Registration Dossier

Administrative data

Endpoint:
skin corrosion: in vitro / ex vivo
Type of information:
experimental study
Adequacy of study:
key study
Study period:
From 2015-09-14 to 2015-09-18
Reliability:
1 (reliable without restriction)
Rationale for reliability incl. deficiencies:
guideline study

Data source

Reference
Reference Type:
study report
Title:
Unnamed
Year:
2015
Report Date:
2015

Materials and methods

Test guidelineopen allclose all
Qualifier:
according to
Guideline:
OECD Guideline 431 (In Vitro Skin Corrosion: Human Skin Model Test)
Deviations:
no
Qualifier:
according to
Guideline:
EU Method B.40 (In Vitro Skin Corrosion: Transcutaneous Electrical Resistance Test (TER))
Deviations:
no
GLP compliance:
yes (incl. certificate)

Test material

Reference
Name:
Unnamed
Type:
Constituent
Test material form:
solid: particulate/powder
Details on test material:
- Physical state: powder
- Appearance: white powder
Specific details on test material used for the study:
SOURCE OF TEST MATERIAL
- Source and lot/batch No.of test material: 0020726249
- Expiration date of the lot/batch: 2016-11-13 (retest date)
- Purity test date: no data

STABILITY AND STORAGE CONDITIONS OF TEST MATERIAL
- Storage condition of test material: at room temperature
- Stability under test conditions: no data

TREATMENT OF TEST MATERIAL PRIOR TO TESTING
- Treatment of test material prior to testing: the test item was applied neat directly on top of the skin tissue.

Test animals

Species:
other: model of human-derived epidermal keratinocytes
Strain:
other: not applicable
Details on test animals and environmental conditions:
TEST SYSTEM
- EpiDerm Skin Model (EPI-200, Lot no.: 22673 kit W), supplied by MatTek Corporation, Ashland MA, U.S.A
- The model consists of normal, human-derived epidermal keratinocytes which have been cultured to form a multilayered, highly differentiated model of the human epidermis. It consists of organized basal, spinous and granular layers, and a multi-layered stratum corneum containing intercellular lamellar lipid layers arranged in patterns analogous to those found in vivo. The EpiDerm tissues (surface 0.6 cm²) were cultured on polycarbonate membranes of 10 mm cell culture inserts.

ENVIRONMENTAL CONDITIONS
- All incubations, with the exception of the test item incubation of 3 minutes at room temperature, were carried out in a controlled environment, in which optimal conditions were a humid atmosphere of 80 - 100% (actual range 60 - 86 %), containing 5.0 ± 0.5% CO2 in air in the dark at 37.0 ± 1.0°C (actual range 36.2 - 37.1 °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 system

Type of coverage:
open
Controls:
other: negative (Milli-Q water) and positive (8N KOH) control
Amount / concentration applied:
TEST MATERIAL
The skin was moistened with 25 μl Milli-Q water (Millipore Corp., Bedford, Mass., USA) to ensure close contact of the test item to the tissue and 38.7 to 43.4 mg of the solid test item (with a glass weight boat) was added into the 6-well plates on top of the skin tissues.

NEGATIVE CONTROL (Milli-Q water) : 50 μl

POSITIVE CONTROL (8N KOH) : 50 μl
Duration of treatment / exposure:
3 minutes and 1 hour
Observation period:
not relevant for this type of test
Number of animals:
4 tissues per test item, negative control and positive control: 2 for the 3-minute exposure and 2 for the 1 hour-exposure
Details on study design:
CELL CULTURE
- Tissues: on the day of receipt the tissues were kept on agarose and stored in the refrigerator. On the next day, at least one hour before starting the assay the tissues were transferred to 6-well plates with 0.9 mL DMEM medium (Dulbecco’s Modified Eagle’s Medium) (supplemented DMEM medium, serum-free supplied by MatTek Corporation).
- MTT medium: MTT concentrate (5 mg/mL) diluted (1:5) with MTT diluent (supplemented DMEM). Both supplied by MatTek Corporation.

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.

TEST FOR COLOUR INTERFERENCE BY THE TEST ITEM
The test item was checked for possible colour interference before the study was started. Some non-coloured test items may change into coloured substances in aqueous conditions and thus stain the skin tissues during the 1-hour exposure. To assess the colour interference, approximately 25 mg of the test item or 50 μl Milli-Q water as a negative control were added to 0.3 ml Milli-Q water. The mixture was incubated for approximately 1 hour at 37.0 ± 1.0°C in the dark. At the end of the exposure time the mixture was shaken and it was checked if a blue / purple colour change was observed.

TEST FOR REDUCTION OF MTT BY THE TEST ITEM
The test item was checked for possible direct MTT reduction before the study was started. To assess the ability of the test item to reduce MTT, approximately 25 mg of the test item was added to 1 ml MTT (Sigma, Zwijndrecht, The Netherlands) solution (1 mg/ml) in phosphate buffered saline. The mixture was incubated for approximately 1 hour at 37.0 ± 1.0ºC. A negative control, sterile Milli-Q water was tested concurrently. At the end of the exposure time it was checked if a blue / purple colour change was observed.

