1-methoxyhexane

Eye irritation

Administrative data

Endpoint:

eye irritation: in vitro / ex vivo

Type of information:

experimental study

Adequacy of study:

key study

Study period:

05-12-2016 to 25-01-2017

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 438 (Isolated Chicken Eye Test Method for Identifying i) Chemicals Inducing Serious Eye Damage and ii) Chemicals Not Requiring Classification for Eye Irritation or Serious Eye Damage)

Deviations:

no

GLP compliance:

yes (incl. QA statement)

Remarks:

Triskelion B.V., Utrechtseweg 48, 3700 AV, Zeist

Test material

Test material information

Constituent 1

Reference substance name:

1-methoxyhexane

EC Number:

225-263-0

EC Name:

1-methoxyhexane

Cas Number:

4747-07-3

Molecular formula:

C7H16O

IUPAC Name:

1-methoxyhexane

Test material form:

liquid

Test animals / tissue source

Species:

other: Eyes of male or female chickens (ROSS, spring chickens)

Details on test animals or tissues and environmental conditions:

SOURCE OF COLLECTED EYES
- Source: Slaughterhouse v.d. Bor, Nijkerkerveen, The Netherlands
- Characteristics of donor animals: Approximately 7 weeks old, male or female chickens, body weight range approximately 1.5-2.5 kg, were used as eye donors.
- Storage, temperature and transport conditions of ocular tissue: Heads of the animals were cut off immediately after sedation of the animals by electric shock and incision of the neck for bleeding, and before they reached the next station on the process line. The heads were placed in small plastic boxes on a bedding of paper tissues moistened with isotonic saline. Next, they were transported to the testing facility. During transportation, the heads were kept at ambient temperature.
- Time interval prior to initiating testing: Within 2 hours after kill, eyes were carefully dissected and placed in a superfusion apparatus.
- Indication of any existing defects or lesions in ocular tissue samples: No
- Indication of any antibiotics used: No

Test system

Vehicle:

unchanged (no vehicle)

Details on study design:

SELECTION AND PREPARATION OF ISOLATED EYES
Within 2 hours after kill, eyes were carefully dissected and placed in a superfusion apparatus using the following procedure: First the eye-lids were carefully removed without damaging the cornea and a small drop of Fluorescein sodium 2.0% w/v was applied to the corneal surface for a few seconds and subsequently rinsed off with isotonic saline at ambient temperature. Next, the head with the fluorescein-treated cornea was examined with a slit-lamp microscope (Slit-lamp 900 BP, Haag-Streit AG, Liebefeld-Bern, Switzerland) to ensure that the cornea was not damaged. If undamaged (e.g., fluorescein retention and corneal opacity scores of ≤ 0.5), the eye was further dissected from the head without damaging the eye or cornea. Care was taken to remove the eye-ball from the orbit without cutting off the optical nerve too short. The enucleated eye was placed in a stainless steel clamp with the cornea positioned vertically and transferred to a chamber of the superfusion apparatus. The clamp holding the eye was positioned in such a way that the entire cornea was supplied with isotonic saline from a bent, stainless steel tube, at a target rate of 0.10-0.15 mL/min. The chambers of the superfusion apparatus as well as the saline were temperature controlled at approximately 32 °C (water pump set at 36.4 °C). After placing in the superfusion apparatus, the eyes were examined again with the slit-lamp microscope to ensure that they were not damaged. An accurate measurement was taken at the corneal apex of each eye. Eyes with a corneal thickness deviating more than 10% of the average corneal thickness of the eyes, eyes showing opacity (score higher than 0.5), or were unacceptably stained with fluorescein (score higher than 0.5) indicating the cornea to be permeable, or eyes that showed any other signs of damage, were rejected as test eyes and replaced.

EQUILIBRATION AND BASELINE RECORDINGS
Each eye provided its own baseline values for corneal swelling, corneal opacity and fluorescein retention. For that purpose, after an equilibration period of 45-60 minutes, the corneal thickness of the eyes was measured again to determine the zero reference value for corneal swelling calculations.

