p-toluic acid

Eye irritation

Administrative data

Endpoint:

eye irritation: in vitro / ex vivo

Type of information:

experimental study

Adequacy of study:

key study

Study period:

09 October 2017

Reliability:

1 (reliable without restriction)

Rationale for reliability incl. deficiencies:

guideline study

Data source

Reference

Reference Type:

study report

Title:

Unnamed

Year:

2017

Report date:

2017

Materials and methods

Test guideline

Qualifier:

according to guideline

Guideline:

OECD Guideline 438 (Isolated Chicken Eye Test Method for Identifying i) Chemicals Inducing Serious Eye Damage and ii) Chemicals Not Requiring Classification for Eye Irritation or Serious Eye Damage)

Deviations:

no

GLP compliance:

yes (incl. QA statement)

Test material

Test material information

Constituent 1

Reference substance name:

p-toluic acid

EC Number:

202-803-3

EC Name:

p-toluic acid

Cas Number:

99-94-5

Molecular formula:

C8H8O2

IUPAC Name:

4-methylbenzoic acid

Test material form:

solid: crystalline

Specific details on test material used for the study:

SOURCE OF TEST MATERIAL
- Source and lot/batch No.of test material: CCI Corp.; Bx 20170320
- Expiration date of the lot/batch: 20 March 2018
- Purity test date: 20 march 2017

STABILITY AND STORAGE CONDITIONS OF TEST MATERIAL
- Storage condition of test material: Room temperature (15-25 °C, ≤ 70% Relative Humidity, RH), protected from humidity (tight closed container), protected from light.
- Stability under test conditions: stable
- Solubility and stability of the test substance in the solvent/vehicle: not applicable
- Reactivity of the test substance with the solvent/vehicle of the cell culture medium: not applicable

TREATMENT OF TEST MATERIAL PRIOR TO TESTING
- Treatment of test material prior to testing: none
- Preliminary purification step (if any): none
- Final dilution of a dissolved solid, stock liquid or gel: not applicable
- Final preparation of a solid: ground to fine powder using a mortar and pestle

Test animals / tissue source

Species:

chicken

Strain:

other: ROSS 308 and COBB 500

Details on test animals or tissues and environmental conditions:

SOURCE OF COLLECTED EYES
- Source: TARAVIS KFT. (Address: 9600 Sárvár, Rábasömjéni út. 129., Hungary
- Number of animals: 4 to 5
- Characteristics of donor animals (e.g. age, sex, weight): Approx. 7 weeks old; no infromation on sex or weight.
- Storage, temperature and transport conditions of ocular tissue (e.g. transport time, transport media and temperature, and other conditions): Heads were collected by a slaughter house technician and heads transported to CiToxLAB Hungary Ltd. at ambient temperature at the earliest convenience.
- Time interval prior to initiating testing: within 2 hours
- indication of any existing defects or lesions in ocular tissue samples: none
- Indication of any antibiotics used: none

Test system

Vehicle:

unchanged (no vehicle)

Controls:

yes, concurrent positive control

yes, concurrent negative control

Amount / concentration applied:

TEST MATERIAL
- Amount(s) applied (volume or weight with unit): 30mg

Duration of treatment / exposure:

10 seconds

Duration of post- treatment incubation (in vitro):

The control eyes and test eyes were evaluated pre-treatment and at approximately 30, 75, 120, 180 and 240 minutes after the post-treatment rinse. Minor variations within approximately ±5 minutes were considered acceptable.

Number of animals or in vitro replicates:

2

Details on study design:

SELECTION AND PREPARATION OF ISOLATED EYES
Selection; After removing the head from the plastic box, it was put on soft paper. The eyelids were carefully cut away with scissors, avoiding damaging the cornea. One small drop of 2% (w/v) fluorescein solution was applied onto the cornea surface for a few seconds and subsequently rinsed off with 20 mL physiological saline. The fluorescein-treated cornea was then examined with a hand-held slit lamp or slit lamp microscope, with the eye in the head, to ensure that the cornea was not damaged. If the cornea was undamaged and in good condition, the eyeball was carefully removed from the orbit.
Preparation; The eye ball was carefully removed from the orbit by holding the nictitating membrane with surgical forceps while cutting the eye muscles with bent scissors. Care was taken to remove the eyeball from the orbit without cutting the optic nerve too short. The procedure avoided pressure on the eye while removing the eyeball from the orbit, in order to prevent distortion of the cornea and subsequent corneal opacity. Once removed from the orbit, the eye was placed onto damp paper and the nictitating membrane was cut away with other connective tissue. The prepared eyes were kept on the wet papers in a closed box so that the appropriate humidity was maintained.

EQUILIBRATION AND BASELINE RECORDINGS
Equilibration; The appropriate number of eyes was selected and after being placed in the superfusion apparatus. There they were examined again with the slit lamp microscope to ensure that they were in good condition. The focus was adjusted to clearly see the physiological saline flowing on the cornea surface. Eyes with a high baseline fluorescein staining (i.e., > 0.5) or corneal opacity score (i.e., > 0.5) were rejected. The cornea thickness was measured, any eye with cornea thickness deviating more than 10 % from the mean value for all eyes, or eyes that showed any other signs of damage, were rejected and replaced. If the selected eyes were appropriate for the test, acclimatization started and was conducted for approximately 45 to 60 minutes. The chambers of the superfusion apparatus were at controlled temperature (32±1.5°C) during the acclimatization and treatment periods.
Baseline; At the end of the acclimatization period, a zero reference measurement was recorded for cornea thickness and opacity to serve as a baseline (t=0) for each individual eye. The cornea thickness of the eyes should not change by more than 5% within the -45 min and the zero time-point. No changes in thickness (0.0%) were observed in the eyes in each experiment. Following the equilibration period, the fluorescein retention was measured. Baseline values were required to evaluate any potential test item related effect after treatment. All eyes were considered to be suitable for the assay.

