EpiDerm™ tissue was rinsed with PBS and transferred to a 24-well plate containing 300 μl of MTT solution (1 mg/ml MTT in DMEM). The tissues were then returned to the incubator for a three-hour MTT incubation period. Following the MTT incubation period, each EpiDerm™ tissue was rinsed with PBS and then treated with 2.0 ml of extractant solution (isopropanol) per well for at least two hours, with shaking, at room temperature. Two aliquots of the extracted MTT formazan were measured at 540 nm using a plate reader (μQuant Plate Reader, Bio-Tek Instruments, Winooski, VT).
For several tissues, the test article had stained the tissues. Therefore, the tissues were extracted with only 1.0 ml, allowing extraction to occur only through the bottom of the insert. After the extraction period, the tissue insert was removed and discarded and 1.0 ml of extraction solution were added to each well, bringing the volume to a total of 2.0 ml.

Quality Controls
The assay meets the acceptance criteria if the mean OD540 of the negative control tissues is between 1.0 and 2.5, inclusive, and the mean viability of positive control tissues, expressed as percentage of the negative control tissues, is at least 20%. In addition, the standard deviation (SD) calculated from individual percent tissue viabilities of the three identically-treated replicates must be less than 18%.
Note: Chemicals that provide tissue viabilities in a range of 30% to 70% may provide high SD. If the high SD (above acceptance limits) is typical for the chemical and the classification of the chemical is consistent in all independent runs, MatTek recommends that this result be accepted, although it did not meet the Assay Acceptance Criterion.

Analysis of Data
See Table 1 for Experimental Data. The mean absorbance value for each time point was calculated from the optical density (OD) of the duplicate samples and expressed as percent viability for each sample using the following formula:
% viability = 100 X (OD sample/OD negative control)

Skin Irritation Prediction
According to the EU1,2 and GHS3 classification (R38 / Category 2 or no label), an irritant is predicted if the mean relative tissue viability of three individual tissues exposed to the test substance is 50% or less of the mean viability of the negative controls.

In vitro result In vivo Classification
Mean tissue viability ≤ 50% Category 2
Mean tissue viability > 50% Non-irritant (NI)


Assessment of direct MTT reduction and assessment of coloring or staining materials was not performed. Therefore, it cannot be fully assessed if the test articles interfered with MTT viability measurements.

Retention of Data
Upon signing the final report, all raw data, supporting documentation and reports are submitted to the Archivist by the Study Director. The raw data are filed at MB Research by project number. The final report is filed at MB Research by Sponsor name and MB project number.
All data generated during the conduct of this study will be archived at MB Research for at least one year from the date of the final report and optionally longer at additional cost. The Sponsor will be contacted in writing to determine final disposition of the records.
Any remaining test article will be discarded upon submission of the report.

Amendment to the Protocol
There were no amendments to the protocol. See Appendix C for the protocol in its entirety
Evaluation of Test Article in the Cell Models:
1. Cell system: Upon receipt, the MatTek EpiDerm™ tissue cultures were placed in 0.9 mL of fresh Maintenance medium (in a 6-well plate). The culture inserts are incubated for ~one hour. The tissues were then transferred to 6-well plates containing 0.9 mL fresh Maintenance medium and they were incubated overnight at ~37°C, 5% CO2 in a humidified incubator.

2. Control and Test Article Exposures: On the day of dosing, the tissues are then removed from the incubator and the controls and the test article are applied topically to tissues by pipette. Tissues were exposed to controls and the test articles for one hour, with ~35 minutes in a 37°C, 5% CO2 humidified incubator and the remaining 25 minutes at room temperature.

a) Controls
30 µL of negative control DPBS, positive control 5% SDS was applied topically to the tissue and gently spread by placing a nylon mesh on the apical surface of each tissue, if necessary.

b)Test Article
For solid test article, the tissues were moistened with 25 μL of ultrapure water to improve contact of the tissue surface with the test article. Approximately 25 mg of each test article was evenly applied to the apical surface of each tissue (n=3). All the tissues were placed into the ~37°C incubator with 5% CO2. The exposure times were approximately 1 hour, with ~35 minutes exposure in the incubator and ~25 minutes at room temperature.

3.Post-exposure treatment
After the 1 hour exposure, the tissues were rinsed 20 to 25 times with 1 mL of DPBS. The apical surface was gently blotted with a cotton swab. The tissues were placed in 0.9 mL of fresh Maintenance medium (6-well plate) for either 25 hours, 38 minutes and 23 seconds or for 24 hours, 10 minutes and 09 seconds (as there were numerous tissues, they had to be broken down into 2 sets to complete dosing in a timely manner). After this initial ~24 hour incubation, the tissues were placed in 6-well plates containing 0.9 mL fresh Maintenance medium and incubated for another 17 hours, 03 minutes and 34 seconds prior to performing the MTT assay, for a total of an approximately 42 hour post-exposure incubation.