NUMBER OF REPLICATES
Negative control: 1
Positive control: 3
Test group: 3

NEGATIVE CONTROL USED
Physiological saline

POSITIVE CONTROL USED
Benzalkonium Chloride 5%

APPLICATION DOSE AND EXPOSURE TIME
30 μL for 10 seconds

OBSERVATION PERIOD
240 minutes

REMOVAL OF TEST SUBSTANCE
- Volume and washing procedure after exposure period: 20 mL saline. After rinsing, each eye in the holder was returned to its chamber.
- Indicate any deviation from test procedure in the Guideline: none

METHODS FOR MEASURED ENDPOINTS:
- Corneal opacity: Slit-lamp microscope examination
- Damage to epithelium based on fluorescein retention: Slit-lamp microscope examination
- Swelling: measured with optical pachymeter on a slit-lamp microscope; slit-width setting: set at 0.095 mm
- Others: After the final examination, the test substance treated eyes, the negative and positive control eyes were preserved in a neutral aqueous phosphate-buffered 4% solution of formaldehyde. The corneas were embedded in paraffin wax, sectioned at ca 4 μm and stained with PAS (Periodic Acid-Schiff). The microscopic slides were subjected to histopathological examination.

SCORING SYSTEM:
Defined scoring scales were used for each parameter to define the severity of effects into four categories (I-IV).
- Mean corneal swelling (%): According to OECD 438 guideline. Examination of the eyes after 0, 30, 75, 120, 180, and 240 minutes
- Mean maximum opacity score: According to OECD 438 guideline. Examination of the eyes after 0, 30, 75, 120, 180, and 240 minutes
- Mean fluorescein retention score at 30 minutes post-treatment: According to OECD 438 guideline.

DECISION CRITERIA: According to OECD 438 guideline

Results and discussion

In vitro

Results

Results 1

Irritation parameter:

percent corneal swelling

Run / experiment:

slit-lamp examination

Value:

1

Vehicle controls validity:

not applicable

Negative controls validity:

valid

Positive controls validity:

valid

Remarks on result:

other: maximum mean values

Results 2

Irritation parameter:

cornea opacity score

Run / experiment:

slit-lamp examination

Value:

0.8

Vehicle controls validity:

not applicable

Negative controls validity:

valid

Positive controls validity:

valid

Remarks on result:

other: maximum mean values

Results 3

Irritation parameter:

fluorescein retention score

Run / experiment:

slit-lamp examination

Value:

0.3

Vehicle controls validity:

not applicable

Negative controls validity:

valid

Positive controls validity:

valid

Other effects / acceptance of results:

Slit-lamp examination: The tested substance caused no or very slight corneal swelling (mean of 1%), very slight or slight opacity (mean of 0.8) and no or very slight fluorescein retention (mean score 0.3). The negative control eye did not show any corneal effect and demonstrated that the general conditions during the tests were adequate. The positive control BAC 5% caused severe corneal effects and demonstrated the ICE test valid to detect severe eye irritants.

Microscopic examination of the corneas treated with the test substance revealed very slight erosion and very slight vacuolation of the epithelium in two corneas. Microscopic examination of the cornea treated with the negative control (saline) did not reveal any abnormalities. Microscopic examination of the corneas treated with the positive control BAC 5% revealed severe erosion and slight vacuolation of the epithelium, the epithelium partly detached from the basement membrane (two corneas), and endothelial necrosis (two corneas).

Applicant's summary and conclusion

Interpretation of results:

other: Not irritating

Remarks:

According to EU CLP 1272/2008 and its amendments.

Conclusions:

Under the test conditions (OECD 438 and GLP) the test substance is not considered to be an eye irritant.

Executive summary:

In accordance to OECD guideline 438 and GLP, the test substance was examined for its in vitro eye irritating potential using the Isolated Chicken Eye (ICE) Test. In the ICE test, 3 eyes were exposed to 30 µL test substance for 10 seconds. In addition, one negative control eye (30 µL saline) and three positive control eyes (30 µL Benzalkonium Chloride (BAC)) were tested. After the exposure the eyes were rinsed with 20 mL saline and were examined at approximately 0, 30, 75, 120, 180, and 240 minutes after treatment. The tested substance caused no or very slight corneal swelling (mean of 1%), very slight or slight opacity (mean of 0.8) and no or very slight fluorescein retention (mean score 0.3).The negative control eye did not show any corneal effect and demonstrated that the general conditions during the tests were adequate. The positive control BAC 5% caused severe corneal effects and demonstrated the ICE test valid to detect severe eye irritants. Microscopic examination of the corneas treated with the test substance revealed very slight erosion and very slight vacuolation of the epithelium in two corneas. Microscopic examination of the cornea treated with the negative control (saline) did not reveal any abnormalities. Microscopic examination of the corneas treated with the positive control BAC 5% revealed severe erosion and slight vacuolation of the epithelium, the epithelium partly detached from the basement membrane (two corneas), and endothelial necrosis (two corneas). Based on these results, the test substance is considered to be not eye irritating.