Alkanoic acid and polyoxomolybdate borate alkanoate clusters

Skin irritation / corrosion

Administrative data

Endpoint:

skin corrosion: in vitro / ex vivo

Type of information:

experimental study

Adequacy of study:

key study

Study period:

October 2016

Reliability:

1 (reliable without restriction)

Rationale for reliability incl. deficiencies:

guideline study

Data source

Reference

Reference Type:

study report

Title:

Unnamed

Year:

2016

Report date:

2016

Materials and methods

Test guideline

Qualifier:

according to guideline

Guideline:

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

Version / remarks:

adopted 28 July 2015

Deviations:

no

GLP compliance:

yes (incl. QA statement)

Remarks:

signed on 23 October 2015

Test material

Test material information

Constituent 1

Test material form:

liquid: viscous

In vitro test system

Test system:

artificial membrane barrier model

Vehicle:

unchanged (no vehicle)

Test animals

Details on test animals or test system and environmental conditions:

Not applicable - Since this is an in-vitro study there is no information on test animals.

Test system

Vehicle:

unchanged (no vehicle)

Amount / concentration applied:

500 mL of the test item were carefully layered , as supplied, onto the surface of the membrane barrier and evenly distributed.

Duration of treatment / exposure:

60 minutes

Observation period:

Not applicable

Number of animals:

Not applicable

Details on study design:

TEST SYSTEM:
- Test kit:
Commercially available kit CORROSITEX supplied by INT.E.G.R.A. Srl, batch n° CT060115

- Preparation of the bio-barrier:
The fully constructed membrane barriers were prepared the day before the beginning of the classification assay as follows:
- 0.40g of biobarrier matrix were weighed in a vial and 4.0 mL of an aqueous solution were added in order to prepare a 100mg/mL solution.
- The vial was palced inside a water bath container on a hot plate and heated to 68°c with mediu speed stirring using a micro stirbar to avoid foaming. The temperature of the water bath was measured by a thermometer and never exceeded 70°C.
- Approximately 8 minutes later, when the biobarrier matrix powder was completely dissolved, the heat was turned off and the vial let sit in the water bath for few minutes until beginning of next step.
- 200 µL were dispensed into each membrane disc using a micropipette.
- The gel was checked to be of equal thickness and density throughout, and with no air bubbles or defects that could affect its functional integrity.
- The plate containing the newly prepared biobarriers was wrapped with plactic wrap to avoid dehydration and immediately stored at + 4°C until used.

EXPERIMENTAL PERFORMANCE:
- Compatibility test:
Prior to performing the membrane barrier test, a compatibility test was performed to insure that the test item and the CDS reagent were compatible. The CDS is a measurement system that must respond to the presence of the test item.
In the system used in this study, the CDS was composed of a pH 7.0 aqueous solution of two pH indicator dyes. The acid indicator dye, methyl orange, changes colour when the pH of the solution drops below 4.5. The basic indicator dye, phenol red, changes colour when the pH rises above 8.5. Therefore acids and bases that enter the CDS are detected because they promote a visible change in the colour of these indicator dyes. Chemicals that do not cause the pH to change appreciably will not be qualified for the assay because they fail to provoke a colour change.
The compatibility test was achieved few days before beginning the classificaiton assay at ambient temperature by using a Qualify test tube containing an amber liquid corresponding to an aliquot of the CDS reagent.
150 µL of the test item were added, as supplied, to the Qualify test tube. The tube was shaken and observed for the presence of any detectable change (colour or consistency).
In this study, the colour of the test item was too intense, dark blue, and prevented for the observation of a change of colouring in the CDS: the resulting colour was the test item's colour itself. This is why an adapted procedure was used for the categorisation of the test item (procedure with pH measurements).

