3-octoxypropane-1,2-diol

Skin irritation / corrosion

Administrative data

Endpoint:

skin corrosion: in vitro / ex vivo

Type of information:

experimental study

Adequacy of study:

key study

Study period:

09 Sep 2019 to 13 Sep 2019

Reliability:

1 (reliable without restriction)

Rationale for reliability incl. deficiencies:

guideline study

Data source

Reference

Reference Type:

study report

Title:

Unnamed

Year:

2019

Report date:

2019

Materials and methods

Test guideline

Test guideline 1

Qualifier:

according to guideline

Guideline:

OECD Guideline 431 (In Vitro Skin Corrosion: Reconstructed Human Epidermis (RHE) Test Method)

Version / remarks:

18 June 2019

Deviations:

no

Test guideline 2

Qualifier:

according to guideline

Guideline:

EU Method B.40 (In Vitro Skin Corrosion: Transcutaneous Electrical Resistance Test (TER))

Version / remarks:

31 may 2008

Deviations:

no

GLP compliance:

yes

Test material

Test material information

Constituent 1

Reference substance name:

3-(octyloxy)propane-1,2-diol

Cas Number:

10438-94-5

Molecular formula:

C11H24O3

IUPAC Name:

3-(octyloxy)propane-1,2-diol

Test material form:

liquid

Details on test material:

Storage Conditions: At room temperature protected from light container flushed with nitrogen.

In vitro test system

Test system:

human skin model

Source species:

human

Cell type:

other: epidermal keratinocytes

Cell source:

other: MatTek Corporation, Ashland MA, U.S.A.

Source strain:

other: not applicable

Vehicle:

unchanged (no vehicle)

Details on test system:

RECONSTRUCTED HUMAN EPIDERMIS (RHE) TISSUE
- Model used: EpiDerm Skin Model
- Tissue batch number(s): EPI-200, Lot no.: 30964 kits D and E
- Production date: 11 Sep 2019

TEMPERATURE USED FOR TEST SYSTEM
- Temperature used during treatment / exposure: 3 minutes at room temperature, 1 hour incubation at 37.0 ± 1.0ºC.
- Temperature of post-treatment incubation: All incubations, with the exception of the test item incubation of 3 minutes at room temperature, were carried out in a controlled environment, in which optimal conditions were a humid atmosphere of 62 - 88%, containing 5.0 ± 0.5% CO2 in air in the dark at 36.3 - 37.1°C

REMOVAL OF TEST MATERIAL AND CONTROLS
- Number of washing steps: one step, washing done with PBS
- Observable damage in the tissue due to washing: No
- Modifications to validated SOP: No

MTT DYE USED TO MEASURE TISSUE VIABILITY AFTER TREATMENT / EXPOSURE
- MTT concentration: MTT concentrate (5 mg/mL) diluted (1:5) with MTT diluent (supplemented DMEM).
- Incubation time: 3 hours
- Spectrophotometer: TECAN Infinite® M200 Pro Plate Reader
- Wavelength: 570 nm

NUMBER OF REPLICATE TISSUES:
- 4 tissues per test item together with a negative control and positive control. Two tissues were used for a 3-minute exposure and two for a 1-hour exposure period.
- For the negative and positive controls, 2 tissues were treated with 50 µL Milli-Q water (negative control) and 2 tissues were treated with 50 µL 8N KOH (positive control) for both the 3-minute and 1-hour time point.

ACCCEPTABILITY CRITERIA
The in vitro skin corrosion test is considered acceptable if it meets the following criteria:
a) The absolute mean OD570 of the two tissues of the negative control should reasonably be within the laboratory historical control data range and the acceptance limits of OECD431 (lower acceptance limit ≥0.8 and upper acceptance limit ≤2.8).
b) The mean relative tissue viability following 1-hour exposure to the positive control should be <15 %.
c) In the range 20 - 100% viability, the Coefficient of Variation (CV) between tissue replicates should be ≤30%.

DECISION CRITERIA
The test substance is considered to be corrosive to skin if:
- The relative mean tissue viability obtained after 3-minute treatment compared to the negative control tissues is decreased below 50%
- In addition, a test item considered non-corrosive (viability ≥ 50%) after the 3-minute treatment is considered corrosive if the relative tissue viability after 1-hour treatment with the test item is decreased below 15%.
A test item is considered non corrosive in the in vitro skin corrosion test if:
- The relative mean tissue viability obtained after the 3-minute treatment compared to the negative control tissues is not decreased below 50%.
- In addition, the relative tissue viability after the 1-hour treatment is not decreased below 15%.

