3A-Flux

Eye irritation

Administrative data

Endpoint:

eye irritation: in vivo

Type of information:

experimental study

Adequacy of study:

key study

Study period:

2013-01-24 - 2013-03-27

Reliability:

1 (reliable without restriction)

Rationale for reliability incl. deficiencies:

other: GLP guideline study.

Justification for type of information:

Read-across is justified on the following basis: In aqueous solutions at physiological and acidic pH, low concentrations of simple inorganic borates such as boric acid, disodium tetraborate decahydrate, disodium tetraborate pentahydrate, boric oxide and disodium octaborate tetrahydrate will predominantly exist as undissociated boric acid. At about pH 10 the metaborate anion (B(OH)4-) becomes the main species in solution (WHO, 1998). This leads to the conclusion that the main species in the plasma of mammals and in the environment is un-dissociated boric acid. Since other borates dissociate to form boric acid in aqueous solutions, they too can be considered to exist as un-dissociated boric acid under the same conditions. For comparative purposes, exposures to borates are often expressed in terms of boron (B) equivalents based on the fraction of boron in the source substance on a molecular weight basis. Some studies express dose in terms of B, whereas other studies express the dose in units of boric acid. Since the systemic effects and some of the local effects can be traced back to boric acid, results from one substance can be transferred to also evaluate the another substance on the basis of boron equivalents. Therefore data obtained from studies with these borates can be read across in the human health assessment for each individual substance. Conversion factors are given in the table below. Conversion factor for equivalent dose of B Boric acid H3BO3 0.175 Boric Oxide B2O3 0.311 Disodium tetraborate anhydrous Na2B4O7 0.215 Disodium tetraborate pentahydrate Na2B4O7•5H2O 0.148 Disodium tetraborate decahydrate Na2B4O7•10H2O 0.113 Disodium octaborate tetrahydrate Na2B8O13•4H2O 0.210 Sodium metaborate (anhydrous) NaBO2 0.1643 Sodium metaborate (dihydrate) NaBO2•2H2O 0.1062 Sodium metaborate (tetrahydrate) NaBO2•4H2O 0.0784 Sodium pentaborate (anhydrous) NaB5O8 0.2636 Sodium pentaborate (pentahydrate) NaB5O8∙5H2O 0.1832 References: WHO. Guidelines for drinking-water quality, Addendum to Volume 1, 1998.

Data source

Reference

Reference Type:

study report

Title:

Unnamed

Year:

2013

Report date:

2013

Materials and methods

Test guideline

Qualifier:

according to guideline

Guideline:

OECD Guideline 405 (Acute Eye Irritation / Corrosion)

Deviations:

no

GLP compliance:

yes

Test material

Test material information

Constituent 1

Reference substance name:

Reference substance 001

Cas Number:

12045-78-2

Molecular formula:

n.a.

Details on test material:

- Name of test material: dipotassium tetraborate tetrahydrate
- Physical state: White powder
- Analytical purity: > 99 %
- Lot/batch No.: MH01

Test animals / tissue source

Species:

rabbit

Strain:

New Zealand White

Details on test animals or tissues and environmental conditions:

TEST ANIMALS
- Source: Kuiper Rabbit Ranch (Gary, IN).
- Age at study initiation: Approximately four months.
- Weight at study initiation: 3.24 – 3.4 kg
- Housing: The rabbits were housed individually in stainless steel cages suspended over excrement pans. Cage liners were placed in the pan below the stainless steel mesh floor of each animal cage to absorb liquids.
- Diet (e.g. ad libitum): Each rabbit was provided with approximately 150 g of Harlan Teklad (Harlan Laboratories, Madison, WI) Certified High Fiber Rabbit Diet #2031 daily.
- Water (e.g. ad libitum): Was Supplied ad libitum by means of an automatic watering system.


ENVIRONMENTAL CONDITIONS
- Temperature (°C): 21°C to 22°C
- Humidity (%): 41% to 52%
- Photoperiod (hrs dark / hrs light): 12 hours of light followed by 12 hours of darkness.

