Potassium ethanolate

Skin irritation / corrosion

Administrative data

Endpoint:

skin corrosion: in vitro / ex vivo

Type of information:

experimental study

Adequacy of study:

key study

Study period:

2012-08-30 - 2013-02-14

Reliability:

1 (reliable without restriction)

Rationale for reliability incl. deficiencies:

other: GLP and guideline compliant study, fully adequate for assessment.

Data source

Reference

Reference Type:

study report

Title:

Unnamed

Year:

2013

Report date:

2013

Materials and methods

Test guideline

Qualifier:

equivalent or similar to guideline

Guideline:

OECD Guideline 435 (In Vitro Membrane Barrier Test Method for Skin Corrosion)

Principles of method if other than guideline:

The Corrositex® Biobarrier Membrane is a test system consisting of a reconstituted collagen matrix. The assay is based on the time that is required for the test substance to penetrate through the Corrositex® Biobarrier Membrane and producing a change in the Chemical Detection System (CDS). The Corrositex® assay is used to determine the corrosive potential of test substances. The assay is limited to testing those materials which cause detectable pH changes in the CDS.

GLP compliance:

yes (incl. QA statement)

Remarks:

BASF SE, Experimental Toxicology and Ecology, 67056 Ludwigshafen, Germany

Test material

Test material information

Constituent 1

Reference substance name:

Potassium ethanolate

EC Number:

213-029-0

EC Name:

Potassium ethanolate

Cas Number:

917-58-8

Molecular formula:

C2H6O.K

IUPAC Name:

potassium ethanolate

In vitro test system

Test system:

artificial membrane barrier model

Details on test system:

TEST SYSTEM
- Source: InVitro International, Irvine CA, USA

Experimental procedure
The experimental design of this study consisted of a qualification screen with the CDS (to determine if a color change can be detected) and a categorization screen (to categorize weak acids/bases and strong acids/bases), which were performed as a pretest, and a definitive Corrositex® assay. The Corrositex® assay was evaluated on the basis of the color change of the CDS. The time that a color change was observed was recorded manually and the break through times of the four replicates was used to determine the corrosive potential of the test substance.

Qualification screen
For the qualification screen, 100 mg of the test substance was added to the CDS screening tube. If the test substance failed to produce a color change in the CDS within one minute, the test substance could not be analyzed in this system, and no further testing was required.

Categorization screen
The categorization screen was used to assess the appropriate scoring scale for the test substance. The categorization screen was performed by adding 100 mg of test substance to each tube A and B. Each tube was mixed and the resulting color observed. If required, 2 drops of the "confirm" reagent were added to tube B, the tube mixed, and the resulting color observed. The categorization kit and color chart provided by InVitro International were used to determine the category. The test substance was scored as category 1 (high acid/alkaline reserve) or category 2 (low acid/alkaline reserve) as described in section 3.8.

Biobarrier preparation
The vial containing the biobarrier matrix powder was placed in a water bath at 64 – 68ºC. The entire content of the biobarrier diluent vial was added slowly to the matrix powder. The stir bar rotated slowly enough to avoid foaming of the solution. Two hundred μL of the solubilized matrix was pipetted into each of the membrane discs. The membrane discs were then refrigerated for at least 2 hours at 2 – 8ºC. The biobarriers were wrapped and stored at 2 – 8ºC for a maximum of 7 days. Any remaining matrix solution was stored at 2 – 8ºC for up to 30 days in order to prepare additional biobarrier membrane discs.

Corrositex® assay
Following the acceptance of the positive control the Corrositex® assay was performed for the test substance. Four vials containing the CDS were used for the test substance. In addition, one vial was used for the PC, NC and for the color (blank) control, each. A membrane disc coated with the biobarrier matrix was placed into one vial containing the CDS. Application of 500 mg was not possible due to the low specific weight of the test substance. Hence, approximately 400 mg of the test substance was added onto the membrane disc (=maximum applicable amount). An electronic time clock was started with the application. The vial was observed for three minutes for any change in the CDS. If no color change was observed within three minutes, the remaining membranes were treated with the test substance. An electronic time clock was started with each application. The vials were observed continuously for the first ten minutes. Thereafter the vials were observed for approximately ten minutes around the time points relevant for evaluation or until breakthrough of the test substance occurred. The elapsed time between test-substance application and the first change in the indicator solution (i.e. barrier penetration) was recorded. The positive control vial was prepared as described above and received one pellet of sodium hydroxide on top of the membrane disc. This vial was monitored continuously until breakthrough had occurred. The negative control vial was prepared as described above and received 500 μL of 10% citric acid. This vial was observed for 60 minutes and was evaluated as “non-corrosive” if no reaction had been observed.

Control samples:

other: Positive and negative control vials are included in the Corrositex kit.

Amount/concentration applied:

TEST MATERIAL
- Amount(s) applied: 400 mg

Duration of treatment / exposure:

Duration depends on the elapsed time between test substance application and the first change in the indicator solution. At least 3 min and up to 4 hours.

Number of replicates:

4

Test system

Vehicle:

unchanged (no vehicle)

Results and discussion

In vitro

Results

Irritation / corrosion parameter:

penetration time (in minutes)

Run / experiment:

mean breackthrough time (min)

Value:

ca. 3.5

Vehicle controls validity:

valid

Positive controls validity:

valid

Remarks on result:

other: exact mean breakthrough time (min:s): 3:32

Any other information on results incl. tables

Findings

Test substance	Break Through Time [min:s]
	Vial 1	Vial 2	Vial 3	Vial 4	Mean
12/0373-1	4:14	3:11	3:27	3:17	3:32
Controls:
PC: Sodium hydroxide, solid	8:44	-	-	-	-
NC: 10% citric acid	NB	-	-	-	-

Historical data

Historical period: Jun 2009 - Jun 2012

Number of studies performed: 31

	Mean [min:s]	SD [min:s]
PC (NaOH, solid)	12:06	2:39
NC (10% citric acid)	NB	-

NB = no breakthrough within maximum observation period (60 min)

Applicant's summary and conclusion

Interpretation of results:

Category 1B (corrosive)

Remarks:

Migrated information Criteria used for interpretation of results: EU