Hydratropaldehyde

Eye irritation

Administrative data

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.

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)

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 article Hydratro paldehyde (CAS No.- 93-53-8) may be predicted by measurement of its cytotoxic effect, as reflected in the 3-(4,5-dimethylthiazol-2-yl)- 2,5-diphenyltetrazolium bromide (MTT) assay, in the MatTek EpiOcular™ model (MatTek Corp., Ashland, MA).

GLP compliance:

yes

Test material

Test material information

Constituent 1

Reference substance name:

Hydratropaldehyde

EC Number:

202-255-5

EC Name:

Hydratropaldehyde

Cas Number:

93-53-8

Molecular formula:

C9H10O

IUPAC Name:

hydratropaldehyde

Details on test material:

- Name of test material: Hydratropaldehyde- Molecular formula: C9H10O- Molecular weight: 134.17 g/mol- Smiles notation: CC(C=O)C1=CC=CC=C1- Substance type: Liquid- Physical state: Organic- Impurities (identity and concentrations): No data- Purity: minimum 98%

Specific details on test material used for the study:

SOURCE OF TEST MATERIAL
- Test material identity: Hydratropaldehyde (2-Phenylpropionaldehyde, 97%)
- Source of test material: Alfa Aesar
- Lot No.of test material: 10177315
- Date of analysis: 25.01.2013
- Expiration date of the lot/batch: 25.01.2018
- Purity test date: 96.6%
- Appearance (colour): Clear colourless liquid

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: Freeze 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: The test article tested as provided neat (undiluted).
- 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 (if different from that of starting material): Liquid

OTHER SPECIFICS: No data available

Test animals / tissue source

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 articles 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).

Test system

Vehicle:

unchanged (no vehicle)

Controls:

other: See ''Remark" for Control Samples used in the study

Amount / concentration applied:

TEST MATERIAL
- Amount(s) applied (volume or weight with unit): 50 µL
- 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 30 minutes for liquid 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 ~2 hours for liquid test article and controls.

Number of animals or in vitro replicates:

3 tissues were used per test compound and control.

Details on study design:

- Details of the test procedure used
The tissues were exposed to the test article Hydratropaldehyde 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 30 minutes for liquid test articles 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 ~12 minutes for liquid test articles 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 ~2 hours for liquid 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
The test article was assessed for the potential to interfere with the assay. Approximately 50 µL of liquid test article Hydratropaldehyde 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 µL of Hydratropaldehyde 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 articles 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 50 minutes and 14 seconds (liquids) 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 for liquid exposed tissues was overnight incubation (22 hours 17 minutes and 52 seconds) with a 20 minute 24 second shake the following morning. 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 55 minutes and 16 seconds. The tissues were not incubated overnight.

2. 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 30 minute exposure time.

b)Test Article:
50 µL of Hydratropaldehyde were added to the tissues. The tissues were placed into the ~37°C humidified incubator with 5% CO2 for the approximately 30 minute 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 liquid test articles (and the respective control) were incubated, submerged in the media for ~12 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 2 hours 01 minutes at approximately 37 degC, 5% CO2 in a humidified incubator.

- Doses of test chemical and control substances used
Test Article:
50 µL of Hydratropaldehyde were added to the tissues. The tissues were placed into the ~37°C humidified incubator with 5% CO2 for the approximately 30 minute exposure time.

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 30 minute exposure time.

- Duration and temperature of exposure, post-exposure immersion and post-exposure incubation periods:
Tissues were exposed for approximately 30 minutes for liquid test articles 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 ~2 hours for liquid 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 for liquid exposed tissues was overnight incubation (22 hours 17 minutes and 52 seconds) with a 20 minute 24 second shake the following morning. 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.

 

Results and discussion

In vitro

Results

Irritation parameter:

other: mean % tissue viability

Run / experiment:

Run 1

Value:

29.6

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 22.1% (for 30 minute exposures with liquids) of negative control in run one and the standard deviation (SD) calculated from individual percent tissue viabilities of the test article exposed replicates was 13.9 passing the acceptance criteria.

Applicant's summary and conclusion

Interpretation of results:

other: “Irritating to eyes in Category 1 or 2”

Conclusions:

The ocular irritation potential of test article Hydratropaldehyde (CAS No.- 93-53-8) was determined according to the OECD 492 test guideline followed for this study. The mean % tissue viability of test substance Hydratropaldehyde was determined to be 29.6%. Thus, substance Hydratropaldehyde (CAS No.- 93-53-8) is considered to be an eye irritant.

Executive summary:

The ocular irritation potential of test article Hydratropaldehyde (CAS No.- 93-53-8) 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 liquid test article and controls for ~30 minutes, followed by a ~12 minute post-soak and approximately 2 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 22.1% (for 30 minute exposures with liquids) of negative control in run one and the standard deviation (SD) calculated from individual percent tissue viabilities of the test article exposed replicates was 13.9 passing the acceptance criteria.

The mean % tissue viability of test substance Hydratropaldehyde was determined to be 29.6%.

Hence, under the experimental test conditions it was concluded that test substance Hydratropaldehyde (CAS No.- 93-53-8) is considered to be an eye irritant and being classified as “Irritating to eyes in Category 2” as per CLP Regulation.