Dilithium tetraborate

Eye irritation

Administrative data

Endpoint:

eye irritation: in vitro / ex vivo

Type of information:

experimental study

Adequacy of study:

key study

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 437 (Bovine Corneal Opacity and Permeability Test Method for Identifying Ocular Corrosives and Severe Irritants)

Version / remarks:

Adopted July 26th 2013

Deviations:

no

GLP compliance:

yes

Test material

Test material information

Constituent 1

Reference substance name:

Dilithium tetraborate

EC Number:

234-514-3

EC Name:

Dilithium tetraborate

Cas Number:

12007-60-2

Molecular formula:

B4Li2O7

IUPAC Name:

dilithium tetraborate

Test material form:

solid: bulk

Test animals / tissue source

Species:

cattle

Strain:

not specified

Details on test animals or tissues and environmental conditions:

Bovine eyes from young cattle were obtained from the slaughterhouse were used in this study. The eyes were checked for unacceptable defects, such as opacity, scratches, pigmentation and neovascularization by removing them from the physiological saline and holding them in the light. Those exhibiting defects were discarded.

Test system

Vehicle:

unchanged (no vehicle)

Controls:

yes, concurrent positive control

yes, concurrent negative control

Amount / concentration applied:

Since no workable suspension in physiological saline could be obtained, the test item was used as delivered and added pure on top of the corneas.

Duration of treatment / exposure:

The eye damage of dilithium tetraborate was tested through topical application for approximately 240 minutes

Duration of post- treatment incubation (in vitro):

90 minutes

Number of animals or in vitro replicates:

Two identical experiments were undertaken

Details on study design:

The test consists of topical application of dilithium tetraborate on the epithelium of the bovine cornea for 4 hours. The non-surfactant solid test item is applied neat by direct application to the surface of the cornea. After exposure the corneas were thoroughly rinsed. The opacity of the corneas was determined directly after treatment and the permeability of the corneas was determined after a 90 minutes incubation period with sodium fluorescein.

Results and discussion

In vitro

Results

Results 1

Irritation parameter:

cornea opacity score

Run / experiment:

Dilithium tetraborate - first experiment

Value:

2.8

Negative controls validity:

valid

Positive controls validity:

valid

Results 2

Irritation parameter:

cornea opacity score

Run / experiment:

Dilithium tetraborate - second experiment

Value:

-1.3

Negative controls validity:

valid

Positive controls validity:

valid

Results 3

Irritation parameter:

in vitro irritation score

Run / experiment:

Dilithium tetraborate - first experiment

Value:

37

Negative controls validity:

valid

Positive controls validity:

valid

Results 4

Irritation parameter:

in vitro irritation score

Run / experiment:

Dilithium tetraborate - second experiment

Value:

14

Negative controls validity:

valid

Positive controls validity:

valid

Results 5

Irritation parameter:

fluorescein retention score

Run / experiment:

Dilithium tetraborate - first experiment

Value:

2.297

Negative controls validity:

valid

Positive controls validity:

valid

Results 6

Irritation parameter:

fluorescein retention score

Run / experiment:

Dilithium tetraborate - second experiment

Value:

0.99

Negative controls validity:

valid

Positive controls validity:

valid

Other effects / acceptance of results:

The corneas treated with dilithium tetraborate showed opacity values ranging from 2.0 to 3.9 and permeability values ranging from 0.317 to 3.903. The corneas were translucent after the 240 minutes of treatment with dilithium tetraborate. No pH effect of the test item was observed on the rinsing medium. Hence, the in vitro irritancy scores ranged from 7.4 to 60 after 240 minutes of treatment with Dilithium tetraborate.Since the results for dilithium tetraborate were spread over 2 categories (7.4, 60 and 44, respectively), the test was inconclusive and a repeat experiment was performed. The corneas treated with dilithium tetraborate showed opacity values ranging from -1.8 to -1.0 and permeability values ranging from 0.065 to 2.642. The corneas were partly translucent after the 240 minutes of treatment with dilithium tetraborate. A pH effect of the test item was observed on the rinsing medium, the corneas were rinsed until no colour change of the medium was observed. Hence, the in vitro irritancy scores ranged from -0.8 to 39 after 240 minutes of treatment with dilithium tetraborate. Since both tests provided inconclusive results, no conclusion can be drawn for eye irritation or serious eye damage.

Any other information on results incl. tables

First experiment

Treatment	Mean Opacity	Mean Permeability	Mean In vitro Irritation Score^1, 2
Negative control	4.0	0.022	4.3
Positive control	116	1.744	143
Dilithium tetraborate	2.8	2.297	37

¹  Calculated using the negative control mean opacity and mean permeability values for the positive control and test item.

²  In vitro irritancy score (IVIS) = mean opacity value + (15 x mean OD490 value).

 

Second experiment

Treatment	Mean Opacity	Mean Permeability	Mean In vitro Irritation Score^1, 2
Negative control	2.5	0.021	2.8
Positive control	123	1.758	150
Dilithium tetraborate	-1.3	0.990	14

¹    Calculated using the negative control mean opacity and mean permeability values for the positive control and test item.

²    In vitro irritancy score (IVIS) = mean opacity value + (15 x mean OD490 value).

 

Applicant's summary and conclusion

Interpretation of results:

study cannot be used for classification

Conclusions:

Both tests (experiment 1 & 2) provided inconclusive results, and therefore no conclusion can be drawn for eye irritation or serious eye damage.

Executive summary:

In a well conducted Bovine Corneal Opacity and Permeability Assay (BCOP), dilithium tetraborate was topically applied to the epithelium of the bovine cornea for 4 hours. The non-surfactant solid test item was applied neat by direct application to the surface of the cornea. After exposure the corneas were thoroughly rinsed. The opacity of the corneas was determined directly after treatment and the permeability of the corneas was determined after a 90 minutes incubation period with sodium fluorescein. The mean in vitro irritancy score was 37 and 14 after 240 minutes of treatment with the test item in the first and second experiment, respectively. The results for dilithium tetraborate were spread over 2 categories in both experiments. Because both tests provided inconclusive results, no conclusion can be drawn for eye irritation or serious eye damage. A further study on rabbits was therefore conducted (van Sas, 2017).