RECONSTRUCTED HUMAN EPIDERMIS (RHE) TISSUE
- Model used: The EpiDerm™ 3 dimensional human tissue model
- Tissue Lot number(s): 26459
- Date of initiation of testing: 6/08/2017

TEMPERATURE USED FOR TEST SYSTEM
- Temperature used during treatment / exposure: 37°C
- Temperature of post-treatment incubation (if applicable): 37°C

REMOVAL OF TEST MATERIAL AND CONTROLS
-Volume and number of washing steps: Twice

MTT DYE USED TO MEASURE TISSUE VIABILITY AFTER TREATMENT / EXPOSURE
- MTT concentration: 300 µL MTT medium (1.0 mg/mL).
- Incubation time: After 2 hours, 57 minute and 25 second MTT incubation
- Spectrophotometer: Synergy H4 spectrophotometer
- Wavelength: 570 nm
- Filter: No data
- Filter bandwidth: No data
- Linear OD range of spectrophotometer: No data

NUMBER OF REPLICATE TISSUES: 3

CALCULATIONS and STATISTICAL METHODS
All data were background subtracted before analysis. MTT data are presented as % viable compared to negative control. Data were generated as follows:

MTT Assay
Blanks:
·        The optical density (OD) mean from all replicates for each plate (ODblank).

Negative Controls (NC):
Identity: Phosphate-Buffered Saline (PBS), Lot No. AC10239794
Provided by:MatTek
Date Received:12 Dec 2017 and 19 Dec 2017
Expiration Date:18 Jul 2018
Storage:Room temperature and humidity
Description:Clear colorless liquid
Sample Preparation:Used as received

Positive Control (PC):
Identity: 5% Sodium Dodecyl Sulfate (SDS), Lot No. 071817MAB
Provided by:MatTek
Date Received:12 Dec 2017 and 19 Dec 2017
Expiration Date:18 Jul 2018
Storage:Room temperature and humidity
Description:Clear colorless liquid
Sample Preparation:Used as received

- Assay quality controls
- Negative Controls (NC)
The Dulbecco’s phosphate buffered saline (DPBS) was used as a NC. The assay passed all acceptance criteria if the ODs of the negative control exposed tissues were between ≥0.8 and ≤2.8.
 
- Positive Controls (PC)
5% solution of sodium dodecyl sulfate was used as a PC. The assay is meeting the acceptance criteria if the viability of the PC is ≤20% of the negative control.
 
- Standard Deviation (SD)
The standard deviation (SD) calculated from individual percent tissue viabilities of the test article exposed replicates was ≤18.

Control samples:

yes, concurrent negative control

yes, concurrent positive control

Amount/concentration applied:

TEST MATERIAL
- Amount(s) applied (volume or weight with unit): 25 mg
- Concentration (if solution): neat (undiluted)

VEHICLE (Not used)
- Amount(s) applied (volume or weight with unit): none
- Concentration (if solution): none
- Lot/batch no. (if required): none
- Purity: none

NEGATIVE CONTROL
- Amount(s) applied (volume or weight): 30 µL
- Concentration (if solution): neat

POSITIVE CONTROL
- Amount(s) applied (volume or weight): 30 µL
- Concentration (if solution): 5% solution of sodium dodecyl sulfate

Duration of treatment / exposure:

Tissues will be topically exposed to the test article and control articles for 60 minutes.

Duration of post-treatment incubation (if applicable):

After dosing, the tissues will be returned to the incubator for 35 ±1 minute, and then returned to the sterile hood for the remainder of the 60-minute exposure period.

Number of replicates:

All treatments with test articles and controls will be dosed in triplicate EpiDerm™ tissues.

Irritation / corrosion parameter:

% tissue viability

Run / experiment:

Run 1

Value:

86

Vehicle controls validity:

not specified

Negative controls validity:

valid

Positive controls validity:

valid

Remarks on result:

no indication of irritation

Other effects / acceptance of results:

All treatments with test articles and controls will be dosed in triplicate EpiDerm™ tissues.

In vitro result In vivo Classification
Mean tissue viability ≤ 50% Category 2
Mean tissue viability > 50% Non-irritant

Test and Control Article Identity	Tissue Viability		Irritancy Classification	GHS Category
	Mean	SD
Test chemical	86T.0%	17.75%	Non-Irritant	No Category

 

Test and control article identity	Tissue no.	Raw data		Blank corrected data		Mean of aliquots	% viability	OD		Viabilities(%)		CV%	Classification
								MEAN	SD	Mean	SD
		Aliq 1	Aliq 2	Aliq 1	Aliq 2
Test chemical	1	1.284	1.344	1.238	1.298	1.268	68.7	1.588	0.328	86.0	17.75	20.64	Not irritating
	2	1.614	1.624	1.568	1.578	1.573	85.2

Interpretation of results:

other: not irritating

Conclusions:

The dermal irritation potential of test article was determined according to the OECD 439 test guideline followed for this study. The Mean % tissue viability compared to negative control (n=3) of test chemical was determined to be 86.0%. Thus, test chemical was considered to be not irritating to the human skin.

Executive summary:

The dermal irritation potential of test article was determined according to the OECD 439 In Vitro Skin Irritation: Reconstructed Human Epidermis Test Method”. The MatTek EpiDerm™ model was used to assess the potential dermal irritation of the test article by determining the viability of the tissues following exposure to the test article via MTT. The objective of this study was to assess the dermal irritation potential of test article Tissues were exposed to test article and controls for ~one hour, followed by a 42 hour post-exposure recovery period. The viability of each tissue was determined by MTT assay. 

