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Toxicological information

Eye irritation

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Administrative data

Endpoint:
eye irritation: in vitro / ex vivo
Type of information:
experimental study
Adequacy of study:
weight of evidence
Study period:
2016-02-03 to 2016-03-09
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 guidelineopen allclose all
Qualifier:
according to
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)
Version / remarks:
2013
Deviations:
no
Qualifier:
according to
Guideline:
EU method B.48 (Isolated chicken eye test method for identifying occular corrosives and severe irritants)
Version / remarks:
2010
Deviations:
no
GLP compliance:
yes (incl. certificate)

Test material

Reference
Name:
Unnamed
Type:
Constituent
Test material form:
liquid

Test animals / tissue source

Species:
chicken
Strain:
other: ROSS 308
Details on test animals or tissues and environmental conditions:
SOURCE OF COLLECTED EYES
- Source: TARAVIS KFT. 9600 Sárvár, Rábasömjéni út 129. Hungary
- Storage, temperature and transport conditions of ocular tissue: Head collection was performed by a slaughter house technician. Heads were removed immediately after sedation of the chickens (sedation was happened by electric current). The heads were transported to Toxi-Coop ZRT at the earliest convenience for use approximately within 2 hours from collection. The ambient temperature was optimal (19.5ºC to 20.5 ºC) during the transport. All eyes used in the assay were from the same groups of eyes collected on one specific day.
- indication of any existing defects or lesions in ocular tissue samples: After collection, the heads were inspected for appropriate quality and wrapped with paper moistened with saline, then placed in a plastic box that can be closed (4-5 heads/box).

Test system

Vehicle:
unchanged (no vehicle)
Controls:
yes, concurrent positive control
yes, concurrent negative control
Amount / concentration applied:
TEST MATERIAL
- Amount(s) applied: The undiluted test item was applied at a volume of 30 μL from a micropipette, in such a way that the entire surface of the cornea was covered with test substance.
Duration of treatment / exposure:
The time of application was monitored. After an exposure period of 10 seconds the cornea surface was rinsed thoroughly with 20 mL saline solution at ambient temperature, while taking care not to damage the cornea but attempting to remove the entire residual test item, if possible. The eye in the holder was then returned to its chamber. The time while the eye was out of the chamber was limited to a minimum.
Duration of post- treatment incubation (in vitro):
The control and test item treated eyes were evaluated pre-treatment and at approximately 30, 75, 120, 180 and 240 minutes after the post-treatment rinse. Minor variations within ± 5 minutes were considered acceptable.
Number of animals or in vitro replicates:
3
Details on study design:
SELECTION AND PREPARATION OF ISOLATED EYES
Eyes selection:
After removing the head from the plastic box, it was put on soft paper. The eyelids were carefully cut away with scissors, avoiding damaging the cornea. One small drop of fluorescein solution 2 % (w/v) was applied onto the cornea surface for a few seconds and subsequently rinsed off with 20 mL saline solution. Then the fluorescein-treated cornea was examined with a slit lamp microscope, with the eye in the head, to ensure that the cornea was not damaged (i.e., fluorescein retention ≤ 0.5). If the cornea was in good condition, the eyeball was carefully removed from the orbit.
Preparation of eyes:
The eye ball was carefully removed from the orbit by holding the nictitating membrane with a surgical forceps, while cutting the eye muscles with bent scissors. Care was taken to remove the eyeball from the orbit without cutting off the optical nerve too short. The procedure avoided pressure on the eye while removing the eyeball from the orbit, in order to prevent distortion of the cornea and subsequent corneal opacity. Once removed from the orbit, the eye was placed onto damp paper. The nictitating membrane and other connective tissue were cut away. The prepared eyes were kept on wet papers in a closed box to maintain an appropriate humidity. The treatment group and the concurrent positive control consisted of three eyes. The negative control group consisted of one eye.
Eyes examination and acclimatisation time:
The enucleated eye was placed in a steel clamp with the cornea positioned vertically with the eye in the correct relative position (same position as in the chicken head). Again, too much pressure on the eye by the clamp was avoided. Because of the relatively firm sclera of the chicken eyeball, only slight pressure was needed to fix the eye properly. The clamp with the eyeball was 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 saline solution dripping from a stainless steel tube, at a rate of approximately 3 or 4 drops/minute. The door of the chamber was closed except for manipulations and examinations, to maintain temperature and humidity.
The appropriate number of eyes was selected and, after being placed in the superfusion apparatus, the eyes were examined again with the slit lamp microscope to ensure that they were in good condition. The focus was adjusted to see clearly the saline solution which was flowing on the cornea surface. Eyes with a high baseline fluorescein staining (i.e., > 0.5) or a high corneal opacity score (i.e., > 0.5) were rejected. The cornea thickness was measured using the depth measuring device on the slit lamp microscope (Haag-Streit BQ 900) with the slit-width set at 9½, equaling 0.095 mm. Any eye with cornea thickness deviating more than 10 % from the mean value for the eyes, or eyes that showed any other signs of damage, were rejected and replaced. If the selected eyes were appropriate for the test, acclimatisation started and was conducted for approximately 45 to 60 minutes. The temperature of the circulating water was verified to ensure that the temperature in all chambers was in the range of 32 ± 1.5 °C during the acclimatisation and treatment periods.