Test system

Vehicle:

unchanged (no vehicle)

Controls:

other: Left eye served as a control and was not treated.

Amount / concentration applied:

0.1 g

Duration of treatment / exposure:

24 hours

Observation period (in vivo):

72 hours

Number of animals or in vitro replicates:

Five per sex.

Details on study design:

REMOVAL OF TEST SUBSTANCE
- Washing (if done): Eyes were washed with room temperature water for 30 seconds using a volume and velocity that would not cause injury.
- Time after start of exposure: 24 hours after administration.

SCORING SYSTEM: For each animal, mean scores for corneal opacity, iris lesions, conjunctival redness and conjunctival chemosis were calculated by adding the 24-, 48- and 72-hour post-dose scores for the respective parameter and dividing by three. The irritation potential of the test substance was assessed according to the following criteria, based upon the European Parliament and the Council of the European Union guidelines (Regulation (EC) No. 1272/2008, Dec. 2008):
- The test substance will be considered a nonirritant if, in at least two animals, the corneal opacity mean score is less than 1.0, the iris lesion mean score is less
than 1.0, the conjunctival redness mean score is less than 2.0, and the chemosis mean score is less than 2.0.
- The test substance will be considered a Category 2 (reversible eye effects) irritant if at least two of the three rabbits have a corneal opacity mean score greater than or equal to 1.0 but less than 3.0 and/or an iris lesion mean score greater than or equal to 1.0 but less than 1.5 and/or a conjunctival redness mean score greater than or equal to 2.0 and/or a chemosis mean score greater than or equal to 2.0.
- The test substance will be considered a Category 1 (irreversible eye effects) irritant if the corneal opacity mean score is greater than or equal to 3.0 and/or the iris lesion mean score is greater than 1.5 in at least two of the three rabbits tested.

TOOL USED TO ASSESS SCORE: The eye examinations were performed using a slit penlight and the treated eyes were scored for ocular reaction of the cornea, iris, conjunctivae, lids and nictitating membranes. Fluorescein stain was used to aid in the examination for corneal lesions at the 24-hour scoring interval.

Results and discussion

In vivo

Results

Results 1

Irritation parameter:

chemosis score

Basis:

animal #1

Time point:

24/48/72 h

Score:

1

Max. score:

4

Reversibility:

fully reversible within: 7 days

Results 2

Irritation parameter:

chemosis score

Basis:

animal #2

Time point:

24/48/72 h

Score:

1

Max. score:

4

Reversibility:

fully reversible within: 7 days

Results 3

Irritation parameter:

chemosis score

Basis:

animal #3

Time point:

24/48/72 h

Score:

>= 0 - <= 1

Max. score:

4

Reversibility:

fully reversible within: 7 days

Remarks on result:

other: Score for 24 h: 0, for others: 1

Results 4

Irritation parameter:

conjunctivae score

Remarks:

Redness

Basis:

animal #1

Time point:

24/48/72 h

Score:

1

Max. score:

3

Reversibility:

fully reversible within: 14 days

Results 5

Irritation parameter:

conjunctivae score

Remarks:

Redness

Basis:

animal #2

Time point:

24/48/72 h

Score:

1

Max. score:

3

Reversibility:

fully reversible within: 7 days

Results 6

Irritation parameter:

conjunctivae score

Remarks:

Redness

Basis:

animal #3

Time point:

24/48/72 h

Score:

1

Max. score:

3

Reversibility:

fully reversible within: 7 days

Results 7

Irritation parameter:

iris score

Basis:

animal #1

Time point:

24/48/72 h

Score:

0

Max. score:

2

Reversibility:

fully reversible within: 14 days

Remarks on result:

no indication of irritation

Results 8

Irritation parameter:

iris score

Basis:

animal #2

Time point:

24/48/72 h

Score:

0

Max. score:

2

Reversibility:

fully reversible within: 7 days

Remarks on result:

no indication of irritation

Results 9

Irritation parameter:

iris score

Basis:

animal #3

Time point:

24/48/72 h

Score:

0

Max. score:

