2-Cyclohexen-1-one, 2-methyl-5-propyl-

Eye irritation

Administrative data

Endpoint:

eye irritation: in vitro / ex vivo

Type of information:

experimental study

Adequacy of study:

key study

Study period:

2013-12-06

Reliability:

1 (reliable without restriction)

Rationale for reliability incl. deficiencies:

other: GLP 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 Ocular Corrosives and Severe Irritants)

Version / remarks:

adopted 2013-07-26

Deviations:

yes

Remarks:

please refer to the field "Rationale for reliability incl. deficiencies" above

Test guideline 2

Qualifier:

according to guideline

Guideline:

other: Bovine Corneal Opacity and Permeability (BCOP) Assay, SOP of Microbiological Associates Ltd., UK, Procedure Details, April 1997

GLP compliance:

yes (incl. QA statement)

Remarks:

signed 2013-04-11

Test material

Test material information

Constituent 1

Reference substance name:

2-methyl-5-propylcyclohex-2-en-1-one

EC Number:

807-489-7

Cas Number:

1447712-18-6

Molecular formula:

C10H16O1

IUPAC Name:

2-methyl-5-propylcyclohex-2-en-1-one

Test material form:

other: liquid

Details on test material:

- Physical state: liquid, clear pale yellow
- Storage condition of test material: at room temperature

Test animals / tissue source

Details on test animals or tissues and environmental conditions:

Not applicable - Since this is an in vitro study there is no information on test animals.

Test system

Vehicle:

unchanged (no vehicle)

Controls:

other: Control (saline) bovine corneae were used.

Amount / concentration applied:

TEST MATERIAL
- Amount(s) applied (volume or weight with unit): 0.75 mL of the test item

Duration of treatment / exposure:

10 minutes

Observation period (in vivo):

not applicable

Number of animals or in vitro replicates:

Number of bovine corneae per dose:
Test item: triplicates
Negative control: triplicates
Positive control: triplicates

Details on study design:

COLLECTION OF BOVINE EYES
- isolated bovine eyes of at least 9 month old donor cattle were collected from the abattoir and were transported in Hank's buffered salt solution (HBSS) supplemented with streptomycin / penicillin at ambient temperature.

PREPARATION OF CORNEAE
- all eyes were carefully examined macroscopically for defects.
- the cornea was carefully removed from the eye.
- each cornea was mounted in a specially designed cornea holder according to the description given in OEDC guideline 437, annex III, that consists of anterior and posterior compartments, which interface with the epithelial and endothelial sides of the cornea, respectively. Both compartments of the holder were filled with incubation medium.
- 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.
- at the end of the incubation period, the basal opacity was determined (t0) of all cornea.
- each corneae with a value of the basal opacity > 7 was discarded.

EXPOSURE OF THE TEST GROUPS TO THE CORNEAE
- the anterior compartment received the undiluted test item or negative control (saline) or positive control (2-Ethoxyethanol; tested neat) at a volume of 0.75 mL on the surface of the corneae.
- the corneae were incubated in a horizontal position at 32 ± 1 °C in the water-bath (incubation time: 10 minutes).
- the test item, positive control and negatice control were tested in triplicate.
- the test item or control items were rinsed off with saline.
- the corneae were then incubated at 32 ± 1 °C for further two hours in a vertical position, followed by a second opacity reading (t130).
- permeability of the corneae was determined.

PERMEABILITY MEASUREMENT
- after the final opacity measurement, the complete medium was removed from the anterior compartment and replaced by 0.5% (w/v) sodium fluorescein solution in HBSS.
- corneae were incubated in a horizontal position for 90 minutes in a water-bath at 32 ± 1 °C.
- complete medium from the posterior compartment was removed, well mixed and the optical density at 490 nm was determined with a spectrophotometer (software SoftMax Pro Enterprise, version 4.7.1).

EVALUATION OF RESULTS
- Opacity: the change of opacity value of each treated cornea or positive and negative control corneae is calculated by subtracting the initial basal opacity from the post treatment opacity reading (t130 – t0), for each individual cornea.
The average change in opacity of the negative control corneae is calculated and this value is subtracted from the change in opacity of each treated cornea or positive control to obtain a corrected opacity.
- Permeability: the corrected OD490 value of each cornea treated with positive control and test item is calculated by subtracting the average negative control cornea value from the original permeability value for each cornea.