The MTT data shows that the assay quality controls were met, as the OD of the negative control tissues was between 1.195 and 1.430. Also, the positive control, 5% sodium dodecyl sulfate (SDS), reduced tissue viability to 4.5% of negative control.

The Mean % tissue viability compared to negative control (n=3) of test chemical was determined to be 86.0%.

Hence, under the experimental test conditions it was concluded that test chemical was considered to be not irritating to the human skin and being classified as “Not Classified'' as per CLP Regulation.

Endpoint conclusion

Endpoint conclusion:

no adverse effect observed (not irritating)

Eye irritation

Link to relevant study records

Reference

Endpoint:

eye irritation: in vitro / ex vivo

Type of information:

experimental study

Adequacy of study:

key study

Study period:

May 05, 2017 to July 12, 2017

Reliability:

1 (reliable without restriction)

Rationale for reliability incl. deficiencies:

guideline study

Justification for type of information:

Data is from experimental study report.

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)

Principles of method if other than guideline:

The purpose of this study was to assess potential for the test article to be ocular irritants. The ocular irritation potential of a test chemical may be predicted by measurement of its cytotoxic effect, as reflected in the 3-(4,5-dimethyl thiazol-2-yl)-2,5-diphenyl tetrazolium bromide (MTT) assay, in the MatTek EpiOcular™ model (MatTek Corp., Ashland, MA).

GLP compliance:

yes

Species:

human

Strain:

other: Not applicable

Details on test animals or tissues and environmental conditions:

- Description of the cell system used
The normal human-derived keratinocytes were cultured at the air-liquid interface in a chemically defined medium on a permeable polycarbonate insert (surface 0.5 cm2). They were cultured in chemically defined serum free medium to form a multi-layered epithelium similar to that found in native corneal mucosa. Each lot of tissues was Quality Assured by MatTek according to specific QC standards including: histology, tissue viability (MTT mean optical density), reproducibility (SD) and tissue thickness.

- Test System Identification
All of the EpiOcular™ 3-dimensional human tissues used in this study were identified by the date of arrival and the lot number. Certificate of Analysis for the tissues is included in this report. Tissue plates were appropriately labeled with study information. Bias was not a factor in this test system.

- Justification of the test method and considerations regarding applicability
Human Corneal Epithelia (HCE) by MatTek, Inc.:
The test article and controls were evaluated for potential ocular irritancy using the EpiOcular™ 3 dimensional human tissue model purchased from MatTek Corporation (Ashland, MA). This model consists of normal human keratinocytes cultured on a permeable synthetic membrane at the air-liquid interface in a chemically defined medium. The cells form a stratified, squamous corneal epithelium resembling the corneal mucosa of the human eye. This model has been used with several common tests of cytotoxicity including MTT and interleukin 1-alpha (IL-1α). A growing body of evidence indicates that EpiOcular™ effectively provides a non-animal means to assess potential irritancy. The EpiOcular™ model closely mimics the human corneal mucosa and thus provides an important in vitro approach in the evaluation of ocular irritancy and toxicity. Each lot of tissues was Quality Assured by MatTek, Inc. according to specific QC standards including: histology (cell layers), tissue viability (MTT mean optical density) and reproducibility (SD).

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
- Concentration (if solution): neat (undiluted)

VEHICLE (no vehicle)
- Amount(s) applied (volume or weight with unit): none
- Concentration (if solution): none
- Lot/batch no. (if required): none
- Purity: none

NEGATIVE CONTROL
- Amount(s) applied (volume or weight): 50 µL
- Concentration (if solution): neat

POSITIVE CONTROL
- Amount(s) applied (volume or weight): 50 µL
- Concentration (if solution): neat

Duration of treatment / exposure:

Tissues were exposed for approximately ~6 hours for test article and controls, at approximately 37°C, 5% CO2 in a humidified incubator.

Observation period (in vivo):

Not applicable

Duration of post- treatment incubation (in vitro):

Following the post soak, the tissues were rinsed and incubated at approximately 37°C, 5% CO2 in a humidified incubator for a post-exposure recovery time totaling ~18 hours for test article and controls.

Number of animals or in vitro replicates:

3 tissues were used for test compound and control.

Details on study design:

- Details of the test procedure used
The tissues were exposed to the test chemical neat (undiluted). EpiOcular™ tissues were purchased from MatTek. Quality control of the tissues was performed by MatTek and the Certificate of Analysis (CoA) for the tissues is provided and is kept in the study binder. Tissues were exposed for approximately ~6 hours for test article and controls, at approximately 37°C, 5% CO2 in a humidified incubator. After the exposure, the test article was rinsed off the tissues and the tissues were soaked in media for ~25 minutes for test article and controls. Following the post soak, the tissues were rinsed and incubated at approximately 37°C, 5% CO2 in a humidified incubator for a post-exposure recovery time totaling ~18 hours for solid test article and controls. Tissue viability was assessed by 3-(4,5-dimethylthiazol -2-yl)-2,5-diphenyltetrazolium bromide (MTT) assay.

