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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
Reliability:
1 (reliable without restriction)
Rationale for reliability incl. deficiencies:
guideline study

Data source

Reference
Reference Type:
study report
Title:
Unnamed
Year:
2015
Report Date:
2015

Materials and methods

Test guideline
Qualifier:
according to
Guideline:
OECD Guideline 437 (Bovine Corneal Opacity and Permeability Test Method for Identifying i) Chemicals Inducing Serious Eye Damage and ii) Chemicals Not Requiring Classification for Eye Irritation or Serious Eye Damage)
GLP compliance:
yes (incl. certificate)

Test material

Reference
Name:
Unnamed
Type:
Constituent
Test material form:
solid: crystalline

Test animals / tissue source

Species:
cattle
Strain:
not specified
Details on test animals or tissues and environmental conditions:
The bovine eyes, in a Hank's Balanced Salt Solution with penicillin-streptomycin, were received from Spear Products on 5 Nov 2015 and transported to MB Research in a refrigerated container.

Test system

Vehicle:
physiological saline
Controls:
yes, concurrent positive control
yes, concurrent negative control
Amount / concentration applied:
A volume of 0.75 ml of 20% imidazole in saline, MEM or 20% suspension of test article in saline was applied to the epithelium of each of the three positive controls, three negative controls or three test article-treated corneas in a manner, which ensured the entire cornea was covered. All corneas were dosed via the closed-chamber method.
Duration of treatment / exposure:
All holders and corneas were placed in a horizontal position (anterior side up) in the 32ºC (± 1º) incubator. After 10 (± 1) minutes, the test article, imidazole or MEM solution was removed from the epithelium of the
cornea and anterior chamber of the holder by washing with MEM solution containing phenol red. A final rinse was made with MEM without phenol red. The anterior and posterior chambers of the holders were
refilled with fresh MEM solution. Opacity measurements were made following the 10-minute exposure and MEM solution refill.
All corneas were incubated at 32ºC (± 1º) for an additional two hours at which time the MEM solution in the anterior and posterior chambers was removed and the holders refilled with fresh MEM solution.
A measurement of opacity was taken with each treated cornea compared to the blank supplied with the
OP-KIT.
This reading was used in the final IVIS calculations. Immediately following the two-hour opacity measurement, the MEM solution was removed from the anterior chamber and replaced with 1.0 ml of 0.4% sodium fluorescein solution
in Dulbecco's Phosphate Buffered Saline (PBS). Each holder was returned to the 32ºC (±1º) incubator in a horizontal position (anterior side up) ensuring contact of the fluorescein with the cornea.
After 90 (± 5) minutes, the fluid from the posterior chamber was removed and the amount of dye, which passed through the cornea (permeability), was measured as the optical density at 490 nm by a
spectrophotometer. A 1:1000 dilution of the fluorescein was prepared and measured in the spectrophotometer as a measure of consistency.
Observation period (in vivo):
Not applicable
Duration of post- treatment incubation (in vitro):
See Details on study design
Number of animals or in vitro replicates:
Not applicable
Details on study design:
The eyes were examined prior to use on the day of dosing. Any eye with a cornea exhibiting evidence of vascularization, pigmentation, opacity or scratches was discarded.
Corneas from eyes that were free of defects were dissected from the surrounding tissues. A 2-3 mm rim of sclera was left attached to each cornea. The corneas were then placed in a container of fresh HBSS.
The dissected corneas were mounted in specially designed holders that were separated into anterior and posterior chambers and filled separately. Each cornea was mounted allowing the epithelium of the cornea to project into the anterior chamber. The posterior chamber was filled with MEM solution ensuring contact with the endothelium. The anterior chamber was filled with MEM solution, ensuring contact with the epithelium. Each cornea was visually inspected again to ensure there were no defects.
The entire holder was incubated at 32ºC (± 1º) and allowed to equilibrate for at least one hour but not longer than two hours.
A pre-exposure determination of opacity was made for each cornea by measuring each against the blank supplied with the opacitometer. Any cornea with a value greater than 7 units was discarded.
Following the pretest observations, the MEM solution was removed from the anterior chamber. A volume of 0.75 ml of ethanol, MEM or test article was applied to the epithelium of each of the three positive controls, three negative controls or three test article-treated corneas in a manner, which ensured the entire cornea was covered. The closed-chamber method of dose administration was used.
All holders and corneas were placed in a horizontal position (anterior side up) in the 32ºC (± 1º) incubator. After 10 (± 1) minutes, the test article, ethanol or MEM solution was removed from the epithelium of the cornea and anterior chamber of the holder by washing with MEM solution containing phenol red. A final rinse was made with MEM without phenol red. The anterior and posterior chambers of the holders were refilled with fresh MEM solution. Opacity measurements were made following the 10-minute exposure and MEM solution refill.
All corneas were incubated at 32ºC (± 1º) for an additional two hours at which time the MEM solution in the anterior and posterior chambers was removed and the holders refilled with fresh MEM solution. A measurement of opacity was taken with each treated cornea compared to the blank supplied with the
OP-KIT. This reading was used in the final IVIS calculations.
Immediately following the two-hour opacity measurement, the MEM solution was removed from the anterior chamber and replaced with 1.0 ml of 0.4% sodium fluorescein solution in Dulbecco's Phosphate Buffered Saline (PBS). Each holder was returned to the 32ºC (±1º) incubator in a horizontal position (anterior side up) ensuring contact of the fluorescein with the cornea.
After 90 (± 5) minutes, the fluid from the posterior chamber was removed and the amount of dye, which passed through the cornea (permeability), was measured as the optical density at 490 nm by a spectrophotometer. A 1:1000 dilution of the fluorescein was prepared and measured in the spectrophotometer as a measure of consistency.
Data analysis
Individual corrected opacity scores were calculated by subtracting the pretest score from the ten-minute and two-hour scores. Corrected mean opacity scores were calculated by averaging the individual two-hour corrected opacity scores for a given dose group and subtracting the mean opacity score for the negative control group. A corrected mean opacity score was not calculated for the negative control, rather only the mean of the individual two-hour corrected opacity scores were calculated (with no subtraction of mean opacity score for negative control.)
Individual corrected optical densities were calculated by subtracting the mean optical density for the negative control group from the individual optical density values. Individual corrected optical densities were not calculated for the negative control group. Corrected mean optical densities were calculated by averaging the individual corrected optical density values for a given dose group. A corrected mean optical density was not calculated for the negative control, rather only the mean of the individual optical densities was calculated.
The In Vitro Irritancy Score (IVIS) for the test article and Vehicle control was calculated by adding the corrected mean opacity score to fifteen times the corrected mean optical density, as shown by the equation below. The calculation to obtain an IVIS for the positive control was performed in the same manner as the test article.
In Vitro Irritancy Score (IVIS) = Corrected Mean Opacity Score + (15 x Corrected Mean Optical Density Score)
The calculation to obtain an IVIS for the negative control was performed by adding the mean opacity score to fifteen times the mean optical density, as shown by the equation below.
In Vitro Irritancy Score (IVIS) = Mean Opacity Score + (15 x Mean Optical Density Score)

