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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:
28 July 2008 to 15 August 2008
Reliability:
1 (reliable without restriction)
Rationale for reliability incl. deficiencies:
guideline study

Data source

Reference
Reference Type:
study report
Title:
Unnamed
Year:
2008
Report Date:
2009

Materials and methods

Test guidelineopen allclose all
Qualifier:
according to
Guideline:
OECD Guideline 405 (Acute Eye Irritation / Corrosion)
Deviations:
no
Qualifier:
according to
Guideline:
EU Method B.5 (Acute Toxicity: Eye Irritation / Corrosion)
Deviations:
no
Principles of method if other than guideline:
Study conducted according to standard guideline
GLP compliance:
yes

Test material

Reference
Name:
Unnamed
Type:
Constituent
Test material form:
solid: particulate/powder
Details on test material:
- Name of test material : Tin metal powder (2 – 11 µm)
- Physical state: Solid, grey powder
- Analytical purity: 99.99 %
- Impurities (identity and concentrations): Pb 0.0035 %, Sb 0.0010 %, Cu 0.0003 %, Au 0.0001 %, Al < 0.0001 %, Cd < 0.0001 %, Zn < 0.0002 %, Ag 0.0005 %, Bi 0.0018 %, As 0.0014 %, Fe < 0.0001 %, In 0.0002 %, Ni 0.0002 %, P 0.0016 % and S 0.0028 %
- Purity test date: 05/07/2008
- Lot/batch No.: 061184
- Expiration date of the lot/batch: August 2008
- Storage condition of test material: When not in use the test article was stored in a sealed container, at room temperature in the dark.
Specific details on test material used for the study:
Particle size data is included in the attached image.

Test animals / tissue source

Species:
rabbit
Strain:
New Zealand White
Details on test animals or tissues and environmental conditions:
TEST ANIMALS
- Source: Harlan UK Ltd, Bicester
- Age at study initiation: Approximately 12 to 15 weeks old
- Weight at study initiation: 2.63 to 2.87 kg
- Housing: On arrival, rabbits were accommodated in cages that conform with the 'Code of Practice for the Housing and Care of Animals Used in Scientific Procedures' (Home Office, London, 1989).
- Diet: Global Diet TRB 2930C (Harlan Teklad, Bicester, UK) available ad libitum. Each batch of diet had been analysed for specific constituents and contaminants by the manufacturer. (Global Diet 2030 was specified by the protocol, however the use of Global Diet TRB 2930C was not considered to affect the outcome or integrity of the study).
- Water: Mains water provided ad libitum provided via cage mounted water bottles. The water had been periodically analysed for specific contaminants.
- Acclimation period: 7 to 21 days

ENVIRONMENTAL CONDITIONS
- Temperature: 15 to 21 °C
- Humidity: 40 to 70 % (On three occasions the relative humidity exceeded the specified range with the highest value recorded being 74 %, this is not considered to have affected the integrity or outcome of the study).
- Air changes: 15 changes per hour
- Photoperiod: The rooms were illuminated by fluorescent strip lights for twelve hours daily.

IN-LIFE DATES: From 28 July 2008 to 15 August 2008

In order to enrich both the environment and the welfare of the animals they were, where practicable, provided with wooden Aspen chew blocks and hay.

The condition of the animals was assessed daily throughout the acclimatisation period of 7 to 21 days. A clinical inspection was performed prior to study commencement to ensure the animals were suitable for the test procedures. Overtly healthy animals were arbitrarily allocated to the study on the day before dosing. Both eyes of each rabbit were examined for indications of corneal, iridial or conjunctival damage or irritation. After initial visual examination, one drop of 1 % aqueous fluorescein solution was instilled into both lower conjunctival sacs, allowed to disperse for thirty seconds and removed from the eyes by irrigation with approximately 10 mL water for irrigation jetted gently from a syringe. The corneal surface was illuminated with an ultraviolet source and inspected for areas of absorption of the fluorescing dye that would indicate epithelial damage. Only rabbits with eyes free from damage or irritation were accepted onto study.

Test system

Vehicle:
unchanged (no vehicle)
Controls:
yes, concurrent no treatment
Amount / concentration applied:
TEST MATERIAL
- Amount(s) applied (volume or weight with unit): 100 mg

One dose consisting of 100 mg of test article was instilled into the left conjunctival sac of a single New Zealand White rabbit (the sentinel). The lower eyelid was gently prised away from the eyeball to create a receptacle for the dose. After instillation, the eyelids were held closed for a few seconds to prevent loss of the dose. The right eye remained untreated and served as a control to the treated eye.
Duration of treatment / exposure:
Exposure was indefinite since no immediate rinsing occurred.
Observation period (in vivo):
Animals were assessed for the initial sting/pain response immediately after instillation of the test material. Ocualr assessments were performed at 1, 4 and approximately 24, 48 and 72 hours after instillation
Number of animals or in vitro replicates:
One animal initially, followed by a further two animals.
Details on study design:
REMOVAL OF TEST SUBSTANCE
- Washing (if done): Exposure was indefinite since no immediate rinsing occurred. The treated eyes were subject to fluorescein application and subsequent flushing with water at 24 hours post-instillation and this can be taken to have flushed away any residual test material.