- MTT Auto reduction and colouring assessment
- MTT Pre-test
~50 mg of test chemical was added to 1 mL of MTT media (~1 mg/mL) and incubated in a humidified incubator at approximately 37°C and approximately 5% CO2 for 2 hours, 55 minutes and 02 seconds. 50 µL of ultrapure water was used as a negative control.

- Test Article Color Test
Approximately 50 mg of test chemical was added to 1.0 mL of ultrapure water and 2.0 mL isopropanol and incubated in a humidified incubator at approximately 37°C and approximately 5% CO2 for 2 hours, 04 minutes and 35 seconds. Samples were then added to the wells of a clear 96-well plate and the plate was read on a BioTek Synergy H4 (or equivalent) plate reader set to 570 nm. Test article that tested positive for excessive coloration (OD >0.08) were assessed on living-tissue controls that were incubated in both culture media and MTT media as well (n=3 for both conditions).

- MTT Assay
After the recovery period, the MTT assay was performed on run 1 tissues by transferring the tissues to 24-well plates containing 300 µL MTT medium (1.0 mg/mL). After 2 hours 55 minutes and 00 seconds (solids) of MTT incubation at approximately 37°C, approximately 5% CO2 in a humidified incubator, the tissues were rinsed twice with DPBS. The blue formazan salt was extracted by submerging tissues in 2 mL isopropanol in a 24-well plate. The extraction time was 2 hours 00 minutes with gentle shaking for solid exposed tissues. The optical density of the extracted formazan (200 µL/well of a 96-well plate) was determined using a Synergy H4 spectrophotometer at 570 nm. Relative cell viability was calculated for each tissue as % of the mean negative control tissues.

- Evaluation of Test Article in the cell Models
1. Cell System:
Upon receipt, the MatTek EpiOcular™ tissue cultures were placed in 1.0 mL of fresh Maintenance medium (in a 6-well plate) for 59 minutes and 00 seconds. The tissues were not incubated overnight.

Control and Test Article Exposures:
20 µL of calcium and magnesium free DPBS was added to each tissue and the tissues placed back into the incubator for 31 minutes 00 seconds. The controls and the test article will be applied topically to tissues by pipette. Three tissues will be used per test compound and control.

a)Controls:
50 µL of negative control sterile ultrapure water, positive control methyl acetate were added to the tissues. The tissues were placed into the ~37°C humidified incubator with 5% CO2 for the approximately 6 hour exposure time.

b)Test Article:
Approximately 50 mg of the test article 3-nitrobenzoic acid were added to the tissues as a fine powder. The tissues were placed into the ~37°C humidified incubator with 5% CO2 for the approximately 6 hour exposure time.

3. Post exposure treatment
After the exposure, the tissues were rinsed 20 to 25 times with ~1 mL of DPBS to remove test material. The apical surface was gently blotted with a cotton swab and cultures were immediately transferred to a 12-well plate containing 5 mL of media per well. Tissues exposed to solid test article (and the respective control) were incubated, submerged in the media for ~25 minutes at room temperature. Tissuses were then transferred to 6-well plates containing 1.0 mL fresh Maintenance medium per well and incubated for a post-exposure recovery period for 17 hours 48 minutes 01 seconds at approximately 37 degC, 5% CO2 in a humidified incubator.

- Doses of test chemical and control substances used
a)Test Article:
Approximately 50 mg of the test chemical were added to the tissues as a fine powder. The tissues were placed into the ~37°C humidified incubator with 5% CO2 for the approximately 6 hour exposure time.

b)Controls:
50 µL of negative control sterile ultrapure water, positive control methyl acetate were added to the tissues. The tissues were placed into the ~37°C humidified incubator with 5% CO2 for the approximately 6 hour exposure time.

- Duration and temperature of exposure, post-exposure immersion and post-exposure incubation periods:
Tissues were exposed for approximately ~6 hours for test article and controls, at approximately 37°C, 5% CO2 in a humidified incubator.
Following the post soak, the tissues were rinsed and incubated at approximately 37°C, 5% CO2 in a humidified incubator for a post-exposure recovery time totaling ~18 hours for test article and controls.

- Justification for the use of a different negative control than ultrapure H2O (Not applicable)

- Justification for the use of a different positive control than neat methyl acetate (Not applicable)

- Number of tissue replicates used per test chemical and controls: 3 tissues were used for test compound and control.

- Description of the method used to quantify MTT formazan
The blue formazan salt was extracted by submerging tissues in 2 mL isopropanol in a 24-well plate. The extraction time was 2 hours 00 minutes with gentle shaking for solid exposed tissues. The optical density of the extracted formazan (200 µL/well of a 96-well plate) was determined using a Synergy H4 spectrophotometer at 570 nm.

- Description of evaluation criteria used including the justification for the selection of the cut-off point for the prediction model
Calculations and Statistical Methods
MTT Assay
Blanks:
·  The OD mean from all replicates for each plate (ODblank).

