4,4'-isopropylidenedi-o-cresol

Eye irritation

Administrative data

Endpoint:

eye irritation: in vitro / ex vivo

Type of information:

experimental study

Adequacy of study:

key study

Study period:

16 - 17 Sep 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 437 (Bovine Corneal Opacity and Permeability Test Method for Identifying i) Chemicals Inducing Serious Eye Damage and ii) Chemicals Not Requiring Classification for Eye Irritation or Serious Eye Damage)

Version / remarks:

adopted in Oct 2017

Deviations:

no

GLP compliance:

yes (incl. QA statement)

Remarks:

Government of India, Department of Science and Technology, India

Test material

Test material information

Constituent 1

Reference substance name:

4,4'-isopropylidenedi-o-cresol

EC Number:

201-240-0

EC Name:

4,4'-isopropylidenedi-o-cresol

Cas Number:

79-97-0

Molecular formula:

C17H20O2

IUPAC Name:

4,4'-isopropylidenedi-o-cresol

Test system

Vehicle:

other: corn oil

Remarks:

The test substance was insoluble in saline, therefore a homogenous suspension of the test substance in corn oil was prepared.

Controls:

yes, concurrent vehicle

yes, concurrent positive control

Amount / concentration applied:

TEST MATERIAL
- Amount(s) applied: 750 µL
- Concentration: 20% suspension (w/v) in corn oil

VEHICLE
- Amount(s) applied: 750 µL

POSITIVE CONTROL: Imidazole
- Amount(s) applied: 750 μL
- Concentration: 20% (w/v) in 0.9% sodium chloride solution

Duration of treatment / exposure:

4 h ± 5 min at 32 ± 1 °C

Duration of post- treatment incubation (in vitro):

90 ± 5 min at 32 ± 1 °C

Number of animals or in vitro replicates:

Triplicates for each treatment and control group

Details on study design:

SELECTION AND PREPARATION OF CORNEAS
The eyes were dissected with a 2 to 3 mm rim and were transferred to container containing Hank`s Blanced Salt Solution. Each cornea was mounted in a specially designed cornea holder.

QUALITY CHECK OF THE ISOLATED CORNEAS
Only corneas which were free from defects were used. The baseline opacity was determined for each cornea. Any corneas with opacity values >7 opacity units were discarded.

TREATMENT METHOD
Each cornea was mounted in a cornea holder with the endothelial side against the O-ring of the posterior part of the holder. Afterwards, the anterior part of the holder was positioned on top of the cornea and fixed in place with screws. Both compartments of the holder were filled with incubation medium, ensuring that no bubbles were present within the holders. For equilibration, the corneas in the holder were incubated in at 32 ± 1 °C for at least 1 h.

REMOVAL OF TEST SUBSTANCE
- Number of washing steps after exposure period: washing was performed until no visual evidence of the test substance was observed using medium with phenol red and thereafter using medium without phenol red.

METHODS FOR MEASURED ENDPOINTS:
- Corneal opacity: The light transmission through the corneas, given as lux value, was recorded and thereafter converted into an opacity value (baseline opacity values).
- Corneal permeability: The amount of fluorescein that crossed the cornea was measured spectrophotometrically (OD490) in the medium from the posterior chamber.

SCORING SYSTEM: In Vitro Irritancy Score (IVIS)

DECISION CRITERIA
Test substance with an IVIS > 55 was regarded as Category 1.
Test substance with an IVIS ≤ 3 was regarded as No Category.
Test substance with an IVIS > 3; ≤ 55: no prediction can be made.

Results and discussion

In vitro

Results

Irritation parameter:

in vitro irritation score

Run / experiment:

mean value of 3 corneae

Value:

3.54

Vehicle controls validity:

valid

Negative controls validity:

not applicable

Positive controls validity:

valid

Other effects / acceptance of results:

ACCEPTANCE OF RESULTS:
- Acceptance criteria met for negative control: After treatment with the vehicle control (corn oil) the calculated IVIS was 0.48, and therefore within two standard deviations of the reported historical mean of the negative control (IVIS: 0.09 - 1.48).
- Acceptance criteria met for positive control: After treatment with the positive control (20% imidazole) the calculated IVIS was 120.52 and, therefore within two standard deviations of the reported historical mean of the positive control (IVIS 63.28 - 257.23).

Applicant's summary and conclusion

Interpretation of results:

other: non-corrosive (Eye Irrit. 2 or not classified according to Regulation (EC) No 1272/2008)

Conclusions:

Under the conditions of the test, the test substance was shown to have no corrosive potential in the Bovine corneal opacity and permeability (BCOP) test prediction model. The result does not allow for the non-classification or classification as irritant of the test substance and therefore further evaluation and/or data generation is required.