4-(cyclohex-1-en-1-yl)-3-methylbutan-1-ol

Eye irritation

Administrative data

Endpoint:

eye irritation: in vitro / ex vivo

Type of information:

experimental study

Adequacy of study:

key study

Reliability:

1 (reliable without restriction)

Rationale for reliability incl. deficiencies:

guideline study

Data source

Reference

Reference Type:

study report

Title:

Unnamed

Year:

2014

Report date:

2014

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 i) Chemicals Inducing Serious Eye Damage and ii) Chemicals Not Requiring Classification for Eye Irritation or Serious Eye Damage)

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)

GLP compliance:

yes

Test material

Test material information

Constituent 1

Reference substance name:

4-(cyclohex-1-en-1-yl)-3-methylbutan-1-ol

EC Number:

806-826-5

Cas Number:

1359994-45-8

Molecular formula:

C11H20O

IUPAC Name:

4-(cyclohex-1-en-1-yl)-3-methylbutan-1-ol

Test material form:

liquid

Specific details on test material used for the study:

- Test substance storage In refrigerator (2-8°C) in the dark
- Description: Clear colourless liquid
- Expiry date: 19 March 2015

Test animals / tissue source

Details on test animals or tissues and environmental conditions:

SOURCE OF COLLECTED EYES
- Source: Bovine eyes from young cattle were obtained from the slaughterhouse (Vitelco, 's Hertogenbosch, The Netherlands), where the eyes were excised by a slaughterhouse employee as soon as possible after slaughter.
- Storage, temperature and transport conditions of ocular tissue (e.g. transport time, transport media and temperature, and other conditions): Eyes were collected and transported in physiological saline in a suitable container under cooled conditions.
- indication of any existing defects or lesions in ocular tissue samples: The eyes were checked for unacceptable defects, such as opacity, scratches, pigmentation and neovascularization by removing them from the physiological saline and holding them in the light. Those exhibiting defects were discarded.

Test system

Vehicle:

unchanged (no vehicle)

Details on study design:

SELECTION AND PREPARATION OF CORNEAS
The isolated corneas were stored in a petri dish with cMEM (Eagle’s Minimum Essential Medium (Invitrogen Corporation, Breda, The Netherlands) containing 1% (v/v) L-glutamine (Invitrogen Corporation) and 1% (v/v) Foetal Bovine Serum (Invitrogen Corporation)). The isolated corneas were mounted in a corneal holder (one cornea per holder) of MC2 (Clermont, France) with the endothelial side against the O-ring of the posterior half of the holder. The anterior half of the holder was positioned on top of the cornea and tightened with screws. The compartments of the corneal holder were filled with cMEM of 32±1°C. The corneas were incubated for the minimum of 1 hour at 32±1°C. After the incubation period, the medium was removed from both compartments and replaced with fresh cMEM. Opacity determinations were performed on each of the corneas using an opacitometer (OP-KIT, MC2, Clermont, France). The opacity of each cornea was read against an air filled chamber, and the initial opacity reading thus determined was recorded. Corneas that had an initial opacity reading higher than 7 were not used.

NUMBER OF REPLICATES
Three corneas were selected at random for each treatment group.

NEGATIVE CONTROL USED
A negative control, physiological saline (Eurovet Animal Health, Bladel, The Netherlands) was included to detect non-specific changes in the test system and to provide a baseline for the assay endpoints.

POSITIVE CONTROL USED
10% (w/v) Benzalkonium Chloride (Sigma-Aldrich Chemie GmbH, Germany) [CAS Number 63449-41- 2] solution prepared in physiological saline.

TREATMENT METHOD:
The medium from the anterior compartment was removed and 750 µL of either the negative control, positive control (10% (w/v) Benzalkonium Chloride) or test substance was introduced onto the epithelium of the cornea. The holders were slightly rotated, with the corneas maintained in a horizontal position, to ensure uniform distribution of the control or the test substance over the entire cornea. Corneas were incubated in a horizontal position for 10±1 minutes at 32±1°C. After the incubation the solutions were removed and the epithelium was washed with MEM with phenol red (Eagle’s Minimum Essential Medium, Invitrogen Corporation) and thereafter with cMEM. Possible pH effects of the test substance on the corneas were recorded. The medium in the posterior compartment was removed and both compartments were refilled with fresh cMEM. Subsequently the corneas were incubated for 120±10 minutes at 32±1°C. After the completion of the incubation period opacity determination was performed. Each cornea was inspected visually for dissimilar opacity patterns.