Based on the IVIS score, the test article was classified according to the prediction model described in DB-ALM Protocol No. 1271, a modification of the prediction model suggested by Gautheron, et al. (1994). Results from test situations should be compared to known materials tested under similar conditions. This classification system is the most consistent with recent regulatory reviews of the assay performance.
IVIS CLASSIFICATION
0 to 3 Non-Irritant
3.1 to 25 Mild Eye Irritant
25.1 to 55 Moderate Eye Irritant
55.1 and above Severe/Corrosive Eye Irritant
OECD Guideline #437 defines a substance that produces an IVIS of > 55 as Category 1, a substance that causes “Serious eye damage.”
IVIS UN GHS2
≤ 3 No Category
>3 to ≤55 No prediction can be made
>55 Category 1
The assay was accepted because the positive control had an IVIS that fell between two standard deviations of the historical mean.

Results and discussion

In vitro

Resultsopen allclose all
Irritation parameter:
in vitro irritation score
Run / experiment:
Mean value for 3 experiments
Value:
64.7
Vehicle controls valid:
yes
Negative controls valid:
yes
Positive controls valid:
yes
Irritation parameter:
cornea opacity score
Run / experiment:
Mean of 3 experiments
Value:
64.7
Vehicle controls valid:
yes
Negative controls valid:
yes
Positive controls valid:
yes

Applicant's summary and conclusion

Interpretation of results:
Category 1 (irreversible effects on the eye) based on GHS criteria
Conclusions:
Based on an In Vitro Irritation Score of greater than 55, and as defined in OECD Guideline 437, the test article 2-hydroxyethyliminodi(acetic acid) is in UN GHS Category 1.
According to EURL ECVAM DB-ALM Protocol No. 127, 2-hydroxyethyliminodi(acetic acid) is considered to be a severe/corrosive eye irritant
Executive summary:

Based on an In Vitro Irritation Score of greater than 55, and as defined in OECD Guideline 437, the test article 2-hydroxyethyliminodi(acetic acid) is in UN GHS Category 1.

According to EURL ECVAM DB-ALM Protocol No. 127, 2-hydroxyethyliminodi(acetic acid) is considered to be a severe/corrosive eye irritant