2-morpholinoethanesulphonic acid

Eye irritation

Administrative data

Endpoint:

eye irritation: in vitro / ex vivo

Type of information:

experimental study

Adequacy of study:

key study

Study period:

2016-06-21

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

Test guideline 1

Qualifier:

according to guideline

Guideline:

OECD Guideline 438 (Isolated Chicken Eye Test Method for Identifying i) Chemicals Inducing Serious Eye Damage and ii) Chemicals Not Requiring Classification for Eye Irritation or Serious Eye Damage)

Version / remarks:

2013

Deviations:

no

Test guideline 2

Qualifier:

according to guideline

Guideline:

EU method B.48 (Isolated chicken eye test method for identifying occular corrosives and severe irritants)

Version / remarks:

2010

Deviations:

no

GLP compliance:

yes (incl. QA statement)

Test material

Test material information

Constituent 1

Reference substance name:

2-(4-morpholinyl)ethansulfonic acid hydrate

Cas Number:

1266615-59-1

Molecular formula:

C6H13NO4S * xH2O

IUPAC Name:

2-(4-morpholinyl)ethansulfonic acid hydrate

Test material form:

solid: particulate/powder

Test animals / tissue source

Species:

chicken

Strain:

other: ROSS 308

Details on test animals or tissues and environmental conditions:

SOURCE OF COLLECTED EYES
- Source: TARAVIS KFT. 9600 Sárvár, Rábasömjéni út 129. Hungary
- Storage, temperature and transport conditions of ocular tissue (e.g. transport time, transport media and temperature, and other conditions):
The heads were transported to Toxi-Coop ZRT. at the earliest convenience for use approximately within 2 hours from collection. The ambient temperature was optimal (19.3 ºC to 20.2 ºC) during the transport. All eyes used in the assay were from the same groups of eyes collected on one specific day. After collection, the heads were inspected for appropriate quality and wrapped with paper moistened with saline, then placed in a plastic box that can be closed (4-5 heads/box).
- Time interval prior to initiating testing: If the selected eyes were appropriate for the test, acclimatization started and was conducted for approximately 45 to 60 minutes.
- indication of any existing defects or lesions in ocular tissue samples:
After removing the head from the plastic box, it was put on soft paper. The eyelids were carefully cut away with scissors, avoiding damaging the cornea. One small drop of fluorescein solution 2 (w/v) % was applied onto the cornea surface for a few seconds and subsequently rinsed off with 20 mL isotonic saline. Then the fluorescein-treated cornea was examined with hand-held slit lamp or slit lamp microscope, with the eye in the head, to ensure that the cornea was not damaged. If the cornea was in good condition, the eyeball was carefully removed from the orbit. The cornea thickness was measured using the depth measuring device on the slit lamp microscope (Haag-Streit BQ 900) with the slit-width set at 9½, equalling 0.095 mm. Any eye with cornea thickness deviating more than 10 % from the mean value for all eyes, or eyes that showed any other signs of damage, were rejected and replaced.
- Indication of any antibiotics used: none

Test system

Vehicle:

unchanged (no vehicle)

Controls:

yes, concurrent positive control

yes, concurrent negative control

Amount / concentration applied:

TEST MATERIAL
- Amount(s) applied (volume or weight with unit): 0.03 g (per eye)

CONTROLS
- Amount(s) applied (volume or weight with unit): 0.03g imidazole; 30 µL NaCl (in saline)

Duration of treatment / exposure:

10 sec

Duration of post- treatment incubation (in vitro):

4 hours

Number of animals or in vitro replicates:

3 eyes (test substance and positive control)
1 eye (negative control)

Details on study design:

SELECTION AND PREPARATION OF ISOLATED EYES:
With the eyes still in the chicken heads, eyelids were carefully cut away with scissors from the chicken eyes. One small drop of fluorescein solution 2% (w/v) was applied onto the cornea surface for a few seconds and then rinsed off with 20 mL isotonic saline. The fluorescein-treated cornea was examined with a hand-held slit lamp or a slit lamp microscope. If the cornea was in good condition, the eyeball was carefully removed from the orbit by holding the nictitating membrane with a surgical forceps, while cutting the eye muscles with bent scissors without cutting off the optical nerve too short. The procedure avoided pressure on the eye, which may lead to corneal opacity. Once removed from the orbit, the eye was placed onto damp paper and the nictitating membrane was cut away with other connective tissue. The prepared eyes were kept on the wet papers in a closed box to maintain the appropriate humidity.

EQUILIBRATION AND BASELINE RECORDINGS
The prepared eye was placed in a clamp with the cornea positioned vertically with the eye in the correct relative position (same position as in the chicken head), again avoiding too much pressure on the eye. Because of the relatively firm sclera of the chicken eyeball, only slight pressure was applied to fix the eye properly. The clamp was transferred to a chamber of the superfusion apparatus. The clamp holding the eye was positioned in such a way that the entire cornea was supplied with saline solution dripping from a stainless steel tube, at a rate of approx. 3 to 5 drops/min. The door of the chamber was closed, except for manipulations and examination, to maintain temperature and humidity.
Eyes selected for testing were again examined with the slit lamp microscope. Eyes with a high baseline fluorescein staining (i.e. > 0.5) or corneal opacity score (i.e. > 0.5) were rejected.

