3'-nitroacetophenone

Endpoint summary

Description of key information

Skin irritation

The dermal irritation potential of test article 3'-nitro acetophenone (CAS No.- 121-89-1)  was determined according to the OECD 439 test guideline followed for this study. The Mean % tissue viability compared to negative control (n=3) of the test substance 3'-nitro acetophenone was determined to be 103.0 %. Thus, 3'-nitro acetophenone (CAS No.- 121-89-1) was considered to be not irritating to the human skin.

Eye Irritation:

The ocular irritation potential of test article 3'-nitroacetophenone (CAS No.- 121-89-1) was determined according to the OECD 492 test guideline followed for this study. The mean % tissue viability of test substance 3'-nitroacetophenone was determined to be 66.9%. Thus, substance 3'-nitroacetophenone (CAS No.- 121-89-1) is considered to be "not irritating" to the human eye.

Key value for chemical safety assessment

Skin irritation / corrosion

Link to relevant study records

Reference

Endpoint:

skin irritation: in vitro / ex vivo

Type of information:

experimental study

Adequacy of study:

key study

Study period:

May 05, 2017 to July 17, 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 439 (In Vitro Skin Irritation: Reconstructed Human Epidermis Test Method)

Principles of method if other than guideline:

The purpose of this study was to assess potential for the test articles to be dermal irritants. The dermal irritation potential of test article 3'-nitro acetophenone (CAS No.- 121-89-1) may be predicted by measurement of their cytotoxic effect, as reflected in the 3-(4,5-dimethyl thiazol-2-yl)-2,5- diphenyl tetrazolium bromide (MTT) assay, in the MatTek EpiDerm™ model (MatTek Corp., Ashland, MA).

GLP compliance:

yes

Specific details on test material used for the study:

SOURCE OF TEST MATERIAL
- Test material identity: 3'-nitro acetophenone (CAS No.- 121-89-1)
- Source: Loba Chemie Laboratory Reagents and Fine Chemicals
- Lot No.of test material: LB33531602
- Molecular formula: C8H7NO3
- Molecular weight: 165.15
- Manufacture date: Feb-2016
- Expiration date of the lot/batch: Jan-2021
- Physical Appearance: Yellow powder
- Purity: 99.8%
- Melting range: 76-79 degC

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
- 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: Powder

OTHER SPECIFICS: No data available

Test system:

human skin 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:

- 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 epidermis. 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 EpiDerm™ 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 are included in this report. Tissue plates were appropriately labeled with study information.

Justification for test system used:

The 3-Dimensional Human Dermal Epithelial Model (EpiDerm™, MatTek, Ashland, MA) is made up of normal human keratinocytes in serum free medium. The cells form an epithelial tissue that consists of organized basal, spinous, granular, and cornified layers analogous to those found in vivo. The EpiDerm™ model also contains epidermis-specific differentiation markers such as pro-filaggrin, the K1/K10 cytokeratin pair, involucrin, and type I epidermal transglutaminase, as well as keratohyalin granules, tonofilament bundles, desmosomes, and a multi-layered stratum corneum containing intercellular lamellar lipid layers arranged in patterns characteristic of in vivo epidermis. 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). Tissue plates were appropriately labeled with study information. Bias was not a factor in this test system.

Vehicle:

unchanged (no vehicle)

Details on test system:

The tissues were exposed to the test article 3'-nitroacetophenone neat (undiluted) on June 28, 2017 (Run 1 of 1). EpiDerm™ 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 1 hour, with 35 minutes in an approximately 37°C, 5% CO2 humidified incubator and the remaining 25 minutes at room temperature. Following the exposure time, the tissues were rinsed and placed in fresh media for approximately 24 hours. The media was then changed again and the tissues were incubated in fresh media for another ~18 hours for a total of approximately 42 hour post-exposure recovery period. The tissue viability was then assessed by MTT assay. The tissue CoA was used instead of verification of barrier properties of the tissue.