METHODS FOR MEASURED ENDPOINTS:
- Opacity measurement: The opacitometer determined the difference in the light transmission between each control or treated cornea and an air filled chamber. The numerical opacity value (arbitrary unit) was displayed and recorded. The change in opacity for each individual cornea (including the negative control) was calculated by subtracting the initial opacity reading from the final post-treatment reading. The corrected opacity for each positive control or test substance treated cornea was calculated by subtracting the average change in opacity of the negative control corneas from the change in opacity of each positive control or test substance treated cornea. The mean opacity value of each treatment group was calculated by averaging the corrected opacity values of the treated corneas for each treatment group.
- Application of sodium fluorescein: Following the final opacity measurement, permeability of the cornea to Na-fluorescein (Merck, Darmstadt, Germany) was evaluated. The medium of both compartments (anterior compartment first) was removed. The posterior compartment was refilled with fresh cMEM. The anterior compartment was filled with 1 ml of 4 mg Na-fluorescein/ml cMEM solution. The holders were slightly rotated, with the corneas maintained in a horizontal position, to ensure uniform distribution of the sodium-fluorescein solution over the entire cornea. Corneas were incubated in a horizontal position for 90±5 minutes at 32±1°C.
- Permeability determinations: After the incubation period, the medium in the posterior compartment of each holder was removed and placed into a sampling tube labelled according to holder number. 360 µl of the medium from each sampling tube was transferred to a 96-well plate. The optical density at 490 nm (OD490) of each sampling tube was measured in triplicate using a microplate reader (TECAN Infinite® M200 Pro Plate Reader). Any OD490 that was 1.500 or higher was diluted to bring the OD490 into the acceptable range (linearity up to OD490 of 1.500 was verified before the start of the experiment). OD490 values of less than 1.500 were used in the permeability calculation. The mean OD490 for each treatment was calculated using cMEM corrected OD490 values. If a dilution was performed, the OD490 of each reading was corrected for the mean negative control OD490 before the dilution factor was applied to the readings.

SCORING SYSTEM: In Vitro Irritancy Score (IVIS)

DECISION CRITERIA:
- In vitro irritancy score: The mean opacity and mean permeability values (OD490) were used for each treatment group to calculate an in vitro score: In vitro irritancy score (IVIS) = mean opacity value + (15 x mean OD490 value). Additionally the opacity and permeability values were evaluated independently to determine whether the test substance induced irritation through only one of the two endpoints. The IVIS cut-off values for identifying the test substances as inducing eye damage (UN GHS
Category 1) and test substances not requiring classification for eye irritation or serious eye damage (UN GHS No Category) are: ≤3: No category/Non irritant; >3; ≤55: No prediction can be made/Mild to moderate irritant; >55: Category 1/Severe irritant
- Acceptability of the assay: The assay is considered acceptable if: The positive control gives an in vitro irritancy score that falls within the laboratory historical mean value and the negative control responses should result in opacity and permeability values that are less than the upper limits of the laboratory historical range.

Results and discussion

In vitro

Results

Irritation parameter:

in vitro irritation score

Value:

7.8

Vehicle controls validity:

not applicable

Negative controls validity:

valid

Positive controls validity:

valid

Other effects / acceptance of results:

The individual in vitro irritancy scores for the negative controls ranged between -0.1 and 0.1. The individual positive control in vitro irritancy scores ranged from 112 to 166 for Benzalkonium Chloride. The corneas treated with the positive control substance were turbid after the 10 minutes of treatment. The corneas treated with the test substance showed opacity values ranging from 5 to 6 and permeability values ranging from 0.091 to 0.237. The corneas were turbid with stripes after the 10 minutes of treatment with the test substance. No pH effect of the test substance was observed on the rinsing medium. Hence, the in vitro irritancy scores ranged from 6.4 to 9.6 after 10 minutes of treatment with the test substance.

Applicant's summary and conclusion

Interpretation of results:

Category 2 (irritating to eyes) based on GHS criteria