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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:
25 Apr 2017 to 01 may 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 guidelineopen allclose all
Qualifier:
according to
Guideline:
OECD Guideline 439 (In Vitro Skin Irritation: Reconstructed Human Epidermis Test Method)
Version / remarks:
28 July 2015
Qualifier:
according to
Guideline:
EU Method B.46 (In Vitro Skin Irritation: Reconstructed Human Epidermis Model Test)
Version / remarks:
20 July 2012
GLP compliance:
yes

Test material

Reference
Name:
Unnamed
Type:
Constituent
Test material form:
liquid
Specific details on test material used for the study:
SOURCE OF TEST MATERIAL
- Identification: 0125 SCHWEFELSÄURE, MIPA-SALZ
- Source of test material: Zschimmer and Schwarz GmbH + Co. KG.
- Batch: CH 220612
- Purity/Composition: UVCB

STABILITY AND STORAGE CONDITIONS OF TEST MATERIAL
- Test item storage: At room temperature
- Stable under storage conditions until: 07 December 2017 (expiry date)

OTHER SPECIFICS:
- Appearance: Yellow turbid liquid

In vitro test system

Test system:
human skin model
Source species:
human
Cell type:
non-transformed keratinocytes
Cell source:
other: cultured
Justification for test system used:
In the interest of sound science and animal welfare, a sequential testing strategy is recommended to minimize the need of in vivo testing. One of the validated in vitro skin irritation tests is the EPISKIN test, which is recommended in international guidelines (e.g. OECD and EC).
Vehicle:
unchanged (no vehicle)
Details on test system:
RECONSTRUCTED HUMAN EPIDERMIS (RHE) TISSUE
- Model used: EPISKIN Small ModelTM
- Background: The EPISKIN Small Model is a three-dimensional human epidermis model, which consists of adult human derived epidermal keratinocytes which have been seeded on a dermal substitute consisting of a collagen type I matrix coated with type IV collagen. The keratinocytes were cultured for 13 days, which results in a highly differentiated and stratified epidermis model comprising the main basal, supra basal, spinous and granular layers and a functional stratum corneum.
- Tissue batch number: 17-EKIN-017
- Source: SkinEthic Laboratories, Lyon, France.
- Date of initiation of testing: 25 April 2017
- Expiration date: 01 May 2017

TEST FOR THE INTERFERENCE OF THE TEST ITEM WITH THE MTT ENDPOINT
A test item may interfere with the MTT endpoint if it is coloured and/or it is able to directly reduce MTT. The cell viability measurement is affected only if the test item is present on the tissues when the MTT viability test is performed. The test item was checked for possible direct MTT reduction and colour interference in the Skin corrosion test using EpiDerm as a skin model. Because solutions did not turn blue / purple and a blue / purple precipitate was not observed it was concluded that the test item did not interfere with the MTT endpoint.

TEST SYSTEM SET UP
On the day of receipt the tissues were transferred to 12-well plates and pre-incubated with pre-warmed Maintenance Medium for 22 hours at 37°C. Maintenance medium and Assay medium were supplied by Skinethic Laboratories, Lyon, France.

ENVIRONMENTAL CONDITIONS
All incubations, with the exception of the test item incubation of 15 minutes at room temperature, were carried out in a controlled environment, in which optimal conditions were a humid atmosphere of 80 - 100% (actual range 79 - 93 %), containing 5.0 ± 0.5% CO2 in air in the dark at 37.0 ± 1.0°C (actual range 36.6 – 37.4 °C). Temperature and humidity were continuously monitored throughout the experiment. The CO2 percentage was monitored once on each working day. Temporary deviations from the temperature, humidity and CO2 percentage may occur due to opening and closing of the incubator door. Based on laboratory historical data these deviations are considered not to affect the study integrity.

TEST ITEM PREPARATION
- No correction was made for the purity/composition of the test compound.
- The liquid test item was applied undiluted (25 µL) directly on top of the tissue. The test item was spread to match the size of the tissue.

APPLICATION/TREATMENT OF THE TEST ITEM
- The test was performed on a total of 3 tissues per test item together with negative and positive controls. 25 μL of the undiluted test item was added into 12-well plates on top of the skin tissues.
- Three tissues were treated with 25 μL PBS (negative control) and 3 tissues with 25 μL 5% SDS (positive control) respectively. The positive control was re-spread after 7 minutes contact time.
- After the exposure period of 15 ± 0.5 minutes at room temperature, the tissues were washed with phosphate buffered saline to remove residual test item. After rinsing, the cell culture inserts were each dried carefully and moved to a new well on 2 mL pre-warmed maintenance medium until all tissues were dosed and rinsed.
- Subsequently the skin tissues were incubated for 42 hours at 37°C.

CELL VIABILITY MEASUREMENT
After incubation, cell culture inserts were dried carefully to remove excess medium and were transferred into a 12-wells plate prefilled with 2 mL MTT-solution (0.3 mg/mL in PBS). The tissues were incubated for 3 h at 37°C. After incubation the tissues were placed on blotting paper to dry the tissues. Total biopsy was made by using a biopsy punch. Epidermis was separated from the collagen matrix and both parts were placed in pre-labelled microtubes and extracted with 500 μL isopropanol (Merck, Darmstadt, Germany). Tubes were stored refrigerated and protected from light for 69 hours. The amount of extracted formazan was determined spectrophotometrically at 570 nm in duplicate with the TECAN Infinite® M200 Pro Plate Reader.

ACCEPTABILITY CRITERIA
The in vitro skin irritation test is considered acceptable if it meets the following criteria:
- The absolute mean OD570 (optical density at 570 nm) of the three tissues of the negative control should reasonably be within the laboratory historical control data range and the Standard Deviation value (SD) of the % viability should be ≤18.
- The mean relative tissue viability of the positive control should be ≤50% relative to the negative control and the Standard Deviation value (SD) of the % viability should be ≤18.
- The SD calculated from individual % tissue viabilities of the three identically treated replicates should be ≤18.

INTERPRETATION
A test item is considered irritant in the skin irritation test if:
- The relative mean tissue viability of three individual tissues after 15 minutes of exposure to the test item and 42 hours of post incubation is ≤ 50% of the mean viability of the negative controls.
A test item is considered non-irritant in the in vitro skin irritation test if:
- The relative mean tissue viability of three individual tissues after 15 minutes of exposure to the test item and 42 hours of post incubation is > 50% of the mean viability of the negative controls.
Control samples:
yes, concurrent negative control
yes, concurrent positive control
Amount/concentration applied:
CONTROLS
- Negative control: 25 μL PBS
- Positive control: 25 μL SDS

TEST ITEM
The liquid test item was applied undiluted (25 μL) directly on top of the tissue
Duration of treatment / exposure:
15 minutes
Duration of post-treatment incubation (if applicable):
42 hours
Number of replicates:
3

Results and discussion

In vitro

Results
Irritation / corrosion parameter:
% tissue viability
Run / experiment:
Irritation test: 15 minute exposure
Value:
83
Vehicle controls validity:
not applicable
Negative controls validity:
valid
Positive controls validity:
valid
Remarks on result:
no indication of irritation
Other effects / acceptance of results:
ACCEPTANCE OF RESULTS:
- The test item did not interact with the MTT endpoint.
- Acceptance criteria for negative control are met.
- Acceptance criteria for positive control are met.
- Acceptance criteria for variability between replicate measurements are met.

Applicant's summary and conclusion

Interpretation of results:
GHS criteria not met