Negative Controls (NC):
·  The blank corrected value was calculated: ODNC= ODNCraw– ODblank.
·  The OD mean per NC tissue was calculated.
·  The mean OD for all tissues corresponds to 100% viability.
·  The mean, standard deviation (SD), standard error of the mean (SEM) and the percent coefficient of variation (% CV) was calculated.

ODblank= optical density of blank samples (isopropanol alone).
ODNCraw= optical density negative control samples.
ODNC= optical density of negative control samples after background subtraction.

Positive Control (PC):
·        Calculate the blank corrected value: ODPC= ODPCraw– ODblank.
·        The OD mean per PC tissue was calculated.
·        The viability per tissue was calculated: %PC = [ODPC/ mean ODNC] x 100.
·        The mean viability for all tissues was calculated: Mean PC = Σ %PC / number of tissues.
·        The standard deviation (SD), standard error of the mean (SEM) and the percent coefficient of variation (% CV) was calculated.
ODPCraw= optical density positive control samples.
ODPC= optical density of positive control samples after background subtraction.

Tested Articles:
·  Calculate the blank corrected value ODTT= ODTTraw– ODblank.
·  The OD mean per tissue is calculated.
·  The viability per tissue is calculated: %TT = [ODTT/ mean ODNC] x 100.
·  The mean viability for all tissues is calculated: Mean TT = Σ %TT / number of tissues.
·  The standard deviation (SD) and the percent coefficient of variation (% CV)for the controls and the test articles will be calculated.
ODTTraw= optical density test article samples.
ODPC= optical density of test article samples after background subtraction.

Data Correction Procedure for MTT Interfering Compounds
True viability = Viability of treated tissue – Interference from test article = ODtvt – ODkt where ODkt = (mean ODtkt – mean ODukt).
ODtvt = optical density of treated viable tissue
ODkt = optical density of killed tissues
ODtkt = optical density of treated killed tissue
ODukt = optical density of untreated killed tissue (NC treated tissue)

Data Correction Procedure for Colored Compounds
True viability = Viability of treated tissue incubated in MTT media – Viability of treated tissue incubated in media without MTT = ODtvt – ODvt.
ODtvt = optical density of treated viable tissue incubated in MTT media
ODvt = optical density of viable tissues incubated in media alone.

Proposed Statistical methods
The mean, standard deviation (SD) and the percent coefficient of variation (% CV) for the controls and the test article will be calculated.

- Evaluation of data
The results of the assay was evaluated and compared to negative control.

Table: Irritancy Prediction
In VitroResults In VivoPrediction
Mean tissue viability ≤60% Irritant (I) – Category 1 or 2
Mean tissue viability >60% Non-irritant (NI) – No Category

- Assay quality controls
- Negative Controls (NC)
The assay is meeting the acceptance criterion if the mean viability of the NC in terms of Optical Density (OD570) of the NC tissues (treated with sterile ultrapure water) in the MTT assay are >0.8 to <2.5. This is an indicator of tissue viability following shipping and conditions under use.
 
- Positive Controls (PC)
Methyl acetate was used as a PC and tested concurrently with the test article. The assay is meeting the acceptance criteria if the viability of the PC is <50% of the negative control.
 
- Standard Deviation (SD)
Each test of ocular irritancy potential is predicted from the mean viability determined on 3 single tissues. The assay meets the acceptance criteria if SD calculated from individual percent tissue viabilities of the replicates is <18% for three replicate tissues.

 

Irritation parameter:

other: mean % tissue viability

Run / experiment:

Run 1

Value:

1.9

Vehicle controls validity:

not specified

Negative controls validity:

valid

Positive controls validity:

valid

Remarks on result:

positive indication of irritation

Other effects / acceptance of results:

The MTT data show the assay quality controls were met, as the OD of the negative control tissues was between 0.981 and 1.284 in run 1. Also, the positive control, methyl acetate, reduced tissue viability to be 11.3% of negative control (for 6 hour exposures with solids) in run one and the standard deviation (SD) calculated from individual percent tissue viabilities of the test article exposed replicates was 0.3 passing the acceptance criteria.

	Mean       (% Viability)	SD	%CV
Water (Solids)	100.0	3.6	3.6
Water (Run 2)	100.0	2.4	2.4
Methyl Acetate (Solids)	11.3	5.3	46.7

121 -92 -6

1.9

0.3

16.4

Interpretation of results:

Category 2 (irritating to eyes) based on GHS criteria

Conclusions:

The ocular irritation potential of test chemical was determined according to the OECD 492 test guideline followed for this study. The mean % tissue viability of test chemical was determined to be 1.9%. Thus, the test chemical was considered to be an eye irritant.

Executive summary:

The ocular irritation potential of test chemical was determined according to the OECD 492 test guideline followed for this study. The MatTek EpiOcular™ model was used to assess the potential ocular irritation of the test articles by determining the viability of the tissues following exposure to the test article via MTT. The objective of this study was to assess the ocular irritation potential of test article. Tissues were exposed to test article and controls for ~6 hours, followed by a ~25 minute post-soak and approximately 18 hour recovery after the post-soak. The viability of each tissue was determined by MTT assay. 