MTT and Color Pre-tests
Pretesting for MTT auto-reduction and coloring was not performed for this study but was based on the results obtained from another study (CYP1690_R1b).

MTT Assay
Following the rinsing period, the MTT assay was performed by transferring the tissues to 24-well plates containing 300 µL MTT medium (1.0 mg/mL). After 2 hours, 57 minute and 25 second MTT incubation at approximately 37°C, approximately 5% CO2 in a humidified incubator, the blue formazan salt was extracted by submerging tissues in 2 mL isopropanol in a 24-well plate. The extraction time was approximately 2 hours 04 minutes and 11 seconds with gentle shaking. 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 is 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 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 articles 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 3'-nitroacetophenone, 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 3'-nitro acetophenon 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):
·        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.

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.

Tested compound :
·        Calculate the blank corrected value ODTT= ODTTraw– ODblank.
·        The OD mean per tissue was calculated.
·        The viability per tissue was calculated: %TT = [ODTT/ mean ODNC] x 100.
·        The mean viability for all tissues was calculated: Mean TT = Σ %TT / number of tissues.
·        The standard deviation (SD), standard error of the mean (SEM) and the percent coefficient of variation (% CV) was calculated.

Data Correction Procedure for MTT Interfering Compounds (if applicable)
True viability = Viability of treated tissue – Interference from test article = ODtvt– ODktwhere 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 (if applicable)
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

- Evaluation of data
The results of the assay was evaluated and compared to negative control.  
Table: Criteria for in vitro Interpretation:
In VitroResults In VivoPrediction
Mean tissue viability ≤50% Irritant (I), R38
Mean tissue viability >50% Non-irritant (NI)

- 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:

The exposure times were approximately 1 hour, with ~35 minutes exposure in the incubator and ~25 minutes at room temperature.

Duration of post-treatment incubation (if applicable):

For a total of an approximately 42 hour post-exposure incubation.

Number of replicates:

3 tissues were used for test compound and control.

Irritation / corrosion parameter:

% tissue viability

Run / experiment:

Run 1

Value:

103

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:

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 1.5 passing the acceptance criteria. The Standard Deviation, initially caused the test articles to not pass acceptance criteria (reported as 24.6 which is >18%) but after removing a single outlier, it has passed the acceptance criteria.

Interpretation of results:

other: not irritating

Conclusions:

The dermal irritation potential of test article 3'-nitro acetophenone (CAS No.- 121-89-1) was determined according to the OECD 439 test guideline followed for this study. The Mean % tissue viability compared to negative control (n=3) of the test substance 3'-nitro acetophenone was determined to be 103.0 %. Thus, 3'-nitro acetophenone (CAS No.- 121-89-1) was considered to be not irritating to the human skin.

Executive summary:

The dermal irritation potential of test article 3'-nitro acetophenone (CAS No.- 121-89-1) 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 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 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 1.5 passing the acceptance criteria.

 

The Mean % tissue viability compared to negative control (n=3) of the test substance 3'-nitro acetophenone was determined to be 103.0 %.

 

Hence, under the experimental test conditions it was concluded that test substance 3'-nitro acetophenone (CAS No.- 121-89-1) 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 article 3'-nitro acetophenone (CAS No.- 121-89-1) may be predicted by measurement of its cytotoxic effect, as reflected in the 3-(4,5-dimethyl thiazol-2-yl)- 2,5-diphenyltetrazolium bromide (MTT) assay, in the MatTek EpiOcular™ model (MatTek Corp., Ashland, MA).