NUMBER OF REPLICATES: 3

NEGATIVE CONTROL USED: NaCl in saline (9 g/L) (n=1)

SOLVENT CONTROL USED: not applicable

POSITIVE CONTROL USED: Imidazole (n=3)

APPLICATION DOSE AND EXPOSURE TIME: 0.03 g per eye for 10 seconds

OBSERVATION PERIOD: 4 hours

REMOVAL OF TEST SUBSTANCE
- Volume and washing procedure after exposure period: Thorough rinsing with approx. 20 mL saline solution at ambient temperature
- Indicate any deviation from test procedure in the Guideline: none

METHODS FOR MEASURED ENDPOINTS:
- Corneal opacity: Opacity scores ranging from 0 (no opacity) to 4 (complete opacity; iris invisible) according to the test guideline were measured at all time points
- Damage to epithelium based on fluorescein retention: Fluorescein retention scores ranging from 0 - 3 according to the test guideline were measured at 0 and 30 min.
- Swelling: measured with optical pachymeter on a slit-lamp microscope; slit-width setting: Cornea thickness was measured using the depth measuring device on the slit lamp microscope (Haag-Strei BQ 900) with the slit-width set at 9.5, i.e. 0.095mm.
- Macroscopic morphological damage to the surface: not applicable
- Others (e.g, histopathology): not performed

SCORING SYSTEM:
- Mean corneal swelling (%): according to TG
- Mean maximum opacity score: according to TG
- Mean fluorescein retention score at 30 minutes post-treatment: according to TG

DECISION CRITERIA: Decision criteria as indicated in the TG were used.

Results and discussion

In vitro

Results

Results 1

Irritation parameter:

percent corneal swelling

Remarks:

240 min

Run / experiment:

1st experiment

Value:

2

Vehicle controls validity:

not applicable

Negative controls validity:

valid

Remarks:

2

Positive controls validity:

valid

Remarks:

30

Results 2

Irritation parameter:

cornea opacity score

Run / experiment:

1st experiment

Value:

0.2

Vehicle controls validity:

not applicable

Negative controls validity:

valid

Remarks:

0.5

Positive controls validity:

valid

Remarks:

4

Results 3

Irritation parameter:

fluorescein leakage

Run / experiment:

1st experiment

Value:

0

Vehicle controls validity:

not applicable

Negative controls validity:

valid

Remarks:

0

Positive controls validity:

valid

Remarks:

3

Other effects / acceptance of results:

OTHER EFFECTS:
- Visible damage on test system: none

DEMONSTRATION OF TECHNICAL PROFICIENCY: no

ACCEPTANCE OF RESULTS:
- Acceptance criteria met for negative control: yes
- Acceptance criteria met for positive control: yes
- Range of historical values if different from the ones specified in the test guideline: not applicable

Applicant's summary and conclusion

Interpretation of results:

GHS criteria not met

Conclusions:

In this in vitro eye corrosive and severe irritant study, using the Isolated Chicken Eye model, no ocular corrosion or severe irritation potential was observed. The overall ICE score was 3xI.

Executive summary:

A study according OECD TG 438 was performed to evaluate the potential ocular corrosivity and irritancy of the test item by its ability to induce toxicity in enucleated chicken eyes. This test identifies chemicals either inducing "serious eye damage", or not requiring classification for eye irritation or serious eye damage according to the GHS. The test item was applied in a single dose (30 mg/eye) onto the cornea of isolated chicken eyes and rinsed after 10 seconds with saline. Tested corneas were evaluated pre-treatment and at approximately 30, 75, 120, 180, and 240 minutes after the post-treatment rinse. The endpoints evaluated were corneal opacity, swelling, fluorescein retention, and morphological effects. All of the endpoints, with the exception of fluorescein retention (which was determined only at pre-treatment and 30 minutes after test substance exposure) were determined at each of the above time points.

The test item and Imidazole (positive control) were ground before use in the study. Test item and positive control were applied in an amount of 30 mg/eye by powdering the entire surface of the cornea attempting to cover the cornea surface uniformly with the test substance or positive control. Three test item treated eyes and three positive control eyes were used in this study.

One negative control eye was treated with 30μL saline solution.

After an exposure period of 10 seconds from the end of the application the cornea surface was rinsed thoroughly with approximately 20 mL saline solution at ambient temperature and this procedure was repeated for each eye.

In this ICET, the test item did not cause ocular corrosion or severe irritation in the enucleated chicken eyes. The overall ICE class was 3xI.

Positive and negative controls showed the expected results. The experiment was considered to be valid.