 

The MTT data show the assay quality controls were met, as the OD of the negative control tissues was between 0.981 and 1.284 in run 1. Also, the positive control, methyl acetate, reduced tissue viability to be 11.3% of negative control (for 6 hour exposures with solids) in run one and the standard deviation (SD) calculated from individual percent tissue viabilities of the test article exposed replicates was 0.3 passing the acceptance criteria.

 

The mean % tissue viability of test chemical was determined to be 1.9%.

 

Hence, under the experimental test conditions it was concluded that test chemical was considered to be an eye irritant and being classified as “Irritating to eyes in Category 2” as per CLP Regulation.

Endpoint conclusion

Endpoint conclusion:

adverse effect observed (irritating)

Respiratory irritation

Endpoint conclusion

Endpoint conclusion:

no study available

Additional information

Skin Irritation

Various studies have been summarized to assess the degree of dermal irritation caused by the test chemical in living organisms. The studies include in vivo experimental data on rats, rabbits, humans as well as in vitro experimental data for the test chemical. The results are summarized as follows:

A study was designed and conducted to determine the dermal reaction profile of the test chemical in Wistar rats. The study was performed as per OECD Guidelines 402 and complying to the GLP procedures. 1 female for the dose range finding study, followed by additional 2 females rats for main study.

Based on the individual body weight, the test item at the dose of 2000 mg/kg body weight was weighed on an aluminum foil and made as a paste in Milli-Q water and applied directly to the clipped skin (clipping was done approximately 24 hour prior to application) of the animal to cover about 10% of the body surface of the animal (semi-occlusive). The area of application was covered with cotton gauze (size: Females: 8 x 5 cm of 6 ply) and it was secured in position by adhesive tape wrapped around the torso. The test item contact period with the skin was for 24 hours. After the 24 hours contact period, the adhesive tape and cotton gauge was removed and the applied area was washed with deionized water and wiped dry using clean towels. All the rats were observed for clinical signs of toxicity and mortality for 14 days post application. In addition, the treatment site was observed at 24, 48 and 72 hours after removal of test item using the Draize criteria. There were no clinical signs of toxicity and mortality. There was no skin reaction observed at test item applied area. The mean erythema and edema scores were 0.0 at all observation times. Hence, it was concluded that the test chemical was Non-Irritating to the skin of Wistar rats under the experimental conditions tested and classified as “Category-Not Classified” as per CLP Classification.

 

These results are supported by a Human skin irritation study conducted to assess the irritation potential of the test chemical. Sixteen female subjects ranging from 35 to 45 years of age consented to the study. Ten were of Hispanic origin with various degrees of olive-complected skin. Five were white with type II skin, and one was a white/Polynesian mixture with a slightly olive skin tone. All subjects had reasonably clear backs with no or few comedones, moles, or freckles. On day 1 the subjects acclimated for a half hour during which time the sites was marked on the back with a felt tip marker. The scapular regions of the upper back un-occluded by undergarments were tested. A column of five test sites were marked on each side, avoiding the midline. This accommodated two replicates per subject for the test chemical and a distilled water control. The position of each treatment within a side of the back was randomized. Baseline scoring and measurements were taken. The relative humidity and temperature were noted. The 12 loaded test discs were applied to the skin occluded with 3%ethylene vinyl acetate (EVA) membrane and secured with tape (Scanpore Norgeplaster 6, Oslo, Norway). On day 2 the patches were removed and the sites marked again. Thirty minutes later, the measurements were repeated. Erythema and edema were scored by standard0-4visual scales, with an additional scale at0.5to signify borderline reaction. Blood flow assessed by laser Doppler velocimetry (LDV Med Pacific LD5000, USA) and color (reflected light color analyzer by Minolta Chroma Meter CR-100) were measured. On day 3 the procedure of day 2 was repeated. Primary irritation index (PII) was calculated as the average for the two time points of the sum of the erythema and edema scores. The average PII of 24 and 48 hours scores for the test chemical was 1.0±1.3. It can be considered that the test chemical was not irritating to human skin.

 

In the third study from peer reviewed journal preliminary Skin Irritation Study was performed to assess the irritation potential of the test chemical in rabbits. The test chemical was applied onto rabbit skin and reactions were scored (dose and duration not specified). The test chemical was considered to be not irritating to rabbit skin.

 

This is supported by an in vitro study according to the OECD 439 In Vitro Skin Irritation: Reconstructed Human Epidermis Test Method”. The MatTek EpiDerm™ model was used to assess the potential dermal irritation of the test article by determining the viability of the tissues following exposure to the test article via MTT. The objective of this study was to assess the dermal irritation potential of test article Tissues were exposed to test article and controls for ~one hour, followed by a 42 hour post-exposure recovery period. The viability of each tissue was determined by MTT assay. The MTT data shows that the assay quality controls were met, as the OD of the negative control tissues was between 1.195 and 1.430. Also, the positive control, 5% sodium dodecyl sulfate (SDS), reduced tissue viability to 4.5% of negative control. The Mean % tissue viability compared to negative control (n=3) of test chemical was determined to be 86.0%. Hence, under the experimental test conditions it was concluded that test chemical was considered to be not irritating to the human skin and being classified as “Not Classified'' as per CLP Regulation.

