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Toxicological information

Skin irritation / corrosion

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Administrative data

Endpoint:
skin corrosion: in vitro / ex vivo
Type of information:
experimental study
Adequacy of study:
key study
Study period:
2018-11-20 (experimental phase)
Reliability:
1 (reliable without restriction)
Rationale for reliability incl. deficiencies:
guideline study
Remarks:
GLP

Data source

Reference
Reference Type:
study report
Title:
Unnamed
Year:
2019
Report Date:
2019

Materials and methods

Test guideline
Qualifier:
according to
Guideline:
OECD Guideline 435 (In Vitro Membrane Barrier Test Method for Skin Corrosion)
Version / remarks:
OECD Guidelines for the Testing of Chemicals, Part 435, adopted 28. Jul. 2015
“In Vitro Membrane Barrier Test Method for Skin Corrosion”
Deviations:
no
GLP compliance:
yes (incl. certificate)

Test material

Reference
Name:
Unnamed
Type:
Constituent
Test material form:
liquid
Specific details on test material used for the study:
The test item was stored in the test facility in a closed vessel at room temperature (20 ± 5°C).

In vitro test system

Test system:
artificial membrane barrier model
Source species:
other: not applicable, this proteinaceous gel is composed of protein, e.g., keratin, collagen, or mixtures of pro-teins.
Cell type:
other: not applicable
Details on animal used as source of test system:
not applicable
Justification for test system used:
This test allows the identification and subcategorisation of 2-Butyne-1,4-diol, reaction products with 1,2-oxathiolane 2,2-dioxide and sodium hydroxide (HBOPS-Na) into the three GHS subcategories of corrosivity and the three UN Transport Packing Groups for corrosivity hazard. The classification assigned is based on the time it takes a substance to penetrate through the membrane barrier to the indicator solution.
Vehicle:
unchanged (no vehicle)
Details on test system:
SOURCE AND COMPOSITION OF MEMBRANE BARRIER USED
- Was the Corrositex® test kit used: yes
- Components: Specification: Commercially available Corrositex®-Kit
The test system consists of two components: a proteinaceous macromolecular gel (=synthetic biobarrier) on a permeable membrane and a fluid, the Chemical Detection System (CDS). Corrosive substances are able to penetrate the biobarrier and can enter into the CDS. A colour change is visible due to a pH indicator dye.
The proteinaceous gel, composed of protein, e.g., keratin, collagen, or mixtures of proteins, forming a gel matrix, serves as the target for the test item. The proteinaceous material is placed on the surface of the supporting membrane and allowed to gel prior to placing the membrane barrier over the indicator solution.
The indicator solution responds to the presence of a test item. A combination of pH indicator dyes that will show a colour change in response to the presence of the test item or other types of chemical or electrochemical reactions is used.
The time required for a test item to pass through a biobarrier membrane is inversely proportional to its corrosivity: the more corrosive a substance, the shorter is the time required to cause a colour change.
Non-corrosive substances do not penetrate the biobarrier at all or too slowly in order to classify them as corrosive according the UN packing groups and the GHS.
Origin: Corrositex®-Kit was produced by InVitro International, USA, 17751 Sky Park East, Suite G, Irvine, CA 92614 and procured by Romer Labs Deutschland GmbH.
Day of delivery: 13. Nov. 2018
Batch Corrositex®-Kit: CT061118
Chemicals and Solutions
The Corrositex®-Kit is procured by Romer Labs Deutschland GmbH and contains the following substances:
Biobarrier Matrix Powder: The biobarrier is available as a matrix powder. As soon as it is dissolved in the biobarrier matrix diluent, it develops to a proteinaceous macromolecular gel (= synthetic biobarrier). This proteinaceous gel is composed of protein, e.g., keratin, collagen, or mixtures of proteins.
Biobarrier Matrix Diluent: Diluent for dissolving the biobarrier matrix powder.
Confirmation Reagent: Reagent used for confirmation of the category of the test item in the context of the “Categorisation screen”
Chemical Detection System: The Chemical Detection System (CDS) is an indicator solution with a pH indicator combination of dyes that will show a colour change in response to the presence of the test item or other types of chemical or electrochemical reactions.
Buffer Solutions for Categorisation of the Test Item:
Categorize A solution is composed of 0.1-M (Na+/H+) MOPSO and 10 mg/mL methyl red, pH 7.0.
Categorize B solution is composed of 0.05-M (Na+/H+) HEPES and 100 mg/mL o-cresolphthalein, pH 7.0.
- Apparatus and preparation procedures: Production of the Biobarrier
The biobarrier was produced on the day the assay was performed.
The entire contents of the biobarrier diluent vial were added slowly to the matrix powder to ensure complete and uniform solubilisation. The vial containing the solution was placed in a water bath on a heating plate set to 68°C with the stir switch set to maintain 200 rpm for the stir bar. The solution was warmed to 68 °C and stirred for 20 min to solubilise the biobarrier matrix. Then the heating plate was switched off and the solution was left to stand for 10 minutes. In the next step 200 µL of the solubilised matrix were then pipetted onto the membrane discs.
The membrane discs with the biobarrier were stored in the fridge (2-8°C) for at least 2 hours before use.

