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Toxicological information

Skin irritation / corrosion

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Administrative data

Endpoint:
skin irritation: in vitro / ex vivo
Type of information:
experimental study
Adequacy of study:
key study
Study period:
27 March 2017 to 07 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

Constituent 1
Chemical structure
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: 5 µL distilled water (aqua dest.) was applied to the epidermal surface in order to improve further contact between the powder and the epidermis. The water was gently spread on the surface. Afterwards, approximately 10 ± 2 mg (26.3 mg/cm²) of the powder was applied to the epidermis surface.

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 EPISKIN-SM™ reconstructed human epidermis model (SkinEthic) 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 skin, i.e. the epidermis.
Vehicle:
unchanged (no vehicle)
Details on test system:
RECONSTRUCTED HUMAN EPIDERMIS (RHE) TISSUE
- Model used: EPISKIN-SM™
- Tissue batch number(s): 17-EKIN-014
- 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: at room temperature for 15 +/- 0.5 min
- Temperature of post-treatment incubation (if applicable): 37 +/- 1 °C, 5.0% CO2 for 42 +/- 1 h.

REMOVAL OF TEST MATERIAL AND CONTROLS
-Volume and number of washing steps: The tissues were washed with DPBS to remove any residual test item. Excess DPBS was removed by blotting bottom with blotting paper.
- Observable damage in the tissue due to washing: None reported
- Modifications to validated SOP: None reported

MTT DYE USED TO MEASURE TISSUE VIABILITY AFTER TREATMENT / EXPOSURE
- MTT concentration: 3 mg/mL MTT
- Incubation time: 3 hours
- Spectrophotometer: yes
- Wavelength: at 570 nm
- Filter: filter band
- Filter bandwidth: filter band pass of maximum ± 30 nm in a plate spectrophotometer
- Linear OD range of spectrophotometer: yes

FUNCTIONAL MODEL CONDITIONS WITH REFERENCE TO HISTORICAL DATA
- Viability: not specified
- Barrier function: IC50 determination (SDS concentration, MTT test, n = 14): Specification ≥ 1.5 mg/mL; Result: 2.2 mg/mL
- Morphology: Specification ≥ 19.5; Result: 22.3 ± 1.0, CV = 4.7%; Well-differentiated epidermis consisting of a basal layer, several spinous and granular layers and a thick stratum corneum.
- Contamination: No contamination was reported.
- 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 : triplicate
- Method of calculation used: NSMTT (non-specific MMT) was calculated relative to the negative control of living tissues (NK) per treatment period according to the following formula:
NSMTT [%] = [(ODKT - ODKU)/ODNK] * 100
If non-specific MTT reduction was ≤ 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:

PREDICTION MODEL / DECISION CRITERIA (choose relevant statement)
- The test substance is considered to be irritant to skin if the viability after 15 minutes exposure is less than 50%.
- The test substance is considered to be non-corrosive to skin if the viability after 15 minutes 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 negative control
yes, concurrent positive control
Amount/concentration applied:
TEST MATERIAL
- Amount(s) applied (volume or weight with unit): 10 ± 2 mg + 5 µL aqua dest

NEGATIVE CONTROL
- Concentration (if solution): 10 µL DPBS

POSITIVE CONTROL
- Concentration (if solution): 10 µL 5% SDS solution
Duration of treatment / exposure:
15 minutes
Duration of post-treatment incubation (if applicable):
42 hours
Number of replicates:
Triplicate

Results and discussion

In vitro

Results
Irritation / corrosion parameter:
% tissue viability
Run / experiment:
Experiment I
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 reported
- Direct-MTT reduction: The test item showed no non-specific MTT reducing potential, therefore no additional controls for correction of results were necessary.
- Colour interference with MTT: The test item showed no colouring potential, therefore no additional controls for correction of results were necessary.

DEMONSTRATION OF TECHNICAL PROFICIENCY:
- Mean OD570 nm Blank: value 0.044; cut off < 0.1;
- Mean Absolute OD570 nm NK: 0.610, cut off 0.6 ≤ NK ≤1.5;
- Mean Relative Viability [%] PC: 9.8; cut off ≤ 40%;
- Max. SD of % Viability [%]: 8.1, 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 EpiSkinTM tissue, the reported mean relative tissue viability (% negative control) was > 50 % (104.9 %) after 15 minutes treatment and 42 hours post-incubation.