2,4-dithiapentane

Eye irritation

Administrative data

Endpoint:

eye irritation: in vitro / ex vivo

Type of information:

experimental study

Adequacy of study:

weight of evidence

Study period:

17 May 2017 - 06 July 2017

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 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)

Version / remarks:

2013

Deviations:

no

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)

Version / remarks:

2017

Deviations:

no

GLP compliance:

yes (incl. QA statement)

Test material

Test material information

Constituent 1

Reference substance name:

2,4-dithiapentane

EC Number:

216-577-9

EC Name:

2,4-dithiapentane

Cas Number:

1618-26-4

Molecular formula:

C3H8S2

IUPAC Name:

bis(methylsulfanyl)methane

Test material form:

liquid

Test animals / tissue source

Species:

cattle

Details on test animals or tissues and environmental conditions:

SOURCE OF COLLECTED EYES
- Source: Odenwaldschlachthof Brensbach, 64395 Brensbach, Germany
- Age at study initiation: 16 -28 months
- Corneal diameter: 26 - 27 mm
- Storage, temperature and transport conditions of ocular tissue: cooled on ice
- Time interval prior to initiating testing: The corneas were prepared immediately after delivery of the eyes to the laboratory.
- Indication of any existing defects or lesions in ocular tissue samples: Eyes presenting defects such as vascularization, pigmentation, opacity and scratches were discarded.

Test system

Vehicle:

unchanged (no vehicle)

Controls:

yes, concurrent positive control

yes, concurrent negative control

Amount / concentration applied:

TEST MATERIAL
- Volume applied: 750 µL
- Concentration: 20%

VEHICLE
- Volume applied: 750 µL

Duration of treatment / exposure:

10 minutes

Duration of post- treatment incubation (in vitro):

120 minutes

Number of animals or in vitro replicates:

Three corneas were used per group (negative control, positive control and test item group).

Details on study design:

SELECTION AND PREPARATION OF CORNEAS
All eyes were carefully examined macroscopically for defects. A rim of about 2 to 3 mm of tissue (sclera) was left for stability and handling of the isolated cornea.

QUALITY CHECK OF THE ISOLATED CORNEAS
Corneas presenting defects such as vascularization, pigmentation, opacity or scratches were discarded.

NUMBER OF REPLICATES: 3

NEGATIVE CONTROL USED: 0.9% sodium chloride solution

POSITIVE CONTROL USED: N,N-dimethylformamide

APPLICATION DOSE AND EXPOSURE TIME: 750 µL of a 20% solution were applied for 10 minutes

TREATMENT METHOD: closed chamber

POST-INCUBATION PERIOD: yes, 120 minutes

REMOVAL OF TEST SUBSTANCE
- Number of washing steps after exposure period:at least 3 times with washing medium

- POST-EXPOSURE INCUBATION: in fresh medium

METHODS FOR MEASURED ENDPOINTS:
- Corneal opacity: baseline opacity was determined with a calibrated opacitometer, the light transmission through the corneas, given as lux value, was recorded in a table and thereafter converted into an opacity value (baseline opacity values).
- Corneal permeability: corneas were incubated again in an incubator in a horizontal position at 32 ± 1°C for 90 minutes, amount of fluorescein that crossed the cornea was measured spectrophotometrically 490 nm

SCORING SYSTEM: In Vitro Irritancy Score (IVIS)
The following formula (referring to OECD Guideline 437) was used to determine the In Vitro Irritancy Score (IVIS) of the negative control:
IVIS = mean opacity value + (15 x mean permeability OD490 value)
The following formula was used to determine the In Vitro Irritancy Score (IVIS) of the positive control and the test item:
IVIS = corrected opacity value + (15 x corrected permeability OD490 value)
- The In Vitro Irritancy Score (IVIS) was calculated for each individual treatment and positive control cornea. The mean In Vitro Irritancy Score (IVIS) value of each treated group was calculated from the individual In Vitro Irritancy Score (IVIS) values.

