2-ethylhexyl 7-oxabicyclo[4.1.0]heptane-3-carboxylate

Eye irritation

Administrative data

Endpoint:

eye irritation: in vitro / ex vivo

Type of information:

experimental study

Adequacy of study:

key study

Study period:

2017

Reliability:

1 (reliable without restriction)

Rationale for reliability incl. deficiencies:

guideline study

Data source

Reference

Reference Type:

study report

Title:

Unnamed

Year:

2018

Report date:

2018

Materials and methods

Test guideline

Test guideline 1

Qualifier:

according to guideline

Guideline:

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

Deviations:

no

Test guideline 2

Qualifier:

according to guideline

Guideline:

EU method B.47 (Bovine corneal opacity and permeability test method for identifying ocular corrosives and severe irritants)

Deviations:

no

GLP compliance:

yes

Test material

Test material information

Constituent 1

Reference substance name:

2-ethylhexyl 7-oxabicyclo[4.1.0]heptane-3-carboxylate

EC Number:

263-471-3

EC Name:

2-ethylhexyl 7-oxabicyclo[4.1.0]heptane-3-carboxylate

Cas Number:

62256-00-2

Molecular formula:

C15H26O3

IUPAC Name:

2-ethylhexyl 7-oxabicyclo[4.1.0]heptane-3-carboxylate

Specific details on test material used for the study:

Batch: AH03201
Purity: 100%
Physical state/Appearance: clear colorless liquid
Expiry Date: 01 February 2019
Storage Conditions: approximately 4o C in the dark

Test animals / tissue source

Species:

cattle

Strain:

not specified

Details on test animals or tissues and environmental conditions:

Eyes from adult cattle (typically 12 to 60 months old) were obtained from a local abattoir as a by-product from freshly slaughtered animals. The eyes were excised by an abattoir employee after slaughter, and were placed in Hanks’ Balanced Salt Solution (HBSS) supplemented with antibiotics (penicillin at 100 IU/mL and streptomycin at 100 μg/mL). They were transported to the test facility over ice packs on the same day of slaughter. The corneas were refrigerated on arrival and used within 24 hours of receipt.

Test system

Controls:

yes, concurrent positive control

yes, concurrent negative control

Amount / concentration applied:

The undiluted test item was applied for 10 minutes followed by an incubation period of 120 minutes.

Duration of treatment / exposure:

Treatment of Corneas

The EMEM (Eagle’s Minimum Essential Medium) was removed from the anterior chamber of the BCOP holder and 0.75 mL of the test item or control items were applied to the appropriate corneas. The holders were gently tilted back and forth to ensure a uniform application of the item over the entire cornea. Each holder was incubated, anterior chamber uppermost, at 32 ± 1 ºC for 10 minutes.

At the end of the exposure period the test item and control items were removed from the anterior chamber and the cornea was rinsed three times with fresh complete EMEM containing phenol red before a final rinse with complete EMEM without phenol red. The anterior chamber was refilled with fresh complete EMEM without phenol red. A post-treatment opacity reading was taken and each cornea was visually observed.
The holders were incubated, anterior chamber facing forward, at 32 ± 1 ºC for 120 minutes.After incubation the holders were removed from the incubator, the medium from both chambers was replaced with fresh complete EMEM and a final opacity reading was taken. Each cornea was visually observed.

Number of animals or in vitro replicates:

Three

Details on study design:

Preparation of Corneas

All eyes were macroscopically examined before and after dissection. Only corneas free of damage were used.The cornea from each selected eye was removed leaving a 2 to 3 mm rim of sclera to facilitate handling. The iris and lens were peeled away from the cornea. The isolated corneas were immersed in a dish containing HBSS until they were mounted in Bovine Corneal Opacity and Permeability (BCOP) holders.The anterior and posterior chambers of each BCOP holder were filled with complete Eagle’s Minimum Essential Medium (EMEM) without phenol red and plugged. The holders were incubated at 32 ± 1 ºC for 60 minutes. At the end of the incubation period each cornea was examined for defects. Only corneas free of damage were used.

Selection of Corneas and Opacity Reading
Three corneas with opacity values close to the median value of all corneas were allocated to the negative control. Three corneas were also allocated to the test item and three corneas to the positive control item.

Treatment of Corneas
The EMEM (Eagle’s Minimum Essential Medium) was removed from the anterior chamber of the BCOP holder and 0.75 mL of the test item or control items were applied to the appropriate corneas. The holders were gently tilted back and forth to ensure a uniform application of the item over the entire cornea. Each holder was incubated, anterior chamber uppermost, at 32 ± 1 ºC for 10 minutes.The holders were incubated, anterior chamber facing forward, at 32 ± 1 ºC for 120 minutes

Application of Sodium Fluorescein
Following the final opacity measurement the permeability of the corneas to sodium fluorescein was evaluated. The medium from the anterior chamber was removed and replaced with 1 mL of sodium fluorescein solution (4 mg/mL). The dosing holes were plugged and the holders incubated, anterior chamber uppermost, at 32 ± 1 ºC for 90 minutes

Permeability Determinations
After incubation the medium in the posterior chamber of each holder was decanted and retained.
360 μL of media representing each cornea was dispensed into the appropriate wells of a pre-labeled 96-well plate. The optical density was measured (quantitative viability analysis) at 492 nm (without a reference filter) using the Labtech LT-4500 microplate reader.

Histopathology
The corneas were retained after testing for possible conduct of histopathology

Data Evaluation
Results from the two test method endpoints, opacity and permeability, were combined in an empirically derived formula to generate an In Vitro Irritancy Score.

Results and discussion

In vitro

Results

Irritation parameter:

in vitro irritation score

Value:

0.7

Negative controls validity:

valid

Remarks:

Gave Irritancy Score of 0.4

Positive controls validity:

valid

Remarks:

Gave Irritancy Score of 42.1

Applicant's summary and conclusion

Interpretation of results:

other: No category. Not requiring classification to UN GHS or EU CLP.

Remarks:

No category. Not requiring classification to UN GHS or EU CLP.

Conclusions:

No category. Not requiring classification to UN GHS or EU CLP.

Executive summary:

An in vitro BCOP test was conducted to identify test item that can induce serious eye damage and to identify test items not requiring classification for eye irritation or serious eye damage. The Bovine Corneal Opacity and Permeability (BCOP) test method is an organotypic model that provides short-term maintenance of normal physiological and biochemical function of the bovine cornea in vitro. The undiluted test item was applied for 10 minutes followed by an incubation period of 120 minutes. Negative and positive control items were tested concurrently. The two endpoints, decreased light transmission through the cornea (opacity) and increased passage of sodium fluorescein dye through the cornea (permeability) were combined in an empirically derived formula to generate an In Vitro Irritancy Score (IVIS). The In Vitro irritancy scores reported as 0.7 for 2-ethylhexyl 7-oxabicyclo [4.1.0] heptane-3-carboxylate and 0.4 and 42.1 for negative and positive control. Based on irritancy score the test item is not classified as eye irritant. The test item is not requiring classification to UN GHS or EU CLP.