2

Reversibility:

fully reversible within: 7 days

Remarks on result:

no indication of irritation

Results 10

Irritation parameter:

cornea opacity score

Basis:

animal #1

Time point:

24/48/72 h

Score:

>= 0 - <= 1

Max. score:

4

Reversibility:

fully reversible within: 7 days

Remarks on result:

other: Score for 24 h and 48 h: 1, for others: 0

Results 11

Irritation parameter:

cornea opacity score

Basis:

animal #2

Time point:

24/48/72 h

Score:

>= 0 - <= 1

Max. score:

4

Reversibility:

fully reversible within: 7 days

Remarks on result:

other: Score for 24 h: 1, for others: 0

Results 12

Irritation parameter:

cornea opacity score

Basis:

animal #3

Time point:

24/48/72 h

Score:

0

Max. score:

4

Reversibility:

other: not applicable

Remarks on result:

no indication of irritation

Any other information on results incl. tables

Mortality

No rabbits died during the study prior to scheduled euthanisation, nor were any adverse clinical observations noted at any time during the study.

Ocular Observations

No positive irritation scores were observed in any animal throughout the study for iris lesions. Conjunctival redness scores were 1.0 for all animals, and conjunctival chemosis scores ranged from 0.7 to 1.0. No signs of any ocular irritation were present at 14 days after dosing (initial testing) or 7 days after dosing (confirmatory testing).

Individual and Mean Eye Irritation Scores

1. Cornea (A = Density of Opacity; B = Area of Opacity)

Animal Number (Sex)	1 Hour		24 Hours		48 Hours		72 Hours		7 Days		14 days^c		Mean^d
	A	B	A	B	A	B	A	B	A	B	A	B
804 (M)	0	-^a	1	-^b	1	-^b	0	-	0	-	0	-	0.7
805 (M)	0	-	1	-^b	0	-	0	-	0	-	NA	NA	0.7
806 (F)	0	-	0	-	0	-	0	-	0	-	NA	NA	0.0

^a - = not applicable (no opacity)

^b scattered/diffuse

^c initial testing (animal 804) only

^d Mean = sum of individual animal "A" scores at the 24 -, 48- and 72 -hour scoring intervals divided by 3.

2. Iris

Animal Number (Sex)	1 Hour	24 Hours	48 Hours	72 Hours	7 Days	14 Days^a	Mean^b
804 (M)	0	0	0	0	0	0	0.0
805 (M)	0	0	0	0	0	NA	0.0
806 (F)	0	0	0	0	0	NA	0.0

^a initial testing (animal 804) only

^b Mean = sum of individual animal "A" scores at the 24 -, 48- and 72 -hour scoring intervals divided by 3.

3. Conjunctiva (A = Redness; B = Chemosis)

Animal Number (Sex)	1 Hour		24 Hours		48 Hours		72 Hours		7 Days		14 Days^a		Mean^b
	A	B	A	B	A	B	A	B	A	B	A	B	A	B
804 (M)	1	1	1	1	1	1	1	1	1	0	0	0	1.0	1.0
805 (M)	1	1	1	1	1	1	1	1	0	0	NA	NA	1.0	1.0
806 (F)	1	1	1	0	1	1	1	1	0	0	NA	NA	1.0	0.7

^a initial testing (animal 804) only

^b Mean ("A" and "B" scores, respectively) = sum of individual animal scores at the 24 -, 48- and 72 -hour scoring intervals divided by 3.

Applicant's summary and conclusion

Interpretation of results:

GHS criteria not met

Conclusions:

Potassium tetraborate is classified as a nonirritant to the eyes of New Zealand White rabbits, based on corneal opacity mean scores of less than 1.0, iris lesion mean scores ofless than 1.0, conjunctival redness mean scores of less than 2.0, and chemosis mean scores of less than 2.0 in at least two of the three rabbits tested [European Parliament and the Council of the European Union guidelines (Regulation (EC) No. 1272/2008, Dec. 2008)]. Recovery from all signs of irritation had occurred by 14 days after dosing (initial testing) or 7 days after dosing (confirmatory testing) with potassium tetraborate.