3,3,6,6-tetramethoxy-2,7-dioxa-3,6-disilaoctane

Eye irritation

Administrative data

Endpoint:

eye irritation: in vitro / ex vivo

Type of information:

experimental study

Adequacy of study:

key study

Study period:

2018-10-09 until 2019-10-11

Reliability:

1 (reliable without restriction)

Rationale for reliability incl. deficiencies:

guideline study

Data source

Reference

Reference Type:

study report

Title:

Unnamed

Year:

2018

Report date:

2018

Materials and methods

Test guideline

Qualifier:

according to guideline

Guideline:

OECD Guideline 492 (Reconstructed Human Cornea-like Epithelium (RhCE) Test Method for Identifying Chemicals Not Requiring Classification and Labelling for Eye Irritation or Serious Eye Damage)

Version / remarks:

25 June 2018

GLP compliance:

yes (incl. QA statement)

Remarks:

THE DEPARTMENT OF HEALTH OF THE GOVERNMENT OF THE UNITED KINGDOM

Test material

Test material information

Constituent 1

Reference substance name:

3,3,6,6-tetramethoxy-2,7-dioxa-3,6-disilaoctane

EC Number:

242-285-6

EC Name:

3,3,6,6-tetramethoxy-2,7-dioxa-3,6-disilaoctane

Cas Number:

18406-41-2

Molecular formula:

C8H22O6Si2

IUPAC Name:

3,3,6,6-tetramethoxy-2,7-dioxa-3,6-disilaoctane

Test material form:

liquid

Specific details on test material used for the study:

SOURCE OF TEST MATERIAL
- Batch No.of test material: 611220160318
- Storage stability: 31 December 2018

STABILITY AND STORAGE CONDITIONS OF TEST MATERIAL
- Storage condition of test material: refrigerator
- Stability under test conditions: guaranteed by the sponsor under storage conditions
- Solubility and stability of the test substance in the solvent/vehicle: The test item was used as supplied by the sponsor.

TREATMENT OF TEST MATERIAL PRIOR TO TESTING
- no prior treatment

Test animals / tissue source

Species:

human

Strain:

other: normal human derived epidermal keratinocytes

Details on test animals or tissues and environmental conditions:

Description of the cell system used: Reconstructed human cornea-like epithelium
- Model used: EpiOcular model (OCL-200)
- Supplier: MatTek In Vitro Life Science Laboratories, Bratislava, Slovakia
- Tissue lot number: 27073
- Assay medium lot number: 100818ISA
- no further details given

Test system

Vehicle:

unchanged (no vehicle)

Controls:

yes

yes, concurrent positive control

yes, concurrent negative control

Amount / concentration applied:

TEST MATERIAL
- Amount applied: 50 µL
- Concentration: undiluted test item was used

BENCHMARK CONTROL, NEGATIVE CONTROL, POSITIVE CONTROL
- Amount applied: 50 µL
- Concentration: all controls were applied as supplied by the sponsor

Duration of treatment / exposure:

30 minutes

Duration of post- treatment incubation (in vitro):

2 hours

Number of animals or in vitro replicates:

tested in duplicates

Details on study design:

TEMPERATURE USED FOR TEST SYSTEM
- Temperature used during treatment / exposure: 37°C
- Temperature of post-treatment incubation: 37°C

REMOVAL OF TEST MATERIAL AND CONTROLS
- Volume and number of washing steps: The tissues were immersed and swirled three times in each of three beakers filled with sterile PBS.

