3-isocyanatomethyl-3,5,5-trimethylcyclohexyl isocyanate

Skin irritation / corrosion

Administrative data

Endpoint:

skin corrosion: in vitro / ex vivo

Type of information:

experimental study

Adequacy of study:

key study

Study period:

2016-01-18 to 2016-01-19

Reliability:

2 (reliable with restrictions)

Rationale for reliability incl. deficiencies:

guideline study with acceptable restrictions

Data source

Reference

Reference Type:

study report

Title:

Unnamed

Year:

2016

Report date:

2016

Materials and methods

Test guideline

Test guideline 1

Qualifier:

according to guideline

Guideline:

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

Version / remarks:

July 28, 2015, adopted

Test guideline 2

Qualifier:

according to guideline

Guideline:

other: ICCVAM Minimum Performance Standards: In Vitro Membrane Barrier Test Systems for Skin Corrosion, June 23, 2003

Test guideline 3

Qualifier:

according to guideline

Guideline:

other: ICCVAM Recommended Performance Standards for in vitro Test Methods for Skin Corrosion (May 2004)

GLP compliance:

yes (incl. QA statement)

Test material

Test material information

Constituent 1

Reference substance name:

3-isocyanatomethyl-3,5,5-trimethylcyclohexyl isocyanate

EC Number:

223-861-6

EC Name:

3-isocyanatomethyl-3,5,5-trimethylcyclohexyl isocyanate

Cas Number:

4098-71-9

Molecular formula:

C12H18N2O2

IUPAC Name:

5-isocyanato-1-(isocyanatomethyl)-1,3,3-trimethylcyclohexane

Test material form:

other: liquid

Details on test material:

Physical form: Colourless liquid

In vitro test system

Test system:

other: Membrane Barrier Test Kit "Corrositex™"

Details on test system:

Test Kit
Name: Corrositex™
Supplier: Transia GmbH, 35510 Butzbach, Germany
Lot No.: CT120314

Test system

Vehicle:

unchanged (no vehicle)

Amount / concentration applied:

- Test item: 500 μL of the neat test item were dispensed directly atop the bio-barrier.
- Positive control: Sulfuric acid (95-97%) was used as positive control. 500 μL were applied to only one bio-barrier.
- Negative control: Citric acid (10% (w/v) solution in deionised water) was used as negative control. 500 μL were applied to only one bio-barrier.
- Reference Item: 10% acetic acid (v/v) will be used as reference item. 500 μL were applied to four bio-barriers.

Duration of treatment / exposure:

Time until observable change in CDS solution: 0 - 240 min
As result from the categorisation test, the test item were applied per bio-barrier for 1 hour

Observation period:

1 hour

Details on study design:

Preparation of the Bio-barrier
- One day prior to testing the bio-barrier matrix was prepared.
- The bio-barrier powder was solved in the bio-barrier diluent and heated for 20 ± 2 minutes at 68 – 70 °C in a water bath under continuous stirring.
- The temperature did not exceed 70 °C. The mixture was allowed to cool in the turned-off water bath for another 10 minutes.
- The mixture was then filled into the membrane holders (200 μL per membrane holder). Air bubbles were avoided.
- The filled membrane holders were sealed with parafilm and were stored at 2 – 8 °C until further use.
Qualify Test
- In order to test whether the test system is suitable for the test item and reference item, 150 μL of the test item were applied into the
“Qualify Test Vial”. The vial was shaken until the solution appeared homogenous, and incubated for 1 minute. Afterwards, a change in consistency
was noted.
Categorisation Test
- In the categorisation test the observation period of the test item and reference item after application to the bio-barrier was determined:
• Category 1: observation period after application will be 4 hours
• Category 2: observation period after application will be 1 hour
- Approximately 150 μL of the test item were applied into the “Category A Vial” as well as into the “Category B Vial”. The vials were shaken until the
solution appeared homogenous. After 1 minute no colour change was monitored.
- Based on the colour change obtained, a test item is assigned to a category. If an intense colour change (similar to the category 1 colour chart) is
observed in “Category A Vial” or in “Category B Vial” the test item is assigned to category 1. If a less intense colour change (similar to the category 2 colour chart) is observed in “Category A Vial” or in “Category B Vial” the test item will be assigned to category 2. If no colour change is observed in
either of the vials, a confirmation test is conducted. For the confirmation test two drops of the confirm reagent are added to the “Category B Vial”.
The vial was shaken for 5 seconds. The colour of the solution matched one of the colours shown in the accompanying colour chart, confirming that
the test item is a category 2 substance.
Classification Test
- 11 vials containing the CDS were pre-warmed to room temperature.
- 4 vials each were used for quadruplicate measurement of the test item and reference item, the vial labelled (+) was used for the positive control
(single measurement), and the vial labelled (-) was used for the negative control (single measurement).
- The vial labelled C was used as colour reference for the CDS.
- Applications of the test item, reference item and the controls were performed staggered to ensure accurate reaction times to be recorded.
- The prepared bio-barriers were placed atop the CDS vials (not longer than 2 min prior to application) and 500 μL of the test item or controls,
respectively, were applied per bio-barrier for 1 hour was a result from the categorisation test.
- The time interval of the possible colour change or precipitation in the CDS solution was recorded in the raw data file.

