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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:
key study
Study period:
26 October 2017 - 09 March 2018
Reliability:
1 (reliable without restriction)
Rationale for reliability incl. deficiencies:
guideline study

Data source

Reference
Reference Type:
study report
Title:
Unnamed
Year:
2018
Report Date:
2018

Materials and methods

Test guideline
Qualifier:
according to
Guideline:
OECD Guideline 437 (Bovine Corneal Opacity and Permeability Test Method for Identifying Ocular Corrosives and Severe Irritants)
Deviations:
no
GLP compliance:
yes (incl. certificate)

Test material

Reference
Name:
Unnamed
Type:
Constituent
Test material form:
solid: particulate/powder
Details on test material:
Test item: Black DB
Appearance: black powder

Test animals / tissue source

Species:
cattle
Strain:
not specified
Details on test animals or tissues and environmental conditions:
- Source: Schlachthof Aschaffenburg, 63739 Aschaffenburg, Germany
- Age at study initiation: at least 9 month old donor cattle

Test system

Vehicle:
physiological saline
Controls:
yes, concurrent vehicle
yes, concurrent positive control
Amount / concentration applied:
The test item was tested as a 20% suspension (w/v) in saline using sonication for 10 minutes. The pH value of the suspension prior to application was 7.69.
Duration of treatment / exposure:
240 minutes
Number of animals or in vitro replicates:
3 corneae per group (test item, negative control, positive control)
Details on study design:
Three corneas were exposed to each 0.75 mL of a 20% (w/v) suspension of the stest item in physiological saline for 240 minutes.
After treatment the test item suspension was rinsed off the corneas and the corneas' opacity was determined. In a second step the permeability of the corneas was determined photometrically after 90 minutes treatment with fluorescein solution.

Opacity measurement
The opacitometer determines changes in the light transmission passing through the corneae, and displays a numerical opacity value. This value was recorded in a table. The opacitometer OP_KiT opacitometer (Electro Design, 63-Riom France) was calibrated as described in the manual and the opacity of each of the corneae was determined by reading each holder placed in the photoreceptor compartment for treated cornea.

For equilibration and prior to application of the test item or controls, the corneae in the holder were incubated in a vertical position for about one hour at 32 ± 1 °C in a water-bath. At the end of the incubation period, the basal opacity was determined (t0). After exposure of the corneae to the test groups, after rinsing and further incubation of the corneae for two hours, the opacity value was determined again (t240).

Permeability Determination
Following to the opacity readings, the permeability was measured as an indication of the integrity of the epithelial cell sheets. After the final opacity measurement was performed, the incubation medium will be removed from the anterior compartment and replaced by 1 mL of a 0.5% (w/v) sodium fluorescein solution in HBSS. Corneae were incubated again in a horizontal position for 90 ± 10 minutes in a water-bath at 32 ± 1 °C. Incubation medium from the posterior compartment were removed, well mixed and transferred into a 96 well plate and the optical density at 490 nm (OD490) was determined with a spectrophotometer (Versamax® Molecular Devices). The absorbance values will be determined using the software SoftMax Pro Enterprise (version 4.7.1).

DATA EVALUATION
Opacity
The change of opacity value of each treated cornea or positive and negative control corneae is calculated by subtracting the initial basal opacity from the post treatment opacity reading (t240 – t0), for each individual cornea.
The average change in opacity of the negative control corneae is calculated and this value is subtracted from the change in opacity of each treated cornea or positive control to obtain a corrected opacity.

Permeability
The corrected OD490 value of each cornea treated with positive control and test item is calculated by subtracting the average negative control cornea value from the original permeability value for each cornea.

IVIS Calculation
The following formula is used to determine the IVIS of the negative control:
IVIS = opacity value + (15 x OD490 value)
The following formula is used to determine the IVIS of the positive control and the test item:
IVIS = (opacity value – opacity value mean negative control) + (15 x corrected OD490 value)
The mean IVIS value of each treated group is calculated from the IVIS values.
Depending on the score obtained, the test item is classified into the following category according to OECD guideline 437:

IVIS: In vitro Irritancy Score (according to OECD 437):

≤ 3 No Category (according to GHS)
> 3; ≤ 55 No prediction can be made
> 55 Serious eye damaging according to CLP/EPA/GHS (Cat 1)


Criteria for Determination of a Valid Test

The test will be acceptable if
• the positive control gives an IVIS that falls within two standard deviations of the current historical mean (updated every three months), and if
• the negative control responses result in opacity and permeability values that are less than the established upper limits for background opacity and permeability values for bovine corneae treated with the respective negative control.

