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Toxicological information

Eye irritation

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Administrative data

Endpoint:
eye irritation: in vivo
Type of information:
experimental study
Adequacy of study:
key study
Study period:
24 October 2019 to 29 October 2019
Reliability:
1 (reliable without restriction)
Rationale for reliability incl. deficiencies:
guideline study

Data source

Reference
Reference Type:
study report
Title:
Unnamed
Year:
2020
Report date:
2020

Materials and methods

Test guideline
Qualifier:
according to guideline
Guideline:
OECD Guideline 405 (Acute Eye Irritation / Corrosion)
Deviations:
no
GLP compliance:
yes (incl. QA statement)

Test material

Constituent 1
Chemical structure
Reference substance name:
Zirconium oxide, erbium and yttrium doped
EC Number:
947-747-7
Molecular formula:
(ZrO2)x(Y2O3)y(Er2O3)z 0.946 < x < 0.991 0.003 < y < 0.029 0.007 < z < 0.024
IUPAC Name:
Zirconium oxide, erbium and yttrium doped
Test material form:
solid: particulate/powder
Details on test material:
- Expiry date: 01 August 2020.
- Storage conditions: Controlled room temperature (15 – 25 °C, ≤ 70 % RH), protected from humidity (tightly closed container).

Test animals / tissue source

Species:
rabbit
Strain:
New Zealand White
Details on test animals or tissues and environmental conditions:
TEST ANIMALS
- Age at study initiation: 14 week old (young adult) males.
- Weight at study initiation: 3730 g - 3825 g.
- Housing: Rabbits were individually housed in AAALAC approved metal wire rabbit cages.
- Diet: Ad libitum.
- Water: Ad libitum.
- Acclimation period: At least 36 days. Only animals in acceptable health condition were used for the test. The veterinarian certified health status. Both eyes of each animal provisionally selected for testing were examined prior to starting the study. Animals showing eye irritation, ocular defects or pre-existing corneal injury were not used.

ENVIRONMENTAL CONDITIONS
- Temperature (°C): 20.7 – 23.0 °C.
- Humidity (%): 42 – 64 %.
- Air changes (per hr): 15 - 20 air exchanges/hour.
- Photoperiod (hrs dark / hrs light): Light 12 hours daily, from 6.00 a.m. to 6.00 p.m.

Test system

Vehicle:
unchanged (no vehicle)
Controls:
other: The untreated right eye served as control.
Amount / concentration applied:
TEST MATERIAL
- Amount(s) applied: A single amount of 0.1 g of the test material was administered to the left eye of each animal.
Duration of treatment / exposure:
1 hour
Observation period (in vivo):
72 hours
Number of animals or in vitro replicates:
Three animals
Details on study design:
IDENTIFICATION OF pH
- The pH of the test material was measured prior to the start of treatment and it was found to be 6.25, so the test material is permitted for use in animal studies.

PRE-STUDY EXAMINATION
- Three male animals in acceptable health condition were selected for the test. Care was taken to select only those animals that had a normal eye condition.

ADMINISTRATION
- Initially only one rabbit was treated with test material. All scores were zero at 24 hours after the application, therefore two additional rabbits were treated after the 48-hour observation of the first rabbit. No clinical signs were observed in any animals during the observation period; the experiment was terminated after 72 hours observation of the second and third rabbits.
- The test material was placed in the conjunctival sac of the left eye of each animal after gently pulling the lower lid away from the eyeball. The lids were then gently held together for at least one second in order to prevent loss of the material. The untreated contralateral eye served as the control.
- The eyes were examined at approximately 1, 24, 48, 72 hours after treatment. The duration of the observation period was sufficient to identify reversibility or irreversibility of changes. Any clinical signs of toxicity or signs of ill-health during the study were recorded. At the end of the observation period, the animal was sacrificed by intravenous sodium pentobarbital. Death was verified by checking pupil and corneal reflex and the absence of respiration and pulse.
- All rabbits were examined for distress at least twice daily, with observations at least 6 hours apart. Clinical observations or signs of ill-health were recorded.
- Analgesic and Anaesthetic Treatment: Sixty minutes (60 ± 10 min) prior to test material application, a systemic opiate analgesic was administered by subcutaneous injection (SC) under direct Veterinary supervision. Repeat injections were given on the first and second days as appropriate to maintain an adequate level of analgesia. Five minutes (5 ± 1.5 min) prior to test material application, a topical ocular anaesthetic was applied to each eye (including the control eye to ensure direct comparison of any ocular observations).
Eight hours (8 to 9 hr) after test material application, a systemic opiate analgesic and a nonsteroidal anti-inflammatory drug (NSAID) were administered by subcutaneous injection under direct Veterinary supervision. The systemic opiate analgesic was again injected ~12 hours after the post-treatment analgesic.
Systemic Opiate Analgesic: Bupredine Multidose (0.3 mg/mL buprenorphine)
Topical Ocular Anaesthetic: Benoxi (4 mg/mL oxybuprocaine - hydrochloride)
Nonsteroidal Anti - inflammatory Drug: Melovem®(5 mg/mL meloxicam)