WAS THE COMPATIBILITY TEST PERFORMED:
For the qualification screen, 150 µL of the test item were added to the “qualification test tube”.
The test item induced a colour change immediately (within 1 minute) in the CDS and is therefore qualified for the determination of its skin corrosion potential with the Corrositex®-Test.

WAS THE TIMESCALE CATEGORY TEST PERFORMED:
The categorisation screen was used to choose the appropriate scoring scale for the prediction model. The screen aimes to allocate the test item in Category 1 or 2 as indicated in the guideline, i.e. test chemicals with high (Cat. 1) or low (Cat. 2) acid/alkaline reserve.
The screen was performed by adding 150 µL of the test item to two different test tubes (A and B) which contained an acid resp. a base buffer.
The content of the individual tubes was then mixed and the resulting colours were observed after one minute.
Since no colour change could be observed in either tube, two drops of the “confirm reagent” were added to tube B; this was mixed and the resulting colour was used to confirm the category.
The categorisation kit and colour chart provided by Romer Labs Deutschland GmbH were used to determine the category.
The test item was classified in category 2.

METHOD OF DETECTION
- Indicator solution / Dye(s) used:
Categorize A solution is composed of 0.1-M (Na+/H+) MOPSO and 10 mg/mL methyl red, pH 7.0.
Categorize B solution is composed of 0.05-M (Na+/H+) HEPES and 100 mg/mL o-cresolphthalein, pH 7.0.
- Chemical or electrochemical detection system: chemical

METHOD OF APPLICATION:
The test item was used neat. Four replicates were tested.
500 µL of the liquid test item were applied directly on the biobarrier.
First, one vial was exposed to the test item and a stop watch was started. The vial was observed for 3 minutes continuously.
Since no colour change or any other change in the CDS was visible within 3 minutes, the remaining 3 vials were exposed to the test item in 1-minutes intervals.
Since the test item was classified as a category 2 substance, the vials were observed for maximally 60 minutes.

NUMBER OF REPLICATES: 4

NUMBER OF INDEPENDENT EXPERIMENTS TO DERIVE FINAL PREDICTION: 1

PREDICTION MODEL / DECISION CRITERIA (choose relevant statement)
- The test substance is considered to be corrosive to skin if < 60 min elapsed between application of the test substance to the membrane barrier and barrier penetration.
Assessment Test Items Category 2
Corrosivity GHS classification UN Packing Group H-Sentence Mean Time
Corrosive 1A I 314 0 - 3 min
Corrosive 1B II 314 > 3 – 30 min
Corrosive 1C III 314 > 30 – 60 min
Non-corrosive -- -- -- > 60 min

- Justification for the selection of the cut-off point(s): Classification according to ECVAM DB-ALM: INVITTOX protocol: “CORROSITEX® Continuous Time Monitor Assay”, INVITTOX no. 116
Control samples:
yes, concurrent negative control
yes, concurrent positive control
Amount/concentration applied:
TEST MATERIAL
- Amount(s) applied (volume or weight with unit): 500 µL
- Concentration (if solution): neat

NEGATIVE CONTROL
- Amount(s) applied (volume or weight): 500 µL 10% citric acid solution
- Concentration (if solution): 10% citric acid

POSITIVE CONTROL
- Amount(s) applied (volume or weight): one pellet of 114.6 mg of sodium hydroxide
- Concentration (if solution): neat
Duration of treatment / exposure:
60 minutes
Duration of post-treatment incubation (if applicable):
n/a
Number of replicates:
Negative control (1 vial), 10% citric acid solution
Positive control (1 vial), sodium hydroxide (used as solid)
Blank for CDS (1 vial)
Test item (4 vials)