DECISION CRITERIA:
IVIS ≤ 3 No Category (according to GHS)
IVIS > 3; ≤ 55 No prediction can be made
IVIS > 55 Serious eye damage, Category 1 (according to GHS)

ACCEPTANCE CRITERIA:
A test is considered acceptable if the positive control gives an IVIS that falls within two standard deviations of the current historical mean(IVIS positive control: 75.3 - 120.2).
The negative control responses should result in an IVIS that falls within three standard deviations of the current historical mean (IVIS negative control: -1.2 - 5.3).
A single test run with three corneas should be sufficient for a test item when the resulting classification is unequivocal. In cases of the following borderline results in the first testing run, a second test run should be considered.
- 2 of the 3 corneas give discordant predictions from the mean of all 3 corneas or
- 1 of the 3 corneas give discordant predictions from the mean of all 3 corneas, and the discordant result is >10 IVIS units from the cut-off threshold of 55.

Results and discussion

In vitro

Results

Results 1

Irritation parameter:

in vitro irritation score

Remarks:

replicate 1

Run / experiment:

1

Value:

21.37

Negative controls validity:

valid

Positive controls validity:

valid

Results 2

Irritation parameter:

in vitro irritation score

Remarks:

replicate 2

Run / experiment:

1

Value:

20.265

Negative controls validity:

valid

Positive controls validity:

valid

Results 3

Irritation parameter:

in vitro irritation score

Remarks:

replicate 3

Run / experiment:

1

Value:

26.5

Negative controls validity:

valid

Positive controls validity:

valid

Other effects / acceptance of results:

OTHER EFFECTS:
- Visible damage on test system: no
No observations (e.g.tissue peeling, residual test chemical, non-uniform opacity patterns) were seen in a visually inspection of the corneas after treatment.

ACCEPTANCE OF RESULTS:
- Acceptance criteria met for negative control: yes
- Acceptance criteria met for positive control: yes
The resulting classification of the test item in this study is unequivocal and no borderline results were obtained. Therefore, a single testing run composed of three corneas per group was considered sufficient.

Any other information on results incl. tables

Table 1 Opacity, permeability and IVIS results

		Opacity	Permeability	IVIS
				per cornea	per group (mean value)	Standard deviation
Negative control	0.9%sodium chloride solution	0.5	-0.001	0.485	1.7	1.5
		1.1	0.003	1.145
		3.4	-0.002	3.370
Positive control	N,N-dimethyl- formamide	102.4	0.627	111.805	103.3	9.1
		83.8	0.665	93.775
		91.2	0.875	104.325
Testitem	Test item	11.2	0.678	21.370	22.7	3.3
		11.1	0.611	20.265
		8.8	1.180	26.500

Applicant's summary and conclusion

Interpretation of results:

other: not Category 1 (irreversible effects on the eye) based on GHS

Conclusions:

Based on the results of the present 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 (no Category).

Executive summary:

The objective of the present study was to examine the potential of the test item to induce serious eye damage in the BCOP assay. The BCOP assay with isolated fresh bovine corneas is an acceptedin vitromodel for ocular hazard assessment.

To determine the eye hazard potential the induced opacity and increased permeability was investigated in isolated bovine corneas after exposure to the test item. As negative control 0.9% sodium chloride solution and as positive control N,N-dimethylformamide was used.

Three corneas were used per group (negative control, positive control or test item group).

After a first opacity measurement of the untreated bovine corneas, 750 µLof the test item, positive or negative control were applied on the corneas and incubated for 10 minutes. After the incubation phase the test item, the positive, and the negative control were rinsed from the corneas and the opacity was measured again.

After the opacity measurements, the permeability of the corneas was determined by application of a fluorescein solution for 90 minutes. The amount of fluorescein solution that crossed the cornea was measured spectrophotometrically.

The opacity and permeability assessments were combined to determine an In Vitro Irritancy Score (IVIS).

After treatment with the negative control (0.9% sodium chloride solution) the calculated IVIS was1.7 (study acceptance criteria range:-1.2 - 5.3). Treatment with the positive control (N,N-dimethylformamide) revealed an IVIS of 103.3 (study acceptance criteria range:75.3 - 120.2). Therefore, the study fulfilled the acceptance criteria.

The IVIS obtained after treatment with the test item was 22.7 and, thus higher than 3 and lower than 55, 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 (no Category).