REMOVAL OF TEST SUBSTANCE
- Washing: Solid test material was observed in the treated eye of the test animals at the 1-hour observation point. As such the treated eye was rinsed with physiological saline solution.
- Time after start of exposure: At the 1-hour observation point.

SCORING SYSTEM
- Individual reactions of the animals were recorded at each observation time. The nature, severity and duration of all lesions observed were described.
- The eye irritation scores were evaluated according to the scoring system by Draize (1977) and OECD 405 (09 October 2017).
Scoring and Assessment of Local Reaction
1. Conjunctivae
A. Redness (Palpebral and bulbar)
0 Normal
1 Some blood vessels hyperaemic (injected)
2 Diffuse, crimson colour, individual vessels not easily discernible
3 Diffuse beefy red.

B. Chemosis
0 Normal
1 Some swelling above normal (includes nictating membrane)
2  Obvious swelling with partial eversion of lids
3 Swelling with lids about half closed
4 Swelling with lids more than half closed.

C. Discharge
0 No discharge
1 Any amount different from normal (does not include small amounts observed in inner canthus of normal animals)
2 Discharge with moistening of the lids and hairs just adjacent to lids
3 Discharge with moistening of the lids and hairs, on considerable area around the eye.

2. Iris
0 Normal
1 Markedly deepened rugae, congestion, swelling, moderate circumcorneal hyperaemia: or injection: iris reactive to light (a sluggish reaction is considered to be an effect)
2 Haemorrhage, gross destruction, or no reaction to light.

3. Cornea
E. Opacity - Degree of Density (Area most dense taken for reading)
0 No ulceration or opacity
1 Scattered or diffuse areas of opacity (other than slight dulling of normal lustre): details of iris clearly visible
2 Easily discernible translucent area: details of iris slightly obscured
3 Nacrous area: no details of iris visible: size of pupil barely discernible
4 Opaque cornea: iris not discernible through the opacity.

F. Area of Cornea Involved
1 One quarter (or less), but not zero
2 Greater than one quarter, but less than half
3 Greater than half, but less than three quarters
4 Greater than three quarters, up to whole area.

Any Other Lesions in the Eye (e.g. pannus, staining, anterior chamber changes): Text description, or 0 if absent.

BODY WEIGHT
- Individual body weight was recorded on the day of treatment and at the end of observation period of each animal.

Results and discussion

In vivo

Resultsopen allclose all
Irritation parameter:
conjunctivae score
Basis:
animal #1
Time point:
24/48/72 h
Score:
0
Max. score:
3
Reversibility:
other: No effects observed.
Remarks on result:
no indication of irritation
Irritation parameter:
conjunctivae score
Basis:
animal #2
Time point:
24/48/72 h
Score:
0
Max. score:
3
Reversibility:
other: No effects observed.
Remarks on result:
no indication of irritation
Irritation parameter:
conjunctivae score
Basis:
animal #3
Time point:
24/48/72 h
Score:
0.33
Max. score:
3
Reversibility:
fully reversible within: 48 hours
Remarks on result:
no indication of irritation
Irritation parameter:
chemosis score
Basis:
animal #1
Time point:
24/48/72 h
Score:
0
Max. score:
4
Reversibility:
other: No effects observed.
Remarks on result:
no indication of irritation
Irritation parameter:
chemosis score
Basis:
animal #2
Time point:
24/48/72 h
Score:
0
Max. score:
4
Reversibility:
other: No effects observed.
Remarks on result:
no indication of irritation
Irritation parameter:
chemosis score
Basis:
animal #3
Time point:
24/48/72 h
Score:
0.33
Max. score:
4
Reversibility:
fully reversible within: 48 hours
Remarks on result:
no indication of irritation
Irritation parameter:
cornea opacity score
Basis:
animal #1
Time point:
24/48/72 h
Score:
0
Max. score:
4
Reversibility:
other: No effects observed.
Remarks on result:
no indication of irritation
Irritation parameter:
cornea opacity score
Basis:
animal #2
Time point:
24/48/72 h
Score:
0
Max. score:
4
Reversibility:
other: No effects observed.
Remarks on result:
no indication of irritation
Irritation parameter:
cornea opacity score
Basis:
animal #3
Time point:
24/48/72 h
Score:
0
Max. score:
4
Reversibility:
other: No effects observed.
Remarks on result:
no indication of irritation
Irritation parameter:
iris score
Basis:
animal #1
Time point:
24/48/72 h
Score:
0
Max. score:
2
Reversibility:
other: No effects observed.
Remarks on result:
no indication of irritation
Irritation parameter:
iris score
Basis:
animal #2
Time point:
24/48/72 h
Score:
0
Max. score:
2
Reversibility:
other: No effects observed.
Remarks on result:
no indication of irritation
Irritation parameter:
iris score
Basis:
animal #3
Time point:
24/48/72 h
Score:
0
Max. score:
2
Reversibility:
other: No effects observed.
Remarks on result:
no indication of irritation
Irritant / corrosive response data:
Examination of Ocular Reactions
No Initial Pain Reaction/Pain reaction (IPR/PR) was observed.
 