GLP compliance:

yes

Specific details on test material used for the study:

SOURCE OF TEST MATERIAL
- Test material identity: 3'-nitro acetophenone (CAS No.- 121-89-1)
- Source: Loba Chemie Laboratory Reagents and Fine Chemicals
- Lot No.of test material: LB33531602
- Molecular formula: C8H7NO3
- Molecular weight: 165.15
- Manufacture date: Feb-2016
- Expiration date of the lot/batch: Jan-2021
- Physical Appearance: Yellow powder
- Purity: 99.8%
- Melting range: 76-79 degC

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
- 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: Powder

OTHER SPECIFICS: No data available

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:

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

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 article 3'-nitroacetophenone 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 article 3'-nitroacetophenone 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 article 3'-nitroacetophenone 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 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'-nitroacetophenone 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 3'-nitroacetophenone were added to the tissues as a fine powder. The tissue s 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:

66.9

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:

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 3.1 passing the acceptance criteria.

Interpretation of results:

other: not irritating

Conclusions:

The ocular irritation potential of test article 3'-nitroacetophenone (CAS No.- 121-89-1) was determined according to the OECD 492 test guideline followed for this study. The mean % tissue viability of test substance 3'-nitroacetophenone was determined to be 66.9%. Thus, substance 3'-nitroacetophenone (CAS No.- 121-89-1) is considered to be "not irritating" to the human eye.

Executive summary:

The ocular irritation potential of test article 3'-nitroacetophenone (CAS No.- 121-89-1) 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 3.1 passing the acceptance criteria.

 

The mean % tissue viability of test substance 3'-nitroacetophenone was determined to be 66.9%.  

Hence, under the experimental test condition it was concluded that test substance 3'-nitroacetophenone (CAS No.- 121-89-1) is considered to be not irritating to the human eye and being classified as “Not classified’’ as per CLP Regulation.

Endpoint conclusion

Endpoint conclusion:

no adverse effect observed (not irritating)

Respiratory irritation

Endpoint conclusion

Endpoint conclusion:

no study available

Additional information

Skin Irritation:

Various studies has been investigated for the test chemical of 3'-nitroacetophenone (CAS No: 121-89-1)to observe the potential for dermal irritation to a greater or lesser extent. The studies are based on in vitro and in vivo experiments for target chemical Calcium distearate (CAS No: 1592-23-0) and its structurally similar read across substances 3-nitrobenzoic acid (CAS No: 121-92-6)which has been summarized as follows;

 

The dermal irritation potential of test article 3'-nitro acetophenone (CAS No.- 121-89-1) 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 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 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 1.5 passing the acceptance criteria.

 The Mean % tissue viability compared to negative control (n=3) of the test substance 3'-nitro acetophenone was determined to be 103.0 %.

Hence, under the experimental test conditions it was concluded that test substance 3'-nitro acetophenone (CAS No.- 121-89-1) was considered to be not irritating to the human skin and being classified as “Not Classified'' as per CLP Regulation.

 

 These results are further supported by 2 experimental studies conducted in humans and rabbits by Bret Berner et.al (Journal of Toxicology: Cutaneous and Ocular Toxicology, 8:4, 481-492,1989) for thestructurally similar read across substance 3-nitrobenzoic acid (CAS:121-92-6).

Prior to the human study a Preliminary Skin Irritation Study was performed on rabbits to assess the irritation potency of 3-nitrobenzoic acid. The test chemical was applied onto rabbit skin and reactions were scored (dose and duration not specified). 3-nitrobenzoic acid was observed to be not irritating to rabbit skin.

 Sixteen female subjects ranging from 35 to 45 years of age consented to the human irritation 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 3-nitrobenzoic acid 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 standard 0-4 visual scales, with an additional scale at 0.5 to signify borderline reaction. Blood flow assessed by laser Doppler velocimetry (LDV Med Pacific LD5000,Seattle, WA) 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 3-nitrobenzoic acid was 1.0±1.3. It can be considered that 3-nitrobenzoic acid was not irritating to human skin.

The read across studies also affirms the possibility of 3- nitroacetophenone being not irritating to skin.