 

The dermal corrosion potential of the test chemical was determined by using a three-dimensional human epidermis model, according to OECD Test Guideline No. 431 “In Vitro Skin Irritation: Reconstructed Human Epidermis (RHE) Test Method”. The EpiDermTMSCT allows discrimination between non-corrosive and corrosive chemicals according to the UN Globally Harmonized System of Classification and Labeling of Chemicals (GHS). The MatTek EpiDermTM tissue cultures were obtained from MatTek In Vitro Life Science Laboratories. The MatTek EpiDermTMtissue cultures were placed in the refrigerator at 5°C. Prior to use, the tissues were incubated (37±1°C, 5±1% CO2) in 0.9 mL of fresh maintenance medium in 6 -well plates for one hour. Before dosing, the tissues were moistened with 25microliter of sterile water to improve the contact of the tissue surface to the test article. Approximately 25 mg of solid test article was evenly applied to the apical surface of each tissue. Each treatment with test article or control was conducted in duplicate. The exposure period for the test articles and controls was 3 and 60 minutes. For the 60-minute exposure, the dosed tissues were placed in an incubator at 37±1°C, 5±1% CO2for the remainder of the 60-minute exposure period. Following the rinsing period, the MTT assay was performed by transferring the tissues to 24-well plates containing 300microliter MTT medium (1.0 mg/mL). After 3 hours of incubation at 37±1°C, 5±1% CO2in a humified incubator, the blue formazan salt was extracted by submerging the tissues in 2 mL isopropanol (Lot # 28677, Kit A; provided by MatTek, Slovakia) in a 24-well plate. The extraction time was approximately 2 hours and 05 minutes with gentle shaking. The optical density of the extracted formazan (200mL/well if a 96-well plate) was determined using a Thermo Scientific™ Multiskan™ FC Microplate Photometer at 570 nm. Relative cell viability was calculated for each tissue as % of the mean negative control tissue. A chemical was regarded to be corrosive if the relative tissue viability after 3 min treatment with a test chemical was decreased below 50%. In addition, materials were regarded to be non-corrosive after 3 min (viability>50%) were regarded to be corrosive if the relative tissue viability after 1-hour treatment with a test chemical was decreased below 15%. The dermal corrosion potential of the test chemical was determined by using a three-dimensional human epidermis model, according to OECD Test Guideline No. 431 “In Vitro Skin Corrosive: Reconstructed Human Epidermis (RHE) Test Method”. The mean tissue viability of the test chemical at 3 minutes and 60 minutes exposure time were 2.178 % and 0.240 % respectively. The Mean % tissue viability compared to negative control (n=3) of the test chemical was determined to be 88.9 % and 10.2 % for 3 min. endpoint and 1 hour endpoint, respectively. Based on these values, the test chemical can be considered to corrosive to skin. It can be further classified under the category "Category 1" as per CLP Regulation.

 

 

The dermal irritation potential of test chemical was determined according to the OECD 439 test guideline followed for this study. The MatTek EpiDerm™ model was used to assess the potential dermal irritation of the test article by determining the viability of the tissues following exposure to the test article via MTT. The objective of this study was to assess the dermal irritation potential of test article. Tissues were exposed to test articles and controls for ~one hour, followed by a 42 hour post-exposure recovery period. The viability of each tissue was determined by MTT assay.  The MTT data show the assay quality controls were met, as the OD of the negative control tissues was between 1.195 and 1.430. Also, the positive control, 5% sodium dodecyl sulfate (SDS), reduced tissue viability to 4.5% of negative control and the standard deviation (SD) calculated from individual percent tissue viabilities of the test article exposed replicates was 8.9 passing the acceptance criteria. The Mean % tissue viability compared to negative control (n=3) of the test chemical was determined to be 12.3 %. Hence, under the experimental test conditions it was concluded that test chemical was considered to be irritating to the human skin and being classified as ''Irritating to skin in Category 1” as per CLP Regulation.

 

Even though results of in-vitro studies claim that the test chemical causes severe irritation to skin, but in vivo experimental studies indicate a strong possibility that the test chemical can be not irritating to skin.Also, when tested at the maximum dose of 2000mg/kg in rats; no signs of irritation were observed till 14 days of observation.

Taking all these factors into consideration, the test chemical can be considered to be not irritating to skin. Comparing the above annotations with the criteria of CLP Regulation, the test chemical can be classified under the category “Not Classified”.

Eye Irritation

Eye irritation

In several studies, the potential of the test chemical to cause ocular irritation was studied to a greater or lesser extent. The studies include in vivo experimental data on rabbits as well in vitro data for the test chemicals. The results are mentioned as follows:

The ocular irritation potential of test chemical was determined according to the OECD 492 test guideline followed for this study. The MatTek EpiOcular™ model was used to assess the potential ocular irritation of the test articles by determining the viability of the tissues following exposure to the test article via MTT. The objective of this study was to assess the ocular irritation potential of test article. Tissues were exposed to test article and controls for ~6 hours, followed by a ~25 minute post-soak and approximately 18 hour recovery after the post-soak. The viability of each tissue was determined by MTT assay. 

