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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 Sep - 04 Nov 2016
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 guidelineopen allclose all
Qualifier:
according to
Guideline:
OECD Guideline 439 (In Vitro Skin Irritation: Reconstructed Human Epidermis Test Method)
Version / remarks:
adopted 28 July 2015
Deviations:
no
Qualifier:
according to
Guideline:
EU Method B.46 (In Vitro Skin Irritation: Reconstructed Human Epidermis Model Test)
Version / remarks:
Commission Regulation (EC) No 440/2008, 1st
ATP of 23 July 2009
Deviations:
no
GLP compliance:
yes (incl. certificate)
Remarks:
Hess. Ministerium für Umwelt, Klimaschutz, Landwirtschaft und Verbraucherschutz, Wiesbaden, Germany

Test material

Reference
Name:
Unnamed
Type:
Constituent

In vitro test system

Test system:
human skin model
Source species:
human
Cell type:
non-transformed keratinocytes
Cell source:
other: EpiDerm™
Source strain:
not specified
Vehicle:
unchanged (no vehicle)
Details on test system:
RECONSTRUCTED HUMAN EPIDERMIS (RHE) TISSUE
- Model used: EpiDerm™ (MatTek Corporation, Bratislava, Slovakia)
- Tissue batch number: 23372
- Delivery date: 01 Nov 2016
- Date of initiation of testing: 01 Nov 2016

TEMPERATURE USED FOR TEST SYSTEM
- Temperature used during treatment / exposure: 37 ± 1.5 °C for 35 min in the incubator; thereafter at room temperature for 25 min in a sterile bench
- Temperature of post-treatment incubation: 37 ± 1.5 °C for 42 h

REMOVAL OF TEST MATERIAL AND CONTROLS
-Volume and number of washing steps: Tissues were gently rinsed with DPBS at least 15 times in order to remove any residual test material. After the rinsing the inserts were submerged in DPBS at least three times. Afterwards the inserts were once again rinsed with sterile DPBS from the inside and the outside.

MTT DYE USED TO MEASURE TISSUE VIABILITY AFTER TREATMENT / EXPOSURE
- MTT concentration: 1 mg/mL
- Incubation time: 3 h
- Spectrophotometer: microplate reader (Versamax® Molecular Devices, Softmax Pro, version 4.7.1)
- Wavelength: 570 nm

FUNCTIONAL MODEL CONDITIONS WITH REFERENCE TO HISTORICAL DATA
- Viability: The quality of the EpiDerm™ tissue was assessed by undertaking an MTT cell viability test. The determined OD (540 - 570 nm) was 1.587 ± 0.089 (acceptance criteria: 1.0 - 3.0).
- Barrier function: The barrier function was assessed by determination of the exposure time required to reduce tissue viability by 50% (ET-50) upon application of 100 µL of 1% Triton X-100. The ET-50 value was determined to be 6.25 h (acceptance criteria: 4.77-8.72 h).
- Contamination: The cells used to produce the EpiDerm™ tissue were screened for the presence of viruses, bacteria, yeast and other fungi.

NUMBER OF REPLICATE TISSUES: 3

CONTROL TISSUES USED IN CASE OF MTT DIRECT INTERFERENCE: Since the test substance did not directly reduce MTT, an additional test with freeze-killed tissues was not performed.

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

PREDICTION MODEL / DECISION CRITERIA
- The test substance is considered to be irritant to skin if the viability after 1 hour exposure is less than 50%.
Control samples:
yes, concurrent negative control
yes, concurrent positive control
Amount/concentration applied:
TEST MATERIAL
- Amount applied: 30 µL

NEGATIVE CONTROL
- Amount applied: 30 µL

POSITIVE CONTROL
- Amount applied: 30 µL
-Concentration: 5%
Duration of treatment / exposure:
60 min
Duration of post-treatment incubation (if applicable):
approx. 42 h
Number of replicates:
triplicates for each treatment and control group

Results and discussion

In vitro

Results
Irritation / corrosion parameter:
% tissue viability
Remarks:
mean value of 3 tissues
Run / experiment:
60 min exposure
Value:
2.5
Vehicle controls validity:
not applicable
Negative controls validity:
valid
Positive controls validity:
valid
Other effects / acceptance of results:
OTHER EFFECTS:
- Direct-MTT reduction: The test substance was not considered to be a MTT reducer.
- Colour interference with MTT: The test substance did not change colour when mixed with deionised water. Also its intrinsic colour was not intensive.

ACCEPTANCE OF RESULTS:
- Acceptance criteria met for negative control: The negative control OD (1.978, 2.115, 1.902) was in the range of the required acceptability criterion of mean OD ≥ 0.8 and ≤ 2.8 for the 60 min treatment interval thus showing the quality of the tissues.
- Acceptance criteria met for positive control: Exposure to the positive control induced a decrease in the relative absorbance as compared to the negative control to 3.1% thus confirming the validity of the test system.
- Acceptance criteria met for variability between replicate measurements: The relative standard deviations of the 3 identical replicates of the test substance and negative control in the main test were below 10% (threshold of OECD 439: <18%).

Any other information on results incl. tables

Table 2. Results after treatment with the test substance and controls

 

 

Absorbance at 570 nm *

 

 

Mean absorbance

of 3 wells blank corrected

Rel. absorbance (%) **

Rel. SD (%)

Rel. absorbance (% of negative control)***

Tissue 1

Tissue 2

Tissue 3

Tissue 1

Tissue 2

Tissue 3

Negative control

1.978

2.115

1.902

1.998

99.0

105.8

95.2

5.4

100.0

Positive control

0.064

0.062

0.057

0.061

3.2

3.1

2.9

5.8

3.1

Test substance

0.051

0.054

0.044

0.050

2.5

2.7

2.2

10.0

2.5

* Mean of 3 replicate wells after blank correction (mean blank value: 0.038)

** Relative absorbance per tissue (rounded values): 100 × (absorbance tissue) / (mean absorbance negative control)

*** Relative absorbance per treatment group (rounded values): 100 × (mean absorbance test item/positive control) / (mean absorbance negative control)

Applicant's summary and conclusion

Interpretation of results:
other: irritating potential (Skin Irrit. 2 or Skin Corr. 1 according to Regulation (EC) No 1272/2008)
Conclusions:
Under the conditions of the conducted test, the test substance possessed irritating properties towards reconstructed human epidermis tissue in the EpiDerm™ model.
Executive summary:

The skin irritation potential of the test substance was assesed by an in vitro skin irritation test using a reconstructed human skin model according to OECD Guideline 439 and in compliance with GLP (2017). After treatment with the test substance for 60 min the tissue viability decreased to 2.5% compared to the negative control (threshold for irritancy ≤ 50%). Therefore, the test substance is considered to possess an irritant potential towards human-derived epidermal keratinocytes.