L-Tyrosine, 3,5-dinitro-

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:

2018

Materials and methods

Test guideline

Test guideline 1

Qualifier:

according to guideline

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)

Test guideline 2

Qualifier:

according to guideline

Guideline:

EU method B.47 (Bovine corneal opacity and permeability test method for identifying ocular corrosives and severe irritants)

GLP compliance:

yes (incl. QA statement)

Test material

Test material information

1

Reference substance name:

L-Tyrosine, 3,5-dinitro-

Cas Number:

17360-11-1

Molecular formula:

C9H9N3O7

IUPAC Name:

L-Tyrosine, 3,5-dinitro-

Test material form:

solid

Test system

Vehicle:

Hank's balanced salt solution

Controls:

yes, concurrent vehicle

yes, concurrent positive control

Details on study design:

Method Description
After the initial incubation, the medium was changed and the baseline opacity for each cornea was recorded. None of the corneas showed tissue damage; therefore, all corneas were used. For each treatment group (negative control solution, test item and positive control), three replicates were used. After removal of the pre-incubation medium (cMEM without phenol red), 750 µL of negative control solution, 750 µL of test item suspension and 750 µL of positive control solution were applied to each replicate.
According to the characteristics of the test item, the following treatment procedure was performed:

Open Chamber Method
In order to apply the test item, the nut was unscrewed to remove the glass disc.
750 µL of the test item were tested as suspension at 20% concentration in HBSS. The test item was given directly on the epithelium in such a manner that the cornea was cov-ered with test item.
Exposure time on the corneas was 4 hours at 32 ± 1 °C. After thorough rinsing with cMEM with phenol red and final rinsing with cMEM without phenol red, both chambers were filled with cMEM without phenol red, and the final opacity value of each cornea was recorded.

Permeability Test
After the recording of the final opacity value, the cMEM without phenol red was removed from the front chamber, and 1 mL sodium fluorescein solution was added to the front chamber for the detection of permeability of the corneas.
For the open chamber method, a sodium fluorescein solution with a concentration of 5 mg/mL was used.
The chambers were then closed again and incubated for 90 minutes at 32 ± 1 °C. After incubation, the content of the posterior chamber was thoroughly mixed. Then, its optical density at 492 nm was measured with the microtiter plate photometer.

Results and discussion

In vitro

Results

Results 1

Irritation parameter:

in vitro irritation score

Remarks:

IVIS (In Vitro Irritancy Score)

Run / experiment:

1st replicate

Value:

154.65

Vehicle controls validity:

valid

Negative controls validity:

valid

Positive controls validity:

valid

Results 2

Irritation parameter:

in vitro irritation score

Remarks:

IVIS (In Vitro Irritancy Score)

Run / experiment:

2nd replicate

Value:

135.27

Vehicle controls validity:

valid

Negative controls validity:

valid

Positive controls validity:

valid

Results 3

Irritation parameter:

in vitro irritation score

Remarks:

IVIS (In Vitro Irritancy Score)

Run / experiment:

3nd replicate

Value:

144.83

Vehicle controls validity:

valid

Negative controls validity:

valid

Positive controls validity:

valid

Results 4

Irritation parameter:

in vitro irritation score

Remarks:

IVIS (In Vitro Irritancy Score)

Run / experiment:

mean value

Value:

144.92

Vehicle controls validity:

valid

Negative controls validity:

valid

Positive controls validity:

valid

Other effects / acceptance of results:

According to the guideline, the test is considered as valid if the positive control causes an IVIS that falls within two standard deviations of the current historical mean.
The mean IVIS of the negative control has to show an IVIS ≤ 3.

Applicant's summary and conclusion

Interpretation of results:

Category 1 (irreversible effects on the eye) based on GHS criteria

Conclusions:

According to OECD Guideline no. 437 (Oct. 2017), a substance with an IVIS > 55 induces serious eye damage, that should be classified as UN GHS Category I.
In the negative control, no signs of eye irritation were observed.
The positive control induced serious eye damage, which would be classified as GHS cate-gory I.
The test item L-Tyrosine, 3,5-dinitro- (wet product) induced serious eye damage on the cornea of the bovine eye. The calculated IVIS is 144.92.
The experiment is considered as sufficient for the classification of the test item, because all three replicates of the test item lead to the same assessment for the test item.

Executive summary:

Bovine corneas were used. They were collected from slaughtered cattle that were between 12 and 60 months old.

The test itemL-Tyrosine, 3,5-dinitro- (wet product)was brought onto the cornea of a bovine eye which had been previously incubated with cMEM without phenol red at 32 ± 1 °C for 1  hour and whose opacity had been measured.

The test item was incubated on the cornea for 4 hours at 32 ± 1 °C. After removal of the test item, opacity and permeability values were measured.

Hank’s Balanced Salt Solution (HBSS) was used as negative control. The negative control showed no irritating effect on the cornea and the calculated IVIS (In VitroIrritancy Score) is 1.68.

20% imidazole solution was used as positive control. The positive control induced serious eye damage on the cornea and was within two standard deviations of the current historical mean. The calculated IVIS is 98.54.