 

Therefore, Based on available data on target and Read across chemical, 3-nitroacetophenone can be considered to be not irritating to skin.Comparing the above annotations with the criteria of CLP regulation, test chemical can be classified under the category “Not Classified”.

Eye Irritation:

In different studies,3- nitroacetophenone has been investigated for potential for ocular irritation to a greater or lesser extent. The studies are based on in vitro and in vivo experiments along with predicted data for target chemical and its functionally similar read across substances;9,10-anthraquinone (CAS: 84-65-1) and 2-(1,3-dihydro-3-oxo-2H-indol-2-ylidene)-1,2-dihydro-3H-indol-3-one [Indigo Blue] (CAS: 482-89-3).

The ocular irritation potential of test article 3'-nitroacetophenone (CAS No.- 121-89-1) 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 3.1 passing the acceptance criteria.

 The mean % tissue viability of test substance 3'-nitroacetophenone was determined to be 66.9%.  

Hence, under the experimental test condition it was concluded that test substance 3'-nitroacetophenone (CAS No.- 121-89-1) is considered to be not irritating to the human eye and being classified as “Not classified’’ as per CLP Regulation.

The ocular irritation potential of 3-nitroacetophenone [HSDB (Hazardous Substances Data Bank); US National Library of Medicine reviewed by SRC;last updated 2002]was evaluated in rabbits.The test chemical was instilled into rabbit eyes and effects were observed for 24 hours. The effects were graded on a scale 1-10 after 24 hours. 3 Nitro acetophenone was rated 1 on scale of 1 to 10 according to degree of injury observed after 24 hr. The most severe injuries have been rated 10. Therefore,3 Nitro acetophenone can be considered to be not irritating to rabbit eyes.

The above results are further supported by the experimental study conducted by JOSE J. ESTABLE (American Journal of Ophthalmology; Volume 31, Issue 7, July 1948, Pages 837-844) for the functionally similar read across substance 9,10-anthraquinone (CAS: 84-65-1).White rabbits were used for the study. Anthraquinone(dry powder)was placed in the lower conjunctival sac of one eye and held there usually for one-half minute. This was repeated at intervals of one or several days.The other eye was treated with 0.7% solution of Sodium chloride and used as control. The eyes were examined for evidence of inflammation, and changes in the corneal structures were observed with the bio-microscope. Anthraquinone produced only immediate sensory and inflammatory reaction (discomfort, blepharospasm, and conjunctival congestion) that disappeared very soon. The eyes appeared normal in a few hours. Hence, it was concluded the irritation effects were due to mechanical action of the powder rather than toxic effects of anthraquinone.

Therefore, Anthraquinone can be considered not irritating to eyes.

 

These results are also supported by the experimental study summarized in HSDB (Hazardous Substances Data Bank); US National Library of Medicine reviewed by SRC; last updated 2003; for the functionally similar read across substance 2-(1,3-dihydro-3-oxo-2H-indol-2-ylidene)-1,2-dihydro-3H-indol-3-one [Indigo Blue] (CAS: 482-89 -3). A man accidently splashed 7% alkaline solution of Indigo Blue into his eyes. The conjunctiva appeared blue after several hours. Cornea was somewhat turbid but not stained. In course of 10 days cornea gradually got cleared and some fine blue dots were seen in stroma. Indigo blue appeared to be rather inert & nontoxic in tissues.

Based on the observations, Indigo Blue can be considered not irritating to human eyes.

The read across studies also affirms the possibility of 3-nitroacetophenone being not irritating to eyes.

Therefore,based on available data on target and Read across substance, 3- nitroacetophenone can be considered to be not irritating to eyes.Comparing the above annotations with the criteria of CLP regulation, test chemical can be classified under the category “Not Classified”.

Justification for classification or non-classification

Available studies for 3- nitroacetophenone indicate that it is not irritating to skin and eyes.

3- nitroacetophenone can be classified under the category "Not Classified" for eyes and skin as per CLP regulation.