Control samples:

yes, concurrent negative control

yes, concurrent positive control

Amount/concentration applied:

TEST MATERIAL
- Amount applied: 50 µL of the undiluted test item was added into the 6-well plates on top of the skin tissues

VEHICLE
Not applicle

Duration of treatment / exposure:

3 minutes and 60 minutes

Number of replicates:

2

Results and discussion

In vitro

Results

Results 1

Irritation / corrosion parameter:

% tissue viability

Run / experiment:

3 minutes treatment

Value:

58

Vehicle controls validity:

not applicable

Negative controls validity:

valid

Positive controls validity:

valid

Remarks:

mean tissue viability: 17%

Results 2

Irritation / corrosion parameter:

% tissue viability

Run / experiment:

1 Hour treatment

Value:

78

Vehicle controls validity:

not applicable

Negative controls validity:

valid

Positive controls validity:

valid

Remarks:

mean tissue viability: 11%

Other effects / acceptance of results:

- OTHER EFFECTS:
- Visible damage on test system: no
- Direct-MTT reduction: no
- Colour interference with MTT: no

ACCEPTANCE OF RESULTS:
- Acceptance criteria met for negative control:
The absolute mean OD570 (optical density at 570 nm) of the negative control tissues was 1.599 after the 3 minute treatment and 1.497 after the 1 hour treatement which was within the acceptance limits of OECD 431 (lower acceptance limit ≥0.8 and upper acceptance limit ≤2.8) and the laboratory historical control data range (3 min treatment 1.258 - 2.615; 1 hour treatment 1.371 - 2.371).
- Acceptance criteria met for positive control:
The mean relative tissue viability following the 1-hour exposure to the positive control was 11%.
- Acceptance criteria met for variability between replicate measurements:
In the range of 20 - 100% viability the Coefficient of Variation between tissue replicates was ≤ 17%, indicating that the test system functioned properly.

Any other information on results incl. tables

Table1          
Mean Absorption in the in vitro Skin Corrosion Test with the test item

	3-minute application					1-hour application
	A (OD570)	B (OD570)	Mean (OD570)		SD	A (OD570)	B (OD570)	Mean (OD570)		SD
Negative control	1.653	1.545	1.599	±	0.076	1.480	1.513	1.497	±	0.023
Test item	0.833	1.008	0.920	±	0.123	1.094	1.253	1.174	±	0.1130
Positive control	0.237	0.305	0.271	±	0.048	0.191	0.134	0.162	±	0.041

SD = Standard deviation

Duplicate exposures are indicated by A and B.

Table2          
Mean Tissue Viability in the in vitro Skin Corrosion Test with the test item

	3-minute application viability (percentage of control)	1-hour application viability (percentage of control)
Negative control	100	100
Test item	58	78
Positive control	17	11

 

Table3          
Coefficient of Variation between Tissue Replicates

	3 minute	1 hour
Negative control	6.5	2.2
Test item	17	13
Positive control	22	30

CV (%) = 100 - [(lowest OD₅₇₀/highest OD₅₇₀) x 100%]

Applicant's summary and conclusion

Interpretation of results:

other: not corrosive

Remarks:

According to Regulation (EC) No. 1272/2008 and its amendments.

Conclusions:

The results of an in vitro skin corrosion test performed according to OECD TG 431 showed that the substance was not corrosive to the skin.

Executive summary:

An in vitro skin corrosion test was performed following OECD TG 413 and in accordance with GLP principles. The test item was applied undiluted (50 µL) directly on top of the skin tissue for 3 minutes or 1 hour. After exposure the skin tissue is thoroughly rinsed to remove the test item followed by an immediate determination of the cytotoxic effect using MTT.

The positive control had a mean relative tissue viability of 11% after the 1-hour exposure. The absolute mean OD₅₇₀(optical density at 570 nm) of the negative control tissues waswithin the acceptance limits of OECD 431 (lower acceptance limit ≥0.8 and upper acceptance limit≤2.8) and the laboratory historical control data range. In the range of 20 - 100% viability the Coefficient of Variation between tissue replicates was ≤ 17%,indicating that the test system functioned properly. The relative mean tissue viability obtained after 3-minute and 1-hour treatments with Saskine TM 80 compared to the negative control tissues was 58% and 78%, respectively. Because the mean relative tissue viability was not below 50% after the 3-minute treatment and not below 15% after the 1-hour treatment the substance is considered to be not corrosive.