NUMBER OF REPLICATES
2

NEGATIVE CONTROL USED
Name: Physiological saline (Salsol solution, 0.9% (w/v) NaCl)
Batch numbers: 70323Y05-1, 72034Y05-1
Manufacturer: B. Braun Pharmaceuticals SA
Expiry dates: 31 December 2019, 30 April 2020
Storage condition: Room temperature


SOLVENT CONTROL USED (if applicable)

POSITIVE CONTROL USED
Name: Imidazole
CAS Number: 288-32-4
Manufacturer: Sigma-Aldrich Co.
Batch number: SLBK9670V
Expiry date: 30 November 2017
Storage conditions: Room temperature

APPLICATION DOSE AND EXPOSURE TIME
30mg for 10 seconds

OBSERVATION PERIOD
The control eyes and test eyes were evaluated pre-treatment and at approximately 30, 75, 120, 180 and 240 minutes after the post-treatment rinse. Minor variations within approximately ±5 minutes were considered acceptable.

REMOVAL OF TEST SUBSTANCE
- Volume and washing procedure after exposure period: the cornea surface was rinsed thoroughly with 20 mL physiological saline solution at ambient temperature,
- Indicate any deviation from test procedure in the Guideline
No data

METHODS FOR MEASURED ENDPOINTS:
- Corneal opacity:
Cornea opacity was calculated according to the following formulae:


ΔCO at time t = CO at time t – CO at t=0

Mean ΔCOmax = FECOmax(30min to 240min)+ SECOmax(30min to 240min)3 + TECOmax(30min to 240min)

- Damage to epithelium based on fluorescein retention:
Fluorescein retention was calculated according to the following formulae:


ΔFR at time t = FR at time t – FR at t=0

Mean ΔFR = FEFR (30min) + SEFR3(30 min) + TEFR(30min)

- Swelling: measured with optical pachymeter on a slit-lamp microscope; slit-width setting:
- Macroscopic morphological damage to the surface:
- Others (e.g, histopathology):

SCORING SYSTEM:
- Mean corneal swelling (%) ; 1.5%
mean maximum opacity score ; 0.42
- Mean fluorescein retention score at 30 minutes post-treatment ; 0.5

DECISION CRITERIA: please specify if the decision criteria as indicated in the TG was used. No data

Results and discussion

In vitro

Results

Results 1

Irritation parameter:

cornea opacity score

Run / experiment:

1

Value:

0.33

Vehicle controls validity:

not applicable

Negative controls validity:

valid

Positive controls validity:

valid

Remarks on result:

no indication of irritation

Results 2

Irritation parameter:

cornea opacity score

Run / experiment:

2

Value:

0.5

Vehicle controls validity:

not applicable

Negative controls validity:

valid

Positive controls validity:

valid

Remarks on result:

no indication of irritation

Results 3

Irritation parameter:

fluorescein retention score

Run / experiment:

1

Value:

0.5

Vehicle controls validity:

not applicable

Negative controls validity:

valid

Positive controls validity:

valid

Remarks on result:

no indication of irritation

Results 4

Irritation parameter:

fluorescein retention score

Run / experiment:

2

Value:

0.5

Vehicle controls validity:

not applicable

Negative controls validity:

valid

Positive controls validity:

valid

Remarks on result:

no indication of irritation

Results 5

Irritation parameter:

percent corneal swelling

Remarks:

up to 75 minutes.

Run / experiment:

1

Value:

1.6

Vehicle controls validity:

not applicable

Negative controls validity:

valid

Positive controls validity:

valid

Remarks on result:

no indication of irritation

Results 6

Irritation parameter:

percent corneal swelling

Remarks:

up to 240 minutes

Run / experiment:

1

Value:

1.6

Vehicle controls validity:

not applicable

Negative controls validity:

valid

Positive controls validity:

valid

Remarks on result:

no indication of irritation

Results 7

Irritation parameter:

percent corneal swelling

Remarks:

up to 75 minutes

Run / experiment:

2

Value:

0.5

Vehicle controls validity:

not applicable

Negative controls validity:

valid

Positive controls validity:

valid

Remarks on result:

no indication of irritation

Results 8

Irritation parameter:

percent corneal swelling

Remarks:

up to 240 minutes

Run / experiment:

2

Value:

2.2

Vehicle controls validity:

not applicable

Negative controls validity:

valid

Positive controls validity:

valid

Remarks on result:

no indication of irritation

Other effects / acceptance of results:

OTHER EFFECTS:
- Visible damage on test system: none

DEMONSTRATION OF TECHNICAL PROFICIENCY:

ACCEPTANCE OF RESULTS:
- Acceptance criteria met for negative control: yes
- Acceptance criteria met for positive control: yes
- Range of historical values if different from the ones specified in the test guideline: none

Applicant's summary and conclusion

Interpretation of results:

GHS criteria not met

Conclusions:

The test item p-toluic acid showed no significant corneal effect in the first experiment. As the test item was solid, the negative results were confirmed by a second experiment according to the recommendations of OECD guideline No. 438. The second experiment confirmed the negative results. Therefore, based on these in vitro eye irritation tests in isolated chicken eyes with p-toluic acid, the test item was non-irritant, UN GHS Classification: No Category.