Animal 1 (No. 2091) Clinical Observation
At 1 hour after the application, conjunctival redness (score 2), chemosis (score 1) and discharge (score 1) were noted in the rabbit. Remaining test material was noted in the eye sac.
At 24, 48 and 72 hours after the application, no clinical signs and no ocular reactions (conjunctivae, cornea and iris) were observed.
 
Animal 2 (No: 2094) Clinical Observation
At 1 hour after the application, conjunctival redness (score 2), chemosis (score 1) and discharge (score 1) were noted in the rabbit. Remaining test material was noted in the eye sac.
At 24, 48 and 72 hours after the application, no clinical signs and no ocular reactions (conjunctivae, cornea and iris) were observed.
 
Animal 3 (No: 2199) Clinical Observation
At 1 hour after the application, conjunctival redness (score 2), chemosis (score 1) and discharge (score 1) were noted in the rabbit. Remaining test material was noted in the eye sac.
At 24 hours after the application, conjunctival redness (score 1) and chemosis (score 1) were noted in the rabbit.
At 48 and 72 hours after the application, no clinical signs and no ocular reactions (conjunctivae, cornea and iris) were observed.

As no clinical signs were observed, the experiment was terminated after 72 hours observation of the second and third rabbits. During the experiment, the control eye of each animal was symptom-free. Solid test material was observed in the treated eye of the test animals at the 1-hour observation point. As such, the treated eye of all animals was rinsed with physiological saline solution at the 1-hour observation point in line with the OECD guidance. The general state and behaviour of animals were normal throughout the study period.
Other effects:
MORTALITY
There was no mortality observed during the study.
 
BODY WEIGHTS
The body weight of the animals was considered to be within the normal range of variability.

CLINICAL OBSERVATIONS
There were no clinical signs observed that could be related to treatment.

Applicant's summary and conclusion

Interpretation of results:
other: Not classified according to EU criteria.
Conclusions:
Under the conditions of the study the test material is not classified as irritant according to EU criteria.
Executive summary:

The in vivo eye irritation potential of the test material was assessed in rabbits according to OECD Test Guideline 405 and in compliance with GLP.

Three rabbits were treated with the test material. Prior to test material application, the animals were treated with analgesic and anaesthetic as per the regulatory guideline. The test material was placed into the conjunctival sac of the left eye of each animal. The untreated right eye served as control. A single amount of 0.1 g of the test material was administered to the left eye of each animal. The eyes were examined at 1, 24, 48 and 72 hours after application.

No Initial Pain Reaction/Pain reaction (IPR/PR) was observed. At 1 hour after the application, conjunctival redness (score 2), chemosis (score 1) and discharge (score 1) were noted in the three rabbits. Remaining test material was noted in the left eye sac of all animals. As such the treated eye was rinsed with physiological saline solution at the 1 - hour observation point.

At 24 hours after application, conjunctival redness (score 1) and chemosis (score 1) were noted in one rabbit. No clinical signs and no ocular reactions (conjunctivae, cornea and iris) were observed in other animals. At 48 and 72 hours after the application, no clinical signs and no ocular reactions (conjunctivae, cornea and iris) were observed in any animals. During the experiment, the control eye of each animal was symptom-free. No mortality occurred during the study. The general state and behaviour of animals were normal throughout the study period. The bodyweights of all rabbits were considered to be within the normal range of variability. As no clinical signs were observed, the experiment was terminated after 72 hours observation of the second and third rabbits.

Test material, applied to rabbit eye mucosa, caused conjunctival effects at 1 hour and 24 hours after the treatment, which were fully reversible within a maximum of 48 hours. There were no effects on cornea and iris observed during the study.

Under the conditions of the study the test material was not classified according to EU criteria.