IN VITRO IRRITATION SCORE CALCULATION
The following formula was used to determine the in vitro irritation score (IVIS) of the negative control:
In vitro Irritation Score = opacity value + (15 x OD490 value)
The following formula was used to determine the in vitro irritation score of the positive control and the test item:
In vitro Irritation Score = (opacity value – opacity value mean negative control) + (15 x corrected OD490 value)
The mean IVIS value of each treated group was calculated from the IVIS values.
Depending on the score obtained, the test item was classified into the following category according to OECD 437 (table 1 in the field "Any other information on materials and methods incl. tables" below).

CRITERIA FOR DETERMINATION OF A VALID TEST
The test was acceptable if
- the positive control gives an IVIS that falls within two standard deviations of the current historical mean, and if
- the negative control responses result in opacity and permeability values that are less than the established upper limits for background opacity and permeability values for bovine corneae treated with the respective negative control.

Results and discussion

In vivo

Results

Irritation parameter:

other: in vitro irritancy score

Basis:

mean

Time point:

other: 10 minutes

Score:

2.84

Irritant / corrosive response data:

Relative to the negative control, the test item caused slight opacity but no permeability on the corneae. The calculated mean IVIS was 2.84.

Any other information on results incl. tables

Table 1: Results after 10 minutes incubation time

Test group	Opacity value = Difference (t130 – t0) of opacity		Permeability at 490 nm (OD490)		In vitro irritancy score	Mean in vitro irritancy score
		Mean		Mean
Negative control	0	0.00	0.044	0.043	0.66	0.65
	0		0.043		0.65
	0		0.042		0.63
Positive control	58.00		0.600*		67.00	58.49
	45.00		0.432*		51.48
	48.00		0.599*		56.99
Test item	1.00		0.001*		1.02	2.84
	4.00		0.025*		4.38
	2.00		0.075*		3.13

* corrected values

- With the negative control (saline) neither an increase of opacity nor permeability of the corneae could be observed (mean IVIS= 0.65).

- The positive control (2-Ethoxyethanol) showed clear opacity and distinctive permeability of the corneae (mean IVIS =58.49).

Table 2: Historical data

	Positive control	Negative control
Mean IVIS	72.74	1.13
Standard deviation	18.79	0.77
Range of IVIS	33.59 – 153.20	0.00 – 2.84

Values of 190 studies with solid test items performed from February 2007 until November 2013

Applicant's summary and conclusion

Interpretation of results:

not irritating

Remarks:

Migrated information Criteria used for interpretation of results: EU

Conclusions:

Relative to the negative control, the test item caused a very slight increase of the corneal opacity. Permeability effects did not occur. In conclusion, according to the current study and under the experimental conditions reported, the test item is not irritating to the eye (the calculated IVIS = 2.84). According to OECD 437 (adopted July, 26th 2013) a chemical that induces an IVIS≤ 3 is considered as not requiring classification for eye irritation or serious eye damage.

Executive summary:

In this in vitro study the test substance was tested for its eye irritation potential according to the OECD guideline 437 (2013) using fresh bovine corneae. Three corneae were exposed to either the undiluted test item (0.75 mL), the positive control (2 -Ethoxyethanol (neat); 0.75 mL), or the negative control (saline; 0.75 mL) for 10 minutes (incubation temperature: 32 ± 1 °C). After the incubation phase the test item, the positive control, and the negative control were each rinsed from the corneae. Further, the corneae were incubated for another 120 minutes at 32 ± 1 °C in incubation medium. Next, the corneal opacity and permeability were measured and the In vitro Irritancy Score (IVIS) was calculated for the test item and the controls.

Relative to the negative control, the test item caused slight opacity but no permeability on the corneae. The calculated mean IVIS was 2.84 (threshold for serious eye damage: IVIS≥ 55. According to OECD 437 (adopted July, 26th 2013) a chemical that induces an IVIS≤ 3 is considered as not requiring classification for eye irritation or serious eye damage.