APPLICATION/TREATMENT OF THE TEST ITEM
The skin tissues were kept in the refrigerator the day they were received. The next day, at least 1 hour before the assay was started the tissues were transferred to 6-well plates containing 0.9 ml DMEM medium per well. The level of the DMEM medium was just beneath the tissue. The plates were incubated for approximately 2 hours at 37.0 ± 1.0ºC. The medium was replaced with fresh DMEM medium just before the test item was applied. After the exposure period, the tissues were washed with phosphate buffered saline (Invitrogen Corporation, Breda, The Netherlands) to remove residual test item Rinsed tissues were kept in 24 well plates on 300 μl DMEM medium until 6 tissues (= one application time) were dosed and rinsed.

CELL VIABILITY MEASUREMENT
The DMEM medium was replaced by 300 μl MTT-medium and tissues were incubated for 3 hours at 37°C in air containing 5% CO2. After incubation the tissues were washed with PBS and formazan was extracted with 2 mL isopropanol (MatTek corporation) over night at room temperature. The amount of extracted formazan was determined spectrophotometrically at 570 nm in triplicate with the TECAN Infinite® M200 Pro Plate Reader.

Cell viability was calculated for each tissue as percentage of the mean of the negative control tissues. Skin corrosion potential of the test item was classified according to remaining cell viability following exposure of the test item with either of the two exposure times.

ELECTRONIC DATA CAPTURE
- REES Centron Environmental Monitoring system version SQL 2.0 (REES Scientific, Trenton, NJ, USA) for temperature and humidity.
- Magellan Tracker 7.0 (TECAN, Austria) for optical density measurement.

INTERPRETATION
A test item is considered corrosive in the skin corrosion test if:
a) The relative mean tissue viability obtained after the 3-minute treatment compared to the negative control tissues is decreased below 50%.
b) In addition, a test item considered non-corrosive (viability ≥ 50%) after the 3-minute treatment is considered corrosive if the relative tissue viability after 1-hour treatment with the test item is decreased below 15%.

A test item is considered non-corrosive in the in vitro skin corrosion test if:
a) The relative mean tissue viability obtained after the 3-minute treatment compared to the negative control tissues is not decreased below 50%.
b) In addition, the relative tissue viability after the 1-hour treatment is not decreased below 15%.

Results and discussion

In vitro

Resultsopen allclose all
Irritation / corrosion parameter:
% tissue viability
Run / experiment:
3-minute application
Value:
71
Vehicle controls validity:
not applicable
Negative controls validity:
valid
Positive controls validity:
valid
Remarks on result:
other: individual tissue viability: 66 and 76
Irritation / corrosion parameter:
% tissue viability
Run / experiment:
1-hour application
Value:
8
Vehicle controls validity:
not applicable
Negative controls validity:
valid
Positive controls validity:
valid
Remarks on result:
other: individual tissue viability: 7 and 8
Irritation / corrosion parameter:
other: optical density
Run / experiment:
3-minute application
Value:
1.346
Vehicle controls validity:
not applicable
Negative controls validity:
valid
Positive controls validity:
valid
Remarks on result:
other: individual values: 1.243 and 1.449
Irritation / corrosion parameter:
other: optical density
Run / experiment:
1-hour application
Value:
0.159
Vehicle controls validity:
not applicable
Negative controls validity:
valid
Positive controls validity:
valid
Remarks on result:
other: individual values: 0.148 and 0.170
Other effects / acceptance of results:
The relative mean tissue viability obtained after the 3-minute and 1-hour treatments with the test item compared to the negative control tissues was 71% (66 and 76%) and 8% (7 and 8%) respectively. Because the mean relative tissue viability for the test item was below 15% after 1 hour treatment it is considered to be corrosive.

Any other information on results incl. tables

The test item was checked for colour interference in aqueous conditions and possible direct MTT reduction by adding the test item to MTT medium. Because the 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.

The absolute mean OD570 (optical density at 570 nm) of the negative control tissues was within the laboratory historical control data range. The mean relative tissue viability following 3-minute exposure to the positive control was 11% (9 and 13%) and 7% (4 and 10%) after 1 hour exposure.

The maximum inter-tissue variability in viability between two tissues treated identically was less than 15% and the maximum difference in percentage between the mean viability of two tissues and one of the two tissues was less than 8% for the negative control and test item. For the positive control, the maximum inter-tissue variability in viability between two tissues treated identically was less than 53% and the maximum difference in percentage between the mean viability of two tissues and one of the two tissues was less than 36%, however since the viabilities were below 20% the acceptability criteria were met. It was therefore concluded that the test system functioned properly.

Applicant's summary and conclusion

Interpretation of results:
Category 1 (corrosive) based on GHS criteria
Conclusions:
This test was considered to be valid and the test item was concluded to be corrosive in the in vitro skin corrosion test under the experimental conditions described in the report.