SCORING SYSTEM: At examinations carried out 24 hours after treatemtn (and at the discretion of the observer, at any subsequent examination) the cornea was subject to application of 1 % aqueous fluorescein solution followed by irrigation with water and illumination by an ultraviolet sourve. Damage to the corneal epitheliam was revealed by absorption of the fluorescing dye into the epithelium or stroma. The scoring systems for initial pain response and ocular changes are reported below under section "Any other information on material and methods incl. tables)

TOOL USED TO ASSESS SCORE: pencil-beam torch

The pH of a 50 % dilution of tin metal powder in water was checked prior to exposure of the first eye. The test material was suspended in water at a 50 % w/v dispersion. The pH of the test material was determined to be 5 which is within the acceptable range.

Results and discussion

In vivo

Results
Irritation parameter:
conjunctivae score
Basis:
mean
Time point:
other: 24, 48 and 72 hours
Score:
1
Max. score:
2
Reversibility:
fully reversible within: 72 hours
Remarks on result:
other: Slight conjunctival redness apparent in one treated eye at 24 and 48 hours had resolved by the day 4 assessment
Irritant / corrosive response data:
Instillation of the test article caused no initial sting response.
Minimal conjunctival irritation was noted in two treated eyes 30 minutes and one hour after instillation.
No iridial effects were seen.
No corneal opacity was noted in two treated eyes. There was no corneal absorption of fluorescein solution when applied to these eyes at the 24-hour observation.
Easily discernible areas of corneal opacity were noted in one treated eye on Day 2, with scattered or diffuse areas of opacity noted on Day 3. The application of fluorescein solution at these time points gave fluorescence over an area of < 25 % of the corneal surface.
The eyes of all rabbits were overtly normal by the 72-hour examination.
Other effects:
No observations indicative of systemic toxicity or ill health were noted for any rabbits during the course of the study.

Any other information on results incl. tables

Table 1: Individual and mean scores for cornea, iris and conjunctivae for classification according to Commission Directive 2001/59/EC

Rabbit Number and Sex

Observation Time

Corneal Opacity

Iridial Inflammation

Conjunctival Redness

Conjunctival Chemosis

32 M

24 Hours

0

0

0

0

48 Hours

0

0

0

0

72 Hours

0

0

0

0

Total

0

0

0

0

Mean Score

0.0

0.0

0.0

0.0

33 M

24 Hours

0

0

0

0

48 Hours

0

0

0

0

72 Hours

0

0

0

0

Total

0

0

0

0

Mean Score

0.0

0.0

0.0

0.0

34 M

24 Hours

2

0

0

0

48 Hours

1

0

0

0

72 Hours

0

0

0

0

Total

3

0

0

0

Mean Score

1.0

0.0

0.0

0.0

 

Table 2: Individual ocular responses

Rabbit number and sex

Initial sting response

Observation

Score at time after instillation

½ hr

1 hr

4 hrs

24 hrs

48 hrs

72 hrs

32M

 

 

0

Cornea

Opacity

0#

0#

0#

0*

0

0

Area

0

0

0

0

0

0

Iris

 

0

0

0

0

0

0

 

Conjunctivae

Redness

0

0

0

0

0

0

Chemosis

0

0

0

0

0

0

Discharge

0

0

0

0

0

0

33M

 

 

 

Cornea

Opacity

0#

0#

0

0*

0

0

Area

0

0

0

0

0

0

Iris

 

0

0

0

0

0

0

 

Conjunctivae

Redness

1

1

0

0

0

0

Chemosis

1

1

0

0

0

0

Discharge

0

0

0

0

0

0

34M

 

 

0

Cornea

Opacity

0#

0#

0

2*

1*

0

Area

0

0

0

1

1

0

Iris

 

0

0

0

0

0

0

 

Conjunctivae

Redness

1

1

0

0

0

0

Chemosis

0

0

0

0

0

0

Discharge

0

0

0

0

0

0

* Fluorescein applied to cornea

# Small amount of test article visible on both eyelids

Applicant's summary and conclusion

Interpretation of results:
other: Not classified in accordance with EU criteria
Conclusions:
Tin metal powder instilled as 100 mg into three rabbit eyes did not elicit any significant irritant reactions. Ocular changes (slight conjunctival and corneal responses) had resolved by day 4. No classification as an ocular irritant is appropriate.
Executive summary:

Tin metal powder (2 -11 µm) was instilled, as 100 mg, into the lower conjunctival sac of three NZW rabbits. Ocular changes were assessed at 1, 4, 24, 48 and 72 hours post-exposure and fluorescein was applied after 24 hours.

Transient conjunctival redness and swelling occurred in two rabbits on day 1 and corneal opacity was briefly apparent for one animal on day 2/3. No iridial changes were noted. All reactions had overtly resolved by day 4 and the mean scores for each irritation parameter were below the threshold for classification.