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Toxicological information

Skin irritation / corrosion

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Administrative data

Endpoint:
skin irritation: in vitro / ex vivo
Type of information:
experimental study
Adequacy of study:
key study
Study period:
2020
Reliability:
1 (reliable without restriction)
Rationale for reliability incl. deficiencies:
guideline study

Data source

Reference
Reference Type:
study report
Title:
Unnamed
Year:
2020
Report date:
2020

Materials and methods

Test guideline
Qualifier:
according to guideline
Guideline:
OECD Guideline 431 (In Vitro Skin Corrosion: Reconstructed Human Epidermis (RHE) Test Method)
Version / remarks:
18. Jun. 2019
Deviations:
no
GLP compliance:
yes (incl. QA statement)

Test material

Constituent 1
Chemical structure
Reference substance name:
1,3-diiodopropane
EC Number:
210-993-4
EC Name:
1,3-diiodopropane
Cas Number:
627-31-6
Molecular formula:
C3H6I2
IUPAC Name:
1,3-diiodopropane
impurity 1
Chemical structure
Reference substance name:
1-chloro-3-iodopropane
EC Number:
230-088-8
EC Name:
1-chloro-3-iodopropane
Cas Number:
6940-76-7
Molecular formula:
C3H6ClI
IUPAC Name:
1-chloro-3-iodopropane
impurity 2
Reference substance name:
Unknown Impurity
IUPAC Name:
Unknown Impurity
Test material form:
liquid
Details on test material:
Batch 90423 / CME0032526

In vitro test system

Test system:
human skin model
Source species:
human
Cell type:
non-transformed keratinocytes
Details on animal used as source of test system:
The test item is applied topically to a three-dimensional human skin model, comprising of non-transformed, human-derived epidermal keratinocytes, which have been cultured to form a multi-layered, highly differentiated model of the human epidermis. It consists of organized basal, spinous and granular layers, and a multi-layered stratum corneum con-taining intercellular lamellar lipid layers representing main lipid classes analogous to those found in vivo.
Vehicle:
water
Control samples:
yes, concurrent negative control
yes, concurrent positive control
Amount/concentration applied:
The liquid test item was applied without preparation (50 µL).
Duration of treatment / exposure:
3 minutes and 1 hour
Duration of post-treatment incubation (if applicable):
Following exposure to test item and removal thereof, the tissues were incubated with MTT solution for 3 hours at 37 ±1 °C and 5.0 ±1% CO2.
Number of replicates:
10 replicates for isopropanol (blank); for negative control, test item and positive control 2 tissues with 3 replicates each were measured.

Results and discussion

In vitro

Resultsopen allclose all
Irritation / corrosion parameter:
% tissue viability
Run / experiment:
Test item, 3 minutes incubation
Value:
78.2
Vehicle controls validity:
not applicable
Negative controls validity:
valid
Positive controls validity:
valid
Irritation / corrosion parameter:
% tissue viability
Run / experiment:
Test item, 1 hour incubation
Value:
100.1
Vehicle controls validity:
not applicable
Negative controls validity:
valid
Positive controls validity:
valid
Irritation / corrosion parameter:
% tissue viability
Run / experiment:
Positive control, 3 minutes incubation
Value:
13.9
Vehicle controls validity:
not applicable
Negative controls validity:
valid
Positive controls validity:
valid
Irritation / corrosion parameter:
% tissue viability
Run / experiment:
Positive control, 1 hour incubation
Value:
5.6
Vehicle controls validity:
not applicable
Negative controls validity:
valid
Positive controls validity:
valid

Any other information on results incl. tables

As blank, the optical density (OD 570 nm) of isopropanol (blank value) was measured in 12 wells of the 96-well-plate. The measured values and their mean are given in the following table:

Replicate

1

2

3

4

5

6

Mean

Absorbance

0.034

0.34

0.035

0.035

0.034

0.033

0.034

Replicate

7

8

9

10

11

12

Absorbance

0.034

0.034

0.034

0.033

0.033

0.035

 

The absorbance values (OD 570 nm) of negative control, test item and positive control are given in the following table:

Incubation

Negative Control

Test Item

Positive Control

Tissue 1

Tissue 2

Tissue 1

Tissue 2

Tissue 1

Tissue 2

3 min

2.042

1.900

1.622

1.404

0.315

0.281

1.985

1.894

1.634

1.453

0.316

0.285

2.000

1.886

1.632

1.450

0.317

0.284

1 h

1.684

1.675

1.770

1.582

0.117

0.126

1.670

1.677

1.779

1.586

0.129

0.129

1.668

1.689

1.767

1.591

0.124

0.128

 

From the measured absorbances, the mean absorbance of isopropanol was subtracted. The corrected mean and relative standard deviation (RSD) of the two tissues were also calculated.

