Octaphenylcyclotetrasiloxane

Skin irritation / corrosion

Administrative data

Endpoint:

skin irritation: in vitro / ex vivo

Type of information:

experimental study

Adequacy of study:

key study

Study period:

2 March 2017 to 24 April 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

Qualifier:

according to guideline

Guideline:

OECD Guideline 439 (In Vitro Skin Irritation: Reconstructed Human Epidermis Test Method)

Version / remarks:

2015

Deviations:

no

GLP compliance:

yes (incl. QA statement)

Test material

Test material information

Constituent 1

Reference substance name:

Octaphenylcyclotetrasiloxane

EC Number:

208-904-9

EC Name:

Octaphenylcyclotetrasiloxane

Cas Number:

546-56-5

Molecular formula:

C48H40O4Si4

IUPAC Name:

octaphenyl-1,3,5,7,2,4,6,8-tetraoxatetrasilocane

Test material form:

solid

Details on test material:

- Density: 1.185 g/cm3

Specific details on test material used for the study:

STABILITY AND STORAGE CONDITIONS OF TEST MATERIAL
- Storage condition of test material: at room temperature
- Stability under test conditions: stable
- Solubility and stability of the test substance in the solvent/vehicle:

TREATMENT OF TEST MATERIAL PRIOR TO TESTING
- Treatment of test material prior to testing: 25 µL of sterile DPBS was applied to the epidermal surface in order to improve the contact between the powder and the epidermis. Afterwards, 25 mg (39 mg/cm2) of the test item was applied directly atop the EpiDermTM tissue using an application spoon avoiding compression of the test item. The test item was spread to match size of the tissue by gently shaking the inserts or by using a bulb-headed Pasteur pipette.
- Preliminary purification step (if any): not specified

In vitro test system

Test system:

human skin model

Source species:

human

Cell type:

non-transformed keratinocytes

Cell source:

other: not specified

Source strain:

not specified

Details on animal used as source of test system:

Not applicable

Justification for test system used:

This test uses the EpiDerm™ reconstructed human epidermis model (MatTek) which consists of normal human epidermal keratinocytes (NHEK) and therefore represents in vitro the target organ of the species of interest and closely mimics the biochemical and physiological properties of the upper parts of the human, i.e. the epidermis.

Vehicle:

unchanged (no vehicle)

Details on test system:

RECONSTRUCTED HUMAN EPIDERMIS (RHE) TISSUE
- Model used: EpiDerm™
- Tissue batch number(s): 25086
- Production date: not specified
- Shipping date: not specified
- Delivery date: not specified
- Date of initiation of testing: not specified

TEMPERATURE USED FOR TEST SYSTEM
- Temperature used during treatment / exposure: 37 +/- 1 °C, 5.0% CO2
- Temperature of post-treatment incubation (if applicable): 37 +/- 1 °C, 5.0% CO2

REMOVAL OF TEST MATERIAL AND CONTROLS
-Volume and number of washing steps: The tissues were washed by filling and emptying the inserts 15 times with DPBS using a constant stream in about 1.5 cm distance from the tissue surface.
- Observable damage in the tissue due to washing: No damage specified.
- Modifications to validated SOP: Not specified

MTT DYE USED TO MEASURE TISSUE VIABILITY AFTER TREATMENT / EXPOSURE
- MTT concentration: 5 mg/mL MTT
- Incubation time: 3 h +/- 5 min at 37 +/- 1 °C, 5.0% CO2, humidified to 95%.
- Spectrophotometer: plate spectrophotometer using isopropanol as a blank.
- Wavelength: 570 nm
- Filter: OD was measured at 570 nm with a filter band pass of maximum ± 30 nm without reference wavelength.
- Filter band width: Not specified
- Linear OD range of spectrophotometer: yes

FUNCTIONAL MODEL CONDITIONS WITH REFERENCE TO HISTORICAL DATA
- Viability: 1.581+/-0.238, acceptance criteria OD (540-570 nm) [1.0-3.0]
- Barrier function: 5.58 h, acceptance criteria ET-50 [4.77-8.72 h]
- Morphology: not specified
- Contamination: No contamination was detected.
- Reproducibility: Not specified.

NUMBER OF REPLICATE TISSUES: Triplicate tissues

CONTROL TISSUES USED IN CASE OF MTT DIRECT INTERFERENCE
- Fresh tissues / killed tissues: killed tissues
- Procedure used to prepare the killed tissues (if applicable): not specified
- N. of replicates : duplicate
- Method of calculation used: NSMTT (non-specific MTT) was then calculated relative to the negative control of living tissues (NK) according to the following formula:
NSMTT [%] = [(ODKT - ODKU)/ODNK] * 100
If the test item is classified as non-irritant and if non-specific MTT reduction is ≤ 30% relative to the negative control of living epidermis, the true MTT metabolic conversion (TODTT) of the test item treated living tissues TM was corrected according to the following formula:
TODTT = ODTM – (ODKT – ODKU)

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

PREDICTION MODEL / DECISION CRITERIA (choose relevant statement)
- The test substance is considered to be corrosive to skin if the mean relative tissue viability after 1 hour exposure is less than 50%.
- The test substance is considered to be non-corrosive to skin if the mean relative tissue viability after 1 hour exposure is greater than or equal to 50%.
- Justification for the selection of the cut-off point(s) if different than recommended in TG 431 and 439: not applicable

Control samples:

yes, concurrent positive control

other: Negative control: Dulbecco’s phosphate buffered saline (DPBS);

Amount/concentration applied:

TEST MATERIAL
- Amount(s) applied (volume or weight with unit): 25 mg + 25 µL DPBS

NEGATIVE CONTROL
- Concentration (if solution): 30 µL DPBS

POSITIVE CONTROL
- Concentration (if solution): 30 µL 5% SDS solution

Duration of treatment / exposure:

60 min

Duration of post-treatment incubation (if applicable):

42 hours

Number of replicates:

Triplicate tissues were used.

Results and discussion

In vitro

Results

Irritation / corrosion parameter:

% tissue viability

Run / experiment:

No 1 expressed in percentage of negative control

Value:

> 50

Vehicle controls validity:

not applicable

Negative controls validity:

valid

Positive controls validity:

valid

Other effects / acceptance of results:

- OTHER EFFECTS:
- Visible damage on test system: none observed
- Direct-MTT reduction: The test item showed no non-specific reduction of MTT. Therefore, no additional controls were necessary.
- Colour interference with MTT: The test item showed no colouring after mixture with aqua dest. and isopropanol.

DEMONSTRATION OF TECHNICAL PROFICIENCY:
- Mean Absolute OD570 nm Negative control (NC): 2.038, cut off 0.8 ≤ NK ≤ 2.8
- Relative Viability [%] Positive control (PC): 3.5, cut off ≤ 20%
- SD Viability [%]: 0.2 – 4.9, cut off ≤ 18%


ACCEPTANCE OF RESULTS:
- Acceptance criteria met for negative control: yes
- Acceptance criteria met for positive control: yes
- Acceptance criteria met for variability between replicate measurements: 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 the in vitro skin irritation study with octaphenylcyclotetrasiloxane (CAS 546-56-5) using EpiDermTM tissue, the reported mean relative tissue viability (% negative control) was > 50 % (91.4 %) after 60 minutes treatment and 42 hours post-incubation.