4-methoxybenzyl alcohol

Eye irritation

Administrative data

Endpoint:

eye irritation: in vitro / ex vivo

Type of information:

experimental study

Adequacy of study:

weight of evidence

Study period:

February 2016 and August 2016

Reliability:

1 (reliable without restriction)

Rationale for reliability incl. deficiencies:

guideline study

Data source

Reference

Reference Type:

study report

Title:

Unnamed

Year:

2016

Report date:

2016

Materials and methods

Test guideline

Qualifier:

according to guideline

Guideline:

OECD Guideline 437 (Bovine Corneal Opacity and Permeability Test Method for Identifying Ocular Corrosives and Severe Irritants)

Version / remarks:

July 2013

Deviations:

no

GLP compliance:

yes (incl. QA statement)

Test material

Test material information

Constituent 1

Reference substance name:

4-methoxybenzyl alcohol

EC Number:

203-273-6

EC Name:

4-methoxybenzyl alcohol

Cas Number:

105-13-5

Molecular formula:

C8H10O2

IUPAC Name:

(4-methoxyphenyl)methanol

Test animals / tissue source

Species:

other: isolated bovine cornea

Details on test animals or tissues and environmental conditions:

SOURCE OF COLLECTED EYES
- Characteristics of donor animals: at least 9 months old
- Storage, temperature and transport conditions of ocular tissue: at ambient temperature
- Time interval prior to initiating testing: The corneae were isolated on the same day after delivery of the eyes. The corneae were directly used in the BCOP test on the same day.
- indication of any existing defects or lesions in ocular tissue samples: Eyes presenting defects such as vascularization, pigmentation, opacity and scratches were discarded.

Test system

Vehicle:

unchanged (no vehicle)

Controls:

yes, concurrent positive control

yes, concurrent negative control

Amount / concentration applied:

TEST MATERIAL
- Amount applied: 0.75 mL

Duration of treatment / exposure:

10 min

Duration of post- treatment incubation (in vitro):

2 hours

Number of animals or in vitro replicates:

3 corneas per group

Details on study design:

SELECTION AND PREPARATION OF CORNEAS
The cornea was carefully removed from the eye using scalpel and rounded scissors. A rim of about 2 mm of tissue (sclera) was left for stability and handling of the isolated cornea. Each isolated cornea was mounted in a specially designed cornea holder according to the description given in OECD guideline 437, that consists of anterior and posterior compartments, which interface with the epithelial and endothelial sides of the cornea, respectively. The endothelial side of the cornea was positioned against the sealing ring (Oring) of the posterior part of the holder. The cornea was gently flattened over the O-ring but stretching was avoided. 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. The posterior compartment was filled first to return the cornea to its natural convex position. Care was taken to assure no air bubbles were present within the compartments. For equilibration, the corneae in the holder were incubated in a vertical position for about one hour at 32 ± 1 °C in a water-bath. Sets of three corneae were used for treatment with the test item and the negative and positive controls.

QUALITY CHECK OF THE ISOLATED CORNEAS
All eyes were carefully examined macroscopically for defects. Those presenting defects such as vascularization, pigmentation, opacity and scratches were discarded. At the end of the incubation period, the basal opacity was determined (t0). The basal opacity of all corneae was recorded. Each corneae with a value of the basal opacity > 7 was discarded.

NUMBER OF REPLICATES: 3

NEGATIVE CONTROL USED: Yes

POSITIVE CONTROL USED: Yes

APPLICATION DOSE AND EXPOSURE TIME: 0.75 mL and 10 min

POST-INCUBATION PERIOD: yes (2 hours)

REMOVAL OF TEST SUBSTANCE
- POST-EXPOSURE INCUBATION: 2 hours

METHODS FOR MEASURED ENDPOINTS:
- Corneal opacity: OP_KIT opacitometer (changes in the light transmission passing through the cornae)
- Corneal permeability: passage of sodium fluorescein dye measured with the aid of microtiter plate reader (OD490)

SCORING SYSTEM: In Vitro Irritancy Score (IVIS)

DECISION CRITERIA:
IVIS ≤ 3 No Category (according to GHS)
IVIS > 3; ≤ 55 No prediction can be made
IVIS > 55 Serious eye damage according to CLP/EPA/GHS (Cat 1)

Results and discussion

In vitro

Results

Results 1

Irritation parameter:

in vitro irritation score

Run / experiment:

1

Value:

12.04

Vehicle controls validity:

not examined

Negative controls validity:

valid

Positive controls validity:

valid

Results 2

Irritation parameter:

in vitro irritation score

Run / experiment:

2

Value:

16.37

Vehicle controls validity:

not examined

Negative controls validity:

valid

Positive controls validity:

valid

Results 3

Irritation parameter:

in vitro irritation score

Run / experiment:

3

Value:

13.95

Vehicle controls validity:

not examined

Negative controls validity:

valid

Positive controls validity:

valid

Other effects / acceptance of results:

ACCEPTANCE OF RESULTS:
- Acceptance criteria met for negative control: Neither an increase of opacity nor permeability of the cornae could be obsered. However the negative control values were slightly elevated beyond the historical control data of the negative control range (IVIS = 0.560 - 1.70). This elevation is caused by a single cornea, which had a slightly elevated IVIS value. Because the mean IVIS of the three negative control cornea is still below the threshold for categorization (< 3), this deviation is considered irrelevant.
- Acceptance criteria met for positive control: Yes

Applicant's summary and conclusion

Interpretation of results:

other: not Category 1 according to GHS criteria

Conclusions:

Based on the results of the OECD 437 study, the test item is not serious eye damaging (Cat. 1) but a prediction for the damage hazard cannot be made.

Executive summary:

To assess the corneal damage potential of the test item, an in vitro study according to OECD TG 437 was investigated. After a first opacity measurement of the fresh bovine cornea (t0), the neat test item, the positive control, and the negative control were applied to corneae fixed in an incubation chamber in horizontal position for 10 minutes at 32°C. After the incubation phase the test item, the positive control, and the negative controls were each rinsed from the cornea. Further, teh cornea were incubated for another 120 min at 32°C in a vertical position. Afterwards, opacity was measured a second time (t130). Permeability of the cornea was also determined after opacity measurements.

The acceptance criteria for the negative and positive control were met. Although, the negative values were slightly outside the historical control data range, which is caused by a single cornea and still below the threshold for categorization, this deviation is conidered irrelevant.

In comparison to the negative control, the test item caused an increase of the corneal opacity. The calculated mean in vitro irritancy score was 14.12. In conclusion, the test item is not classified as serious eye damaging but the test item's hazard for eye damaging cannot be predicted.