The MTT data show the assay quality controls were met, as the OD of the negative control tissues was between 0.981 and 1.284 in run 1. Also, the positive control, methyl acetate, reduced tissue viability to be 11.3% of negative control (for 6 hour exposures with solids) in run one and the standard deviation (SD) calculated from individual percent tissue viabilities of the test article exposed replicates was 0.3 passing the acceptance criteria.

 

The mean % tissue viability of test chemical was determined to be 1.9%.

 Hence, under the experimental test conditions it was concluded that test chemical was considered to be an eye irritant and being classified as “Irritating to eyes in Category 1 or 2” as per CLP Regulation.

This in vitro result is supported by similar study performed according to OECD 492 to evaluate the ocular irritation potential of test article. The MatTek EpiOcular™ model was used to assess the potential ocular irritation of the test articles by determining the viability of the tissues following exposure to the test article via MTT. Tissues were exposed to solid test articles and control for approx.6 hours, followed by a 25 minute post-soak and approximately 18 hours recovery after the post-soak. The viability of each tissue was determined by MTT assay.

The MTT data show the assay quality controls were met, passing the acceptance criteria.

The mean % tissue viability of test substance was determined to be 2.7%. Hence, under the experimental test conditions it was concluded that test substance was considered to be irritating to the human eyes and can thus be classified as ‘’Irritating to eyes in Category 2” as per CLP Regulation

The above in vitro results are supported by another OECD 492 Guideline study performed to determine the ocular irritation potential of test article. The MatTek EpiOcular™ model was used to assess the potential ocular irritation of the test article by determining the viability of the tissues following exposure to the test article via MTT. The objective of this study was to assess the ocular irritation potential of test article. Tissues were exposed to test article and controls for ~6 hours, followed by a ~25 minute post-soak and approximately 18 hour recovery after the post-soak. The viability of each tissue was determined by MTT assay. 

The MTT data show the assay quality controls were met, as the OD of the negative control tissues was between 0.8 to 2.5 in run 1.

The mean % tissue viability of test chemical was determined to be 2.0%. Thus, test chemical was considered to be irritating to MatTek EpiOcular Tisssue Model OCL-200.

These in vitro results are supported by an in vivo study performed according to OECD 405 Guidelines to determine the acute ocular irritation potential of the test chemical on rabbits.

0.1 ml bulk volume (about 43 mg of comminuted test substance) was applied to the conjuctival sac of the right eyelid of 3 [one male and two female] Vienna White rabbits. The untreated eyes served as control. Readings were taken 1,24,48 and 72 hours till 8 days after the application. Clinical symptoms were observed within one hour of the application and at the end of observations period (8 days), symptoms like loss of corneal tissue, loss of hair at the margins of eyelid, marginal vascularization of the cornea, small retractions in the eyelid were observed.

The mean scores for cornea, iris score and conjuctivae were 3.2, 0.1 and 1.7 respectively.

Based on the scores, the test chemical was considered to be irritating to rabbit eyes.

These results are further supported by a Draize test conducted on rabbits to determine the adverse effects caused by the test chemical. The chemical produced PII value of 34 out of maximum score of 110 when the chemical installed into the eye of each rabbit. Therefore, the test chemical was considered to be Moderately irritating to the eye of rabbits.

The primary eye irritation potential of the test chemical was also evaluated according to Draize method.

3 female Japanese White rabbits (2.0-2.2 kg) were used for the study. The chemical (if solid= 100 mg, if liquid = 0.1ml) was instilled into the conjunctival sac of the left eye.Right eye (untreated eye) served as blank control.The eyes were examined and the grade of ocular lesions was recorded at 1, 24, 48, 72, 96 hours and 7, 14, 21 days after administration of test chemical. Corneal opacity, erythema, chemosis, secreta and iritis were recorded and classified under Draize method (Draize et.al, 1944).The sum of values, recorded for cornea, conjunctiva and iris was divided by the number of observation times and the average scores (Draize scores) were used as grades of ocular irritation potential of the chemical

The maximum value of Draize score are as follows: Cornea =80, Conjunctiva = 20 and Iris = 5

The average Draize scores after 21 days were as follows: CORNEA = 54.1/80, iris = could not be determined, conjunctiva = 10.3/20.

The test chemical induced severe eye irritation not recovering within 21 days of treatment.

Hence, the test chemical can be assessed as irritating to rabbit eyes.               

Based on the results from the available studies the test chemical can be considered to cause irritation to eyes. Comparing the above annotations with the criteria of CLP Regulation, the test chemical can be classified under the category “Category 2”.

Justification for classification or non-classification

Even though results of in-vitro study claims that the test chemical causes severe irritation to skin, but in vivo experimental studies indicate a strong possibility that the test chemical can be not irritating to skin.Also, when tested at the maximum dose of 2000mg/kg in rats; no signs of irritation were observed till 14 days of observation.

Taking all these factors into consideration, the test chemical can be considered to be not irritating to skin. Comparing the above annotations with the criteria of CLP Regulation, the test chemical can be classified under the category “Not Classified”.

Based on the results from the available studies the test chemical can be considered to cause irritation to eyes. Comparing the above annotations with the criteria of CLP Regulation, the test chemical can be classified under the category “Category 2”.