EQUILIBRATION AND BASELINE RECORDINGS
At the end of the acclimatization period, a zero reference measurement was recorded for cornea thickness, opacity, and fluorescein retention to serve as a baseline (t=0) for each individual eye. The cornea thickness of the eyes should not change by more than ±5-7 % within approximately 45 to 60 minutes before the start of application. No changes in thickness were observed in the eyes. Following the equilibration period, the fluorescein retention was measured. Baseline values were required to evaluate any potential test item related effects after treatment. If any eye was considered to be unsuitable following baseline assessment, it was discarded.

NUMBER OF REPLICATES: 3

NEGATIVE CONTROL USED: Saline

POSITIVE CONTROL USED: Acetic acid 10% (v/v)

APPLICATION DOSE AND EXPOSURE TIME: 30 µL for 10 sec

OBSERVATION PERIOD: The control and test item treated eyes were evaluated pre-treatment and at approximately 30, 75, 120, 180 and 240 minutes after the post-treatment rinse. Minor variations within ± 5 minutes were considered acceptable.
The cornea thickness and cornea opacity were measured at all time points. Fluorescein retention was measured on two occasions, at base line (t=0) and 30 minutes after the post-treatment rinse.

REMOVAL OF TEST SUBSTANCE
- Volume and washing procedure after exposure period: The time of application was monitored. After an exposure period of 10 seconds the cornea surface was rinsed thoroughly with 20 mL saline solution at ambient temperature, while taking care not to damage the cornea but attempting to remove the entire residual test item, if possible. The eye in the holder was then returned to its chamber. The time while the eye was out of the chamber was limited to a minimum.

METHODS FOR MEASURED ENDPOINTS:
The endpoints evaluated were corneal opacity, swelling, fluorescein retention, and morphological effects (e.g., pitting or loosening of the epithelium).
Results from corneal opacity, swelling, and fluorescein retention were evaluated separately to generate an Isolated Chicken Eye (ICE) class for each endpoint. The ICE classes for each endpoint were then combined to generate an Irritancy Classification for each test substance.

SCORING SYSTEM:
The endpoints evaluated were corneal opacity, swelling, fluorescein retention, and morphological effects (e.g., pitting or loosening of the epithelium).
Results from corneal opacity, swelling, and fluorescein retention were evaluated separately to generate an Isolated Chicken Eye (ICE) class for each endpoint. The ICE classes for each endpoint were then combined to generate an Irritancy Classification for each test substance.

DECISION CRITERIA: The conclusion on eye irritancy was based on the OECD guideline on quantitative assessments.

Results and discussion

In vitro

Resultsopen allclose all
Irritation parameter:
percent corneal swelling
Run / experiment:
at up to 75 min
Value:
7
Vehicle controls validity:
not applicable
Negative controls validity:
valid
Positive controls validity:
valid
Irritation parameter:
percent corneal swelling
Run / experiment:
at up to 240 min
Value:
9
Vehicle controls validity:
not applicable
Negative controls validity:
valid
Positive controls validity:
valid
Irritation parameter:
fluorescein leakage
Run / experiment:
mean
Value:
1
Vehicle controls validity:
not applicable
Negative controls validity:
valid
Positive controls validity:
valid
Irritation parameter:
cornea opacity score
Run / experiment:
mean maximum
Value:
0.8
Vehicle controls validity:
not applicable
Negative controls validity:
valid
Positive controls validity:
valid
Other effects / acceptance of results:
OTHER EFFECTS:
- Visible damage on test system: None.

ACCEPTANCE OF RESULTS:
- Acceptance criteria met for negative control: yes. Based on the overall ICE Class the negative control NaCl (9 g/L saline) had no significant effects on the chicken eye in this study.
- Acceptance criteria met for positive control: yes. Based on the overall ICE Class the positive control Acetic acid 10 % (v/v) solution was classed as corrosive/severely irritating, UN GHS Classification: Category 1.
- Range of historical values if different from the ones specified in the test guideline: Positive and negative control values were within the corresponding historical control data ranges.

Applicant's summary and conclusion

Conclusions:
In this in vitro eye corrosives and severe irritants study, using the Isolated Chicken Eye model with the test item, no ocular corrosion or severe irritation potential was observed. The overall ICE score was 3xII.
Executive summary:

The purpose of this Isolated Chicken Eye Test (ICET) was to evaluate the potential ocular corrosivity or severe irritancy of the test item by its ability to induce toxicity in enucleated chicken eyes. The test compound was applied in a single dose (30 μL /eye) onto the cornea of isolated chicken eyes in order to potentially classify the test compound as either 1: causing "serious eye damage" [category 1 of the Globally Harmonised System for the Classification and Labelling of chemicals (GHS)], or 2: not requiring classification for eye irritation or serious eye damage according to the GHS. The ICET does not fully replace the in vivo rabbit eye test (OECD 405); however, the ICET is used as part of a tiered testing strategy for regulatory purposes.

Results

The test item, Acetic acid 10 % (v/v) solution (positive control) and NaCl (9 g/L saline) (negative control) were applied in such a way that the entire surface of the cornea was uniformly covered with the test substance or positive or negative control. Three test item treated eyes and three positive control eyes and one negative control eye were used in this study. After an exposure period of 10 seconds from the end of the application the cornea surface was rinsed thoroughly with ~20 mL saline solution at ambient temperature and this procedure was repeated for each eye. In this ICET, the test item did not cause ocular corrosion or severe irritation in the enucleated chicken eyes. Positive and negative controls showed the expected results. The experiments were considered to be valid.