Results and discussion

In vitro

Results

Irritation / corrosion parameter:

penetration time (in minutes)

Run / experiment:

Corrositex

Value:

> 60

Vehicle controls validity:

not specified

Negative controls validity:

valid

Positive controls validity:

valid

Remarks on result:

other: In conclusion, it can be stated that in this study and under the experimental conditions reported, the test item is not corrosive to skin.

Any other information on results incl. tables

RESULTS AND DISCUSSION

Qualify Test (Test Item)

The test item induced a physical change (precipitation) in the qualify test after 1 minute incubation. Since a physical change (precipitation) was visible in the “Qualify Test Vial”, the test item was considered to be suitable for the next step.

Qualify Test (Reference Item)

The reference item induced a change in colour in the qualify test after 1 minute incubation. Since a change in colour was visible in the “Qualify Test Vial”, the test item was considered to be suitable for the next step.

Categorisation Test (Test Item)

The test item did not induce a change in colour neither Category A vial nor in the Category B vial after 1 minute incubation. A confirmation experiment was performed by adding the confirm reagent to the Category B vial. This induced a change in colour to grey. Therefore, the test item was classified as category 2.

Categorisation Test (Reference Item)

The reference item did not induce a change in colour neither Category A vial nor in the Category B vial after 1 minute incubation. A confirmation experiment was performed by adding the confirm reagent to the Category B vial. This induced a change in colour to yellow. Therefore, the test item was classified as category 2.

 

Classification Test

 

Test Group	Time Interval of Color Change	UN GHS Prediction
Negative Control	> 60 minutes	Non-corrosive
Positive Control	53 seconds	Corrosive Sub-category 1A
Reference Item	> 30 – 60 minutes	Corrosive Sub-category1C
Test Item	> 60 minutes	Non corrosive

 

Discussion

According to Sponsor’s information there is an animal study available with test substance. Based on this study results test item has to be classified as corrosive. The design of this study could not distinguish between subcategories 1B and 1C. Therefore, a reference item, with well-known Category (1C) was determined in addition in the present study.

The test item and the reference item passed the qualify test and were considered as suitable for testing with the Corrositex™ test kit.

In the categorisation test the test item and the reference item did not induce a colour change in the category A or in the category B vial after 1 minute incubation. A confirmation experiment was performed by adding the confirm reagent to the Category B vial. This induced precipitation after 1 minute of incubation. The test item was classified according to Category 2.

500 μl of the test item and the reference item were applied on quadruplicate bio-barriers for the classification test. The bio-barriers were placed atop vials containing the CDS reagent. The time needed to corrode the bio-barrier and induce a distinct change in the colour of the CDS reagent was monitored for each of the vials.

500 μL of the negative control (10% citric acid) were placed atop one bio-barrier and the colour change of the CDS reagent was monitored up to 60 minutes.

500 μL of the positive control (Sulfuric acid (95-97%)) were placed atop one bio-barrier and the colour change of the CDS reagent was monitored.

The negative control did not induce a change in the colour of the CDS reagent after 60 minutes. The positive control showed a distinct change in the colour of the CDS reagent in the time interval of 0 – 3 minutes. These results ensured the validity of the test.

A change of colour of the CDS reagent after treatment of the bio-barriers with the test item could not be observed after 60 minutes. According to the classification criteria given in "overall remarks" the test item was classified as Non-Corrosive.

A change of colour of the CDS reagent after treatment of the bio-barriers with the reference item could be observed in the interval from 30 to 60 minutes. According to the classification criteria given in "overall remarks" the reference item was classified as corrosive (GHS Cat 1C).

Applicant's summary and conclusion

Conclusions:

In conclusion, it can be stated that in this study and under the experimental conditions reported, the test item is not corrosive to skin.

Executive summary:

This in vitro study was performed to assess the corrosive potential of test item by means of the in vitro Membrane Barrier Test for

Skin Corrosion (OECD TG 435) using the Corrositex™ test kit.

Following an initial determination of the compatibility of the test item with the test system (qualify test) and a test system-specific categorisation (categorisation test), 500 μL of the test item were applied on quadruplicate bio-barriers for the classification test. The

bio-barriers were placed atop vials containing the chemical detection system (CDS). The time needed to corrode the bio-barrier and to induce a distinct change in the colour of the CDS reagent was monitored for each of the vials.

Additionally to the test item a reference item was tested.

No change of colour of the CDS reagent after treatment of the bio-barriers with the test item was observed after the 60 minutes time interval.

A change of colour of the CDS reagent after treatment of the bio-barriers with the reference item could be observed in the interval from 30 to 60 minutes.

The test item as well as the negative and the positive controls fulfilled the acceptance criteria for the test system.

According to the classification criteria given in "overall remarks" the test item was, therefore, classified as not corrosive.

The reference item was classified as corrosive (UN GHS subcategory 1C or C; Reg. (EC) No. 1272/2008).

In conclusion, it can be stated that in this study and under the experimental conditions reported, the test item is not corrosive to skin.