Butyl 3-mercaptopropionate

Eye irritation

Administrative data

Endpoint:

eye irritation: in vitro / ex vivo

Type of information:

experimental study

Adequacy of study:

key study

Study period:

19 May 2022

Reliability:

1 (reliable without restriction)

Rationale for reliability incl. deficiencies:

guideline study

Data source

Reference

Reference Type:

study report

Title:

Unnamed

Year:

2022

Report date:

2022

Materials and methods

Test guideline

Test guideline 1

Qualifier:

according to guideline

Guideline:

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

Version / remarks:

dated 14 February 2017

Deviations:

no

Test guideline 2

Qualifier:

according to guideline

Guideline:

OECD Guideline 438 (Isolated Chicken Eye Test Method for Identifying Ocular Corrosives and Severe Irritants)

Version / remarks:

25 June 2018

Deviations:

no

GLP compliance:

yes (incl. QA statement)

Test material

Test material information

Constituent 1

Reference substance name:

Butyl 3-mercaptopropionate

EC Number:

240-343-5

EC Name:

Butyl 3-mercaptopropionate

Cas Number:

16215-21-7

Molecular formula:

C7H14O2S

IUPAC Name:

butyl 3-sulfanylpropanoate

Test animals / tissue source

Species:

chicken

Strain:

other: COBB 500

Details on test animals or tissues and environmental conditions:

Source: TARAVIS KFT. 9600 Sárvár, Rábasömjéni utca 129. Hungary
Only the eyes of healthy animals considered suitable for entry into the human food chain were used Head collection was performed by a slaughter house technician. Heads were removed immediately after sedation of the chickens (sedation was performed by electric current). 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 (20.6 ºC to 21.2 ºC) during the transport. All eyes used in the assay were from the same groups of eyes collected on one specific day.
Cornea integrity was checked by applying one small drop of fluorescein 2 % (w/v) solution 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 a 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.

Test system

Vehicle:

unchanged (no vehicle)

Controls:

yes, concurrent positive control

yes, concurrent negative control

Amount / concentration applied:

0.03 g or 30 μL per cornea

Duration of treatment / exposure:

exposure period of 10 seconds

Duration of post- treatment incubation (in vitro):

The control and test eyes were evaluated pre-treatment and at approximately 30, 75, 120, 180 and 240 minutes after the post-treatment rinse. Minor variations within ± 5 minutes were considered acceptable.

Number of animals or in vitro replicates:

3 (positive control + test item), 1 (negative control)

Details on study design:

SELECTION AND PREPARATION OF ISOLATED EYES

EQUILIBRATION AND BASELINE RECORDINGS
- acclimatisation for approximately 45 to 60 minutes at 32 ± 1.5 °C
- At the end of the acclimatization period, a zero reference measurement was recorded for cornea thickness and opacity to serve as a baseline (t=0) for each individual eye. The cornea thickness of the eyes should not change by more than ±5-7 % within approximately 45 to 60 minutes before the start of application. Changes in thickness were not observed in the eyes. Following the equilibration period, the fluorescein retention was measured. Baseline values were required to evaluate any potential test item related effects after treatment. None of the eyes were discarded as no eye was considered unsuitable after the baseline assessment.


REMOVAL OF TEST SUBSTANCE
- rinsed thoroughly with 20 mL saline solution at ambient temperature

SCORING SYSTEM:
- Mean corneal swelling (%)
For the calculation of Maximum Swelling, small negative numbers for swelling (0 to -5%) following application are counted as zero. Large negative numbers (> -12 %) are probably due to erosion and indicate a severe effect (scored as class IV). Cases of values of -5 % to -12 % are evaluated on a case by case basis but in the absence of other findings do not indicate a severe effect.
- Mean maximum opacity score
Score Observation
0 No opacity
0.5 Very faint opacity
1 Scattered or diffuse areas; details of the iris are clearly visible
2 Easily discernible translucent area; details of the iris are slightly obscured
3 Severe corneal opacity; no specific details of the iris are visible; size of the pupil is barely discernible
4 Complete corneal opacity; iris invisible
- Mean fluorescein retention score at 30 minutes post-treatment
Score Observation
0 No fluorescein retention
0.5 Very minor single cell staining
1 Single cell staining scattered throughout the treated area of the cornea
2 Focal or confluent dense single cell staining
3 Confluent large areas of the cornea retaining fluorescein