Mean Absorbance Values of the 3 Minutes Experiment

Designation

Negative Control

Test Item

Positive Control

Mean – blank (tissue 1)

1.975

1.595

0.282

Mean – blank (tissue 2)

1.859

1.402

0.249

Mean of the two tissues

1.917

1.499

0.266

RSD

4.3%

9.1%

8.7%

 

Mean Absorbance Values of the 1 h Experiment

Designation

Negative Control

Test Item

Positive Control

Mean – blank (tissue 1)

1.640

1.738

0.089

Mean – blank (tissue 2)

1.646

1.552

0.094

Mean of the two tissues

1.643

1.645

0.092

RSD

0.3%

8.0%

3.3%

 

Comparison of Tissue Viability: For the test item and the positive control, the following percentage values of mean tissue viability were calculated in comparison to the mean of the negative controls:

Test Item

Positive Control

Incubation

78.2%

13.9%

3 min

100.1%

5.6%

1 h

 

Assessment and Validity

Corrosivity of the Test Item: The mean value of relative tissue viability of the test item was reduced to 78.2% after 3 minutes treatment. This value is above the threshold for corrosivity (50%). After 1 hour treatment, the mean value of relative tissue viability of the test item was increased to 100.1%, lying above the threshold for corrosivity (15%). Therefore, the test item is considered as non-corrosive to skin.

Validity: The criterion for optical density of the negative control (≥ 0.8 and ≤ 2.8) was fulfilled: optical density was 1.9 (3 minutes) and 1.6 (1 hour). The positive control showed clear corrosive effects. The criterion for the viability of the 1 hour experiment, expressed as % of the negative control (< 15%), was fulfilled, too. The mean value of relative tissue viability was 5.6%. The values for negative control and for positive control were within the range of historical data of the test facility.

Therefore, the experiment is considered valid.

Applicant's summary and conclusion

Interpretation of results:
GHS criteria not met
Conclusions:
The test item is considered non-corrosive to skin. After 3 minutes treatment, the mean value of relative tissue viability of the test item was reduced to 78.2%, well above the threshold for corrosivity (50%). After 1 hour treatment the mean value of relative tissue viability of the test item was increased to 100.1%, also well above the threshold for corrosivity (15%).
Executive summary:

One valid experiment, following OECD Guideline 431 and EU Method B.40-BIS, was performed. Two tissues of the human skin model EpiDerm™ were treated with the test item for 3 minutes and 1 hour, respectively. The test item was applied to each tissue and spread to match the tissue size. Demineralised water was used as negative control, 8 M KOH was used as positive control. After treatment, the respective substance was rinsed from the tissues. Then, cell viability of the tissues was evaluated by addition of MTT, which can be reduced to a blue formazan. Formazan production was evaluated by measuring the optical density (OD) of the resulting solution.

After treatment with the negative control, the absorbance values were within the required acceptability criterion of mean OD ≥ 0.8 and ≤ 2.8 for both treatment intervals thus, showing the quality of the tissues. The OD were 1.9 (3 minutes experiment) and 1.6 (1 hour experiment).

The positive control showed clear corrosive effects for both treatment intervals. The mean relative tissue viability value was reduced to 5.6% for the 1 hour treatment.

After 3 minutes treatment with the test item, the mean value of relative tissue viability was reduced to 78.2%. This value is above the threshold for corrosion potential (50%). After 1 hour treatment, the mean value of relative tissue viability was increased to 100.1%. This value is above the threshold for corrosion potential (15%).

Therefore, the test item 1,3-Diiodopropane is considered non-corrosive to skin in the Reconstructed Human Epidermis (RHE) Test Method.