MTT DYE USED TO MEASURE TISSUE VIABILITY AFTER TREATMENT / EXPOSURE
- MTT concentration: 1.0 mg / mL MTT diluent
- Incubation: 3 hours, 37°C, 5% CO2, incubated in the dark
- Spectrophotometer: Labtech LT-4500 microplate reader
- Wavelength: 570 nm, without reference filter

NUMBER OF INDEPENDENT TEST SEQUENCES / EXPERIMENTS TO DERIVE FINAL PREDICTION: 1

PREDICTION MODEL / DECISION CRITERIA
- The test substance can not be predicted based on EU CLP/UN GHS Category 1 and Category 2 if the mean relative tissue viability with a test material is less than 60%.
- The test substance is considered to be non- irritant to the eye if the mean relative tissue viability with a test material is greater than 60%.
- Justification for the selection of the cut-off point is based on OECD TG 492.

ACCEPTANCE CRITERIA
- Negative control: Tissue viability is acceptable if the mean OD570 of the negative control (NC) is ≥ 0.8. The mean OD570 of the NC should not exceed 2.5.
- Positive control: Methyl acetate used as positive control (PC) usually leads to a tissue viability of approx. 25%. A viability of ≤ 50% is acceptable.
- Variability: Two tissues were treated under the same conditions. A variability between the tissues is considered to be acceptable if the difference of the viability is ≤ 20%.
- Benchmark control: The assay establishes the acceptance criteria for an acceptable test if the relative mean tissue viability for the benchmark control treated tissues was ≤60% historicrelative to the negative control treated tissues

HISTORICAL DATA : As dicussed before was the benchmark control used to prove the proviciency. No historical data exist to date.

Results and discussion

In vitro

Results

Irritation parameter:

other: relative mean viability

Run / experiment:

one run / mean of 2 individual experiments

Value:

87.8

Vehicle controls validity:

not applicable

Negative controls validity:

valid

Remarks:

OD570 = 2.787, greater than the upper limit of 2.5 set out in the acceptance criteria; Further description is given below (other effects).

Positive controls validity:

valid

Remarks on result:

no indication of irritation

Other effects / acceptance of results:

The results of the test are given in table 1.

DEMONSTRATION OF TECHNICAL PROFICIENCY:
Diethyl toluamide was used as a benchmark control as demonstration of proficiency had not been completed in the laboratory.
Based on an agreement, the benchmark control was tested alongside with the test item and negative and positive controls. Diethyl toluamide was selected based on the OECD 492 due to its expected eye irritancy potential of EU CLP/UN GHS Category 2B.

ACCEPTANCE OF RESULTS:
- Acceptance criteria met for negative control:
At 2.787 the mean optical density (OD570) of the negative control tissues was greater than the upper limit of 2.5 set out in the acceptance criteria.
However, as the results of the controls and test item gave unequivocal conclusions it was considered unnecessary to repeat the test.
Besides, test item tissues were both indicative of a negative response and were not close to the cut-off for irritation.
Therefore, the result of the negative control was considered to have not impacted upon the conclusion of the study and the integrity or validity of the study was not compromised.

- Acceptance criteria met for positive control:
The relative mean tissue viability for the positive control treated tissues was 34.7% relative to the negative control treated tissues. The positive control acceptance criterion was therefore satisfied.

- Acceptance criteria met for benchmark control:
The relative mean tissue viability for the benchmark control treated tissues was 31.4% relative to the negative control treated tissues. The benchmark control acceptance criterion was therefore satisfied.

Any other information on results incl. tables

Table 1: Mean OD570 values and percentage viabilities for the negative control item, positive control item, benchmark control item and test item

Item	OD570 of tissues	Mean OD570 of duplicate tissues	Relative individual tissue viability (%)	Relative mean viability (%)	CV of Relative mean viability (%)
Negative Control Item	2.873	2.787	103.1	100*	4.4
	2.701		96.9
Positive Control Item	1.073	0.968	38.5	34.7	15.3
	0.863		31.0
Test Item	2.521	2.448	90.5	87.8	4.2
	2.375		85.2
Benchmark Control	0.864	0.876	31.0	31.4	1.9
	0.888		31.9

Applicant's summary and conclusion

Interpretation of results:

GHS criteria not met

Conclusions:

According to the conditions of the test, the test item was classified as non-irritant.