DECISION CRITERIA: decision criteria as indicated in the TG was used

Results and discussion

In vitro

Results

Results 1

Irritation parameter:

percent corneal swelling

Remarks:

up to 75 min

Value:

2

Negative controls validity:

valid

Positive controls validity:

valid

Remarks on result:

other: ICE class I

Results 2

Irritation parameter:

percent corneal swelling

Remarks:

up to 240 min

Value:

2

Negative controls validity:

valid

Positive controls validity:

valid

Remarks on result:

other: ICE class I

Results 3

Irritation parameter:

cornea opacity score

Value:

0.2

Negative controls validity:

valid

Positive controls validity:

valid

Remarks on result:

other: ICE class I

Results 4

Irritation parameter:

fluorescein retention score

Value:

0.8

Negative controls validity:

valid

Positive controls validity:

valid

Remarks on result:

other: ICE class II

Other effects / acceptance of results:

Overall ICE Class: 2x I, 1x II

Any other information on results incl. tables

Positive Control: Benzalkonium chloride solution (5%)

Observation	Value	ICE class
Mean maximum corneal swelling at up to 75 min	25%	III
Mean maximum corneal swelling at up to 240 min	42%	IV
Mean maximum corneal opacity	4.0	IV
Mean fluorescein retention	3.0	IV
Other Observations	Corneal opacity score 4 was observed in three eyes at 75 minutes after the post-treatment rinse. Loosening of the epithelium was noted in two eyes out of three eyes at 30 and 75 minutes after the post-treatment rinse.
Overall ICE Class	3xIV

 

Negative Control: NaCl (9 g/L saline)

Observation	Value	ICE class
Mean maximum corneal swelling at up to 75 min	0%	I
Mean maximum corneal swelling at up to 240 min	2%0	I
Mean maximum corneal opacity	0.0	I
Mean fluorescein retention	0.0	I
Other Observations	None
Overall ICE Class	3xI

Applicant's summary and conclusion

Interpretation of results:

GHS criteria not met

Conclusions:

In this ICET, the overall ICE classes of the test item were twice I and once II. According to the guideline OECD 438, BuMP is categorized as “No Category”.

Executive summary:

The purpose of this Isolated Chicken Eye Test (ICET) was to evaluate the potential ocular corrosivity and irritancy of the test item BuMP by its ability to induce toxicity in enucleated chicken eyes. The test item was applied in a single dose (30 μL/eye) onto the cornea of isolated chicken eyes in order to potentially classify the test compound as either 1: causing "serious eye damage" (category 1 of the Globally Harmonised System for the Classification and Labelling of Chemicals (GHS)), or 2: not requiring classification for eye irritation or serious eye damage according to the GHS. 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 item exposure) were determined at each of the above time points.
The test item, the positive control [Benzalkonium chloride solution (5 %)], and the negative control (NaCl, 9 g/L saline) were applied in a volume of 30 μL/eye, in such a way to evenly cover the whole cornea surface of each tested eye. Three test item treated eyes, three positive control eyes and one negative control eye were used in this study.
After an exposure period of 10 seconds from the end of the application the cornea surface was rinsed thoroughly with ~20 mL saline solution at ambient temperature and this procedure was repeated for each eye.
In this ICET, the overall ICE classes of the test item were twice I (based on the corneal swelling of 2 % within 240 minutes, based on the corneal opacity score of 0.2) and once II (based on the fluorescein retention of 0.8).
The positive control was classed as corrosive/severely irritating, UN GHS Classification: Category 1 and the negative control had no significant effects on the chicken eye in this study. So, the positive and negative controls showed the expected results. The experiment was considered to be valid.
In this ICET, the overall ICE classes of the test item were twice I and once II. According to the guideline OECD 438, the test item is categorized as “No Category”.