1,3-diiodopropane

Skin irritation / corrosion

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

Test material information

Constituent 1

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

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

Results

Results 1

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

Results 2

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

Results 3

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

Results 4

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.