Test system

Type of coverage:
open
Preparation of test site:
other: not applicable

Results and discussion

In vitro

Resultsopen allclose all
Irritation / corrosion parameter:
penetration time (in minutes)
Run / experiment:
mean
Value:
54
Vehicle controls validity:
not applicable
Negative controls validity:
valid
Positive controls validity:
valid
Irritation / corrosion parameter:
penetration time (in minutes)
Run / experiment:
Vial 1
Value:
53
Vehicle controls validity:
not applicable
Negative controls validity:
valid
Positive controls validity:
valid
Irritation / corrosion parameter:
penetration time (in minutes)
Run / experiment:
Vial 2
Value:
51
Vehicle controls validity:
not applicable
Negative controls validity:
valid
Positive controls validity:
valid
Irritation / corrosion parameter:
penetration time (in minutes)
Run / experiment:
Vial 3
Value:
58
Vehicle controls validity:
not applicable
Negative controls validity:
valid
Positive controls validity:
valid
Irritation / corrosion parameter:
penetration time (in minutes)
Run / experiment:
Vial 4
Value:
54
Vehicle controls validity:
not applicable
Negative controls validity:
valid
Positive controls validity:
valid
Irritation / corrosion parameter:
penetration time (in minutes)
Run / experiment:
Negative Control
Value:
> 61
Vehicle controls validity:
not applicable
Negative controls validity:
valid
Positive controls validity:
valid
Irritation / corrosion parameter:
penetration time (in minutes)
Run / experiment:
Positive Control
Value:
10
Vehicle controls validity:
not applicable
Negative controls validity:
valid
Positive controls validity:
valid
Other effects / acceptance of results:
- OTHER EFFECTS:
- Visible damage on test system:
none stated

ACCEPTANCE OF RESULTS:
- Acceptance criteria met for negative control: yes
- Acceptance criteria met for positive control: yes
- Range of historical values if different from the ones specified in the test guideline:
Parameter Negative Control Positive Control
Substance 10% Citric acid Sodium hydroxide
Mean break-through time no break-through 13 min
Standard deviation -- 3 min
Range (min – max) no break-through 8 – 19 min
Range (validity) no break-through 8 - 16 min
Present study no break-through 10 min

Applicant's summary and conclusion

Interpretation of results:
Category 1C (corrosive) based on GHS criteria
Conclusions:
The study was conducted under GLP according to OECD guideline 435 on the registered substance itself. The method is to be considered scientifically reasonable with no deficiencies in documentation or any deviations, the validity criteria are fulfilled, positive and negative controls gave the appropriate response. The substance was tested in the form in which it is distributed, i.e. the marketed aqueous solution. Hence, the results can be considered as reliable to assess the corrosive potential of HBOPS-Na as distributed and to determine the correct packaging group and GHS corrosion subcategory. The measured mean break-through time of the test item was 54 minutes. The test item is considered corrosive to skin and is classified to UN Packing Group III / GHS skin corrosion category 1C.
Executive summary:

One valid experiment was performed in this OECD TG 435 study under GLP.

Four vials with a synthetic biobarrier and a Chemical Detection System (CDS) were treated with the test item 2-Butyne-1,4-diol, reaction products with 1,2-oxathiolane 2,2-dioxide and sodium hydroxide (HBOPS-Na) (50% in water).

500 µL of the liquid test item were applied to each biobarrier and observed for possible penetration.

10% Citric acid was used as negative control and sodium hydroxide (NaOH) was used as positive control. The controls showed the expected results: The negative control showed no break-through within the observation time. The positive control showed clear corrosive effects after 10 minutes and is consequently classified as a corrosive substance belonging to UN Packing Group II.

The measured mean break-through time of the test item was 54 minutes.

In conclusion, it can be stated that in this study and under the experimental conditions reported, the test item possesses skin corrosion potential and is classified as a corrosive substance belonging to UN Packing Group III, GHS classification: 1C.

Therefore, 2-Butyne-1,4-diol, reaction products with 1,2-oxathiolane 2,2-dioxide and sodium hydroxide (HBOPS-Na) (50% in water) is considered as corrosive to skin in the Corrositex® - Test.