Diisopentyl ether

Skin irritation / corrosion

Administrative data

Endpoint:

skin irritation: in vitro / ex vivo

Type of information:

experimental study

Adequacy of study:

key study

Study period:

2011

Reliability:

1 (reliable without restriction)

Rationale for reliability incl. deficiencies:

other: The study was performed according to the OECD guideline No.439 (July 2010) and in compliance with the GLP guidelines.

Data source

Reference

Reference Type:

study report

Title:

Unnamed

Year:

2012

Report date:

2012

Materials and methods

Test guideline

Qualifier:

according to guideline

Guideline:

OECD Guideline 439 (In Vitro Skin Irritation: Reconstructed Human Epidermis Test Method)

Deviations:

no

GLP compliance:

yes

Test material

Test material information

Constituent 1

Reference substance name:

Diisopentyl ether

EC Number:

208-857-4

EC Name:

Diisopentyl ether

Cas Number:

544-01-4

Molecular formula:

C10H22O

IUPAC Name:

3-methyl-1-(3-methylbutoxy)butane

Details on test material:

- Name of test material (as cited in study report): Diisopentyl ether
- Analytical purity: 99.2%
- Lot/batch No.: TAP 625
- Storage condition of test material: 2-8 °C

Test animals

Species:

other: In vitro human skin model

Strain:

other: EpiDerm model

Details on test animals or test system and environmental conditions:

TEST MATERIAL
- Test material: commercially available Epi-200-SIT-Kit
- Source: MatTek Corporation Ashland USA (first experiment), MatTek In Vitro Life Science Laboratories, Bratislava (Second experiment)
- Acclimation period: On the day of receipt the tissues were transferred to 12-well plates and preincubated with prewarmed Maintenance Medium for 24 hours at 37°C.

ENVIRONMENTAL CONDITIONS
- Temperature (°C): 37.1 – 37.4°C
- Humidity (%): 88 – 89% containing 5 +/- 0.5% CO2 in air
- Photoperiod (hrs dark / hrs light): dark

Test system

Type of coverage:

other: In vitro human skin model

Preparation of test site:

other: In vitro human skin model

Vehicle:

unchanged (no vehicle)

Controls:

other: other: Negative control: Phosphate buffered saline; positive control: 5% Sodium dodecyl sulphate in deionised H2O.

Amount / concentration applied:

Three tissues of the human skin model EpiDerm were treated with 30 µl diisopentyl ether.

Duration of treatment / exposure:

The skin tissues were exposed to diisopentyl ether for 60 minutes at 37°C.

Observation period:

Not applicable

Number of animals:

Not applicable (in vitro study)

Details on study design:

The purpose of this study was to determine skin irritation potential of diisopentyl ether using the in-vitro human epidermal model (EpiDerm). The test consists of a topical exposure of the neat test item to a human reconstructed epidermis model followed by a cell viability test. Cell viability is measured by dehydrogenase conversion of MTT (3-[4,5-dimethyl thiazole 2-yl]2,5-diphenyl-tetrazoliumbromide), present in cell mitochondria, into a blue formazan salt that is quantitatively meaured after extraction from tissues. The percent reduction of cell viability in comparison of untreated negative controls is used to predict skin irritation potential .

Protocol:
1- Pre-Tests: first, it was tested whether the test item is compatible with the EpiDerm test system. No reaction with reagens or materials was observed and therefore this protocol was considered suitable for the determination of the skin irritation potential of diisopentyl ether.
2- Pre-incubation: Skin tissues were pre-incubated to test their viability.
3- Treatment: Pre-incubated tissues were treated with buffer (negative control), SDS solution (positive control) or diisopentyl ether. Hereafter the tissues were incubated for 60 minutes. After the incubation period, the tissues were rinsed, dried and then transferred into a new plate with fresh asay medium. After a total post-incubation period of 42 hours, the cytotoxic effect was measured by determination of the relative formazan production (photometric absorption at 570 nm). The photometric absorption of the negative controls is considered as 100%. The mean of the three replicates of test item and positive control, formazan production is calculated as % photometric absorption compared with the negative control. If the formazan production is < 50% in comparison to the control, the test item is considered as irritant. If >50%, the test item is considered as non-irritant.
Two independant experiments were performed.

Results and discussion

In vitro

Results

Results 1

Irritation / corrosion parameter:

other: EpiDerm Model

Remarks:

Mean of three tissues

Run / experiment:

1

Value:

ca. 1.517

Vehicle controls validity:

valid

Negative controls validity:

valid

Positive controls validity:

valid

Remarks on result:

no indication of irritation

Results 2

Irritation / corrosion parameter:

other: Epiderm Model / Mean of three tissues

Run / experiment:

2

Value:

ca. 2.237

Vehicle controls validity:

valid

Negative controls validity:

valid

Positive controls validity:

valid

Remarks on result:

no indication of irritation

Other effects / acceptance of results:

After treatment, the absorbance values in the negative controls were within the required acceptability criterion. The positive control showed clear irritating effects. Variation within tissues was acceptable (<18%) for negative control, positive control and test item. In the first experiment the relative aabsorbance values were increased to 148.2% after the treatment with diisopentyl ether. In the second experiment, the relative absorbance values were increased to 151.8% after the treatment with the test item. Both values are well above the threshold for irritation potential (50%) but lie far above the value of the negative control, indicating an increased viability effect of the test item on the skin. It is clear that this effect is not caused by a direct interaction from the test substance with MTT since in the pre-test it was concluded that no interaction takes place.

Any other information on results incl. tables

Mean absorption values, Exp. 1

	Negative control	Diisopentyl ether	Positive control
Tissue 1	1.017	1.531	0.115
Tissue 2	1.024	1.518	0.111
Tissue 3	1.031	1.503	0.117
Mean of three tissues	1.024	1.517	0.114
Relative SD of the three tissues	0.7%	0.9%	2.7%

Mean absorption values, Exp. 2

	Negative control	Diisopentyl ether	Positive control
Tissue 1	1.493	2.226	0.079
Tissue 2	1.466	2.241	0.079
Tissue 3	1.463	2.245	0.095
Mean of three tissues	1.474	2.237	0.084
Relative SD of the three tissues	1.1%	0.4%	11.0%

Applicant's summary and conclusion

Interpretation of results:

not irritating

Remarks:

Migrated information Criteria used for interpretation of results: EU

Conclusions:

Diisopentyl ether is considered as not irritant in the Human Skin Model Test.

Executive summary:

A GLP compliant in-vitro study was performed according to OECD Guideline 439 in order to evaluate the potential of diisopentyl ether to evoke skin irritation in a human skin model. Two valid, independant experiments were performed. Three tissues of the human skin model EpiDerm were treated with diisopentyl ether for 60 minutes. After a post-incubation period, determination of the cytotoxic (irritancy) effect was performed. Cytotoxicity is expressed as the reduction of mitochondrial dehydrogenase activity measured by formazan production from MTT at the end of the treatment. DPBS-buffer was used as negative control, 5% SDS-solution was used as postive control.

After treatment, the absorbance values in the negative controls were within the acceptability criterion. The positive control showed clear irritating effects. In the first experiment the relative absorbance values were increased to 148.2% after the treatment with diisopentyl ether. In the second experiment, the relative absorbance values were increased to 151.8% after the treatment with the test item. Both values are well above the threshold for irritation potential (50%) and therefore it can be concluded that diisopentyl ether is not a skin irritant in the Human Skin Model Test.