Results and discussion

In vitro

Resultsopen allclose all
Irritation parameter:
in vitro irritation score
Run / experiment:
mean
Value:
8.6
Vehicle controls validity:
valid
Negative controls validity:
not examined
Positive controls validity:
valid
Irritation parameter:
in vitro irritation score
Remarks:
Replicate 1
Run / experiment:
1
Value:
10.75
Vehicle controls validity:
valid
Negative controls validity:
not examined
Positive controls validity:
valid
Irritation parameter:
in vitro irritation score
Remarks:
Replicate 2
Run / experiment:
1
Value:
12.75
Vehicle controls validity:
valid
Negative controls validity:
not examined
Positive controls validity:
valid
Irritation parameter:
in vitro irritation score
Remarks:
Replicate 3
Run / experiment:
1
Value:
2.31
Vehicle controls validity:
valid
Negative controls validity:
not examined
Positive controls validity:
valid

Any other information on results incl. tables

Results after 240 Minutes Treatment Time


Test Group

Opacity value = Difference (t240-t0) of Opacity

Permeability at 490 nm (OD490)

IVIS

Mean IVIS

Proposed in vitro Irritancy Score

Standard Deviation of in vitro Score

 

 

Mean

 

Mean

 

 

 

 

Negative Control

-2

-1.00

0.082

0.077

-0.77

0.15

Not categorized

1.90

-2

0.059

-1.12

1

0.089

2.34

Positive Control

213.00*

0.006*

213.10

164.26

Category 1

42.44

135.00*

0.090*

136.36

143.00*

0.021*

143.32

Black DB

11.00*

-0.017*

10.75

8.60

No prediction can be made

5.54

13.00*

-0.017*

12.75

2.00*

0.020*

2.31

*corrected values

Applicant's summary and conclusion

Interpretation of results:
other: not Category 1 (irreversible effects on the eye) based on GHS criteria
Conclusions:
Based on the results of the OECD 437 study, the test item is not requiring classification for eye damaging potential (UN GHS Category 1). No prediction can be made if the test item is requiring classification for eye irritation (UN GHS Category 2) or if the test item is not requiring classification (UN GHS no Category).
Executive summary:

This in vitro study was performed to assess the corneal damage potential of the test item by means of the BCOP assay using fresh bovine corneas. After a first opacity measurement of the fresh bovine corneas (t0), the 20% (w/v) suspension in saline of the test item Black DB, the positive, and the negative controls were applied to the different corneas and incubated for 240 minutes at 32± 1 °C. After the incubation phase, the test item as well as the positive and the negative controls were each rinsed from the corneas and opacity was measured again (t240). After the opacity measurements, permeability of the corneas was determined by measuring spectrophotometrically the transfer of sodium fluorescein after incubation in a horizontal position for 90 minutes at 32 ± 1 °C.

For the negative control (saline) an increase of neither opacity nor permeability of the corneas could be observed (mean IVIS = 0.15). The negative control responses resulted in opacity and permeability values that are less than the established upper limits for background opacity and permeability values for bovine corneas treated with the respective negative control. Therefore the acceptability criteria were fulfilled. The positive control (10% (w/v) benzalkonium chloride in saline) showed clear opacity and distinctive permeability of the corneas (mean IVIS = 164.26) corresponding to a classification as serious eye damaging (CLP/EPA/GHS (Cat 1)). The positive control did not met the acceptance criteria of the assay since the mean IVIS is higher than twofold standard deviation of the upper limit of historical established boundaries. However, the raw data show that the IVIS of one cornea out of three of the positive control revealed a higher value compared to the other two corneas which values are in an acceptable range. This single cornea can be declared as outlier. Therefore this deviation has no impact on the validity or the outcome of the study. The Test Item was tested as suspension. Relative to the negative control, the test item caused an increase of the corneal opacity. The calculated mean IVIS was 8.60 (threshold for serious eye damage: IVIS > 55). According to OECD 437, the test item is not requiring classification for eye damaging potential (UN GHS Category 1). No prediction can be made if the test item is requiring classification for eye irritation (UN GHS Category 2) or if the test item is not requiring classification (UN GHS no Category).