Timescale category test: pH procedure:
The intensively coloured test item should then be subjected to a timescale category test. This category allows to establish apprpriate timescale for the corrosivity classification assay of the test item. This step utilizes indicator solutions to permit categorization in Category 1, typically strong acids/bases, or Category 2, typically weak acids/bases.
The test tubes A and B contain solutions of different ph indicators causing the colour change depending on the pH and having their own transition areas.
Thi adapted procedure for intensively coloured itens consists in successive pH measurements.
First a 10%v/v aqueous solution of the test item was prepared adding 2 mL of the test item after being shaken to 18 mL of distilled water and mixing manually and by vortex. The solution is heated few minutes to be dissolved, it was a blue solution with blue micelles. The pH of this 10% solution was measured: 2.26. If the pH of the 10% test iten solution is < 7.0, the Tube A has to be used to perform the Categorisation test (Tube B is used if ph > 7.0).
150 µL of the test item after being shaken were added to the Tube A, containing a yellow liquid, at ambient temperature. The tube was shaken and the pH of the resulting solution was measured: 5.48. For measurements performed with Tube A, if the pH is ≤ 5 the sample is Category 1; if the pH is > 5 the sample is Category 2. The test item was consequently assigned to Category 2.

Classification assay:
- Assembly of the test method component:The membrane barriers were taken out of the refirgerator. Their integrity was carefully checked, and they were positioned in a previously labelled vial containing the CDS so that they were in full contact with the indicator solution with no air bubbles present. Membrane barrriers were not allowed to stan in the vial longer than 2 minutes before adding the test items. The study was performed at ambient temperature.
- Application of the test item: 500 µL of the test item were carefully layered , as supplied, onto the surface of the membrane barrier and evenly distributed. The time of applying the test item to the membrane was recorded. Four replicates were run staggered to ensure than short corrosion times were accurately recorded.
- Controls: Concurrent controls were included in single in this study:
* Negative control, non corrosive: 500 µL of a 6% propionic aicd solution
* Positive control, corrosive: sodium hydroxide.
A CDS colour control was also included in single.

Endpoints measured:
Each vial was appropriately monitored and the time of the first change in the indicator solution, i.e. barrier penetration, was recorded. The elaspsed time between application and penetration of the membrane biobarrier was determined.

Study acceptability criteria:
Zccording to the established time parameters for each of the GHS corrosivity subcategories, the time (in minutes) elapsed between applicatin of a test item to the membrane barrier and barrier penetration was used to predict the corrosivity of the test item. For a study to be considered acceptable, the concurrent positive control should give the expected penetration response time, the concurrent negative control should not be corrosive, and when included, the concurrent solvent control should neither be corrosive nor should it alter the corrosivity potential of the test item.
The CORROSITEX assay will be accepted if the positive control time falls within +/- two standard deviations of the positive control historical mean breakthrough time.

Interpretation of results:
The time in minutes elapsed between applicaiton of the test substance to the membrane barrier and barrier penetration was used to classify the test substance in terms of corrosivity, and, if applicable, UN Packing Group. Cut-off time values for each of the three corrosive subcategories were established for each proposed test method. Final decisions on cut-off times considered the need to minimize under-classification of corrosive hazard (i.e. false negative).

Results and discussion

In vitro

Results

Irritation / corrosion parameter:

penetration time (in minutes)

Value:

> 60

Negative controls validity:

valid

Positive controls validity:

valid

Remarks on result:

other: The test item did not disrupt the membrane after 60 minutes in the four replicates.

Other effects / acceptance of results:

The test item did not disrupt the membrane after 60 minutes in the four replicates.

As expected, the negative control (propionic acid 6%v/v) did not disrupt the mambrance and was not corrosive.

As expected, the positive control (sodium hydroxide) was found to be corrosive (GHS subcategory 1B) and disrupt the membrane after 14 minutes and 25 seconds.

Applicant's summary and conclusion

Interpretation of results:

other: not corrosive

Remarks:

Criteria used for interpretation of results: EU

Conclusions:

In accordance with Regulation EC 1272/2008, the test item does not have to be classified in category 1 'Corrosive'.