3-(1-ethoxyethyl)-5-methyl-oxazolidin-2-one

Endpoint summary

Description of key information

The test substance does neither show a skin corrosion nor irritation potential.

The test substance shows an eye irritation potential.

Key value for chemical safety assessment

Skin irritation / corrosion

Link to relevant study records

Reference

Reference 1

Endpoint:

skin corrosion: in vitro / ex vivo

Type of information:

experimental study

Adequacy of study:

key study

Reliability:

1 (reliable without restriction)

Rationale for reliability incl. deficiencies:

guideline study

Qualifier:

according to guideline

Guideline:

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

Deviations:

no

GLP compliance:

yes (incl. QA statement)

Test system:

human skin model

Vehicle:

unchanged (no vehicle)

Details on test system:

Three-dimensional human epidermis model
The EpiDermTM model consists of normal, 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 containing intercellular lamellar lipid layers arranged in patterns analogous to those found in vivo. The EpiDermTM tissues (surface 0.6 cm²) are cultured on specially prepared cell culture inserts (MILLICELLs, 10 mm diameter) and commercially available as kits (EpiDerm™ 200) containing 24 tissues on shipping agarose.
Tissue model: EPI-200
Tissue Lot Number: 25800
Origin: MatTek In Vitro Life Science Laboratories, Bratislava, Slovakia
Several test substances were tested in parallel within the present test (test no. 90) by using the same control tissues (NC and PC).
Corrosion test:
From the day of arrival in the laboratory, tissues were kept in the refrigerator. At least 1 hour, but not more than 1.5 hours before test substance application, tissues were transferred to 6-well plates with 0.9 mL assay medium and preconditioned in the incubator at 37°C. The preincubation
medium was replaced by fresh medium immediately before application.
Two tissues per exposure time (3 minutes at room temperature or 1 hour in the incubator as a rule) and test group (test material, negative control and positive control; 12 tissues per test) were used.
Fifty microliters (50 μL) undiluted liquid test substance were applied by using a pipette. Control tissues were concurrently treated with 50 μL deionized water (NC) or with 50 μL 8 N potassium hydroxide (PC).
The tissues were washed with PBS to remove residual test material 3 minutes or 1 hour after start of the application treatment.
Rinsed tissues were kept in 24-well plates (holding plates) at room temperature on assay medium until all tissues per application time were dosed and rinsed. The assay medium was then replaced by MTT solution and tissues were incubated for 3 hours.
After incubation, the tissues were washed with PBS to stop the MTT incubation. The formazan that was metabolically produced by the tissues was extracted by incubation of the tissues in isopropanol. The optical density at a wavelength of 570 nm (OD570) of the extracts was
spectrophotometrically determined. Blank values were established of 4 microtiter wells filled with isopropanol for each microtiter plate.

Irritation / corrosion parameter:

% tissue viability

Run / experiment:

2 tissues were incubated for 3 minutes (corrosion test)

Value:

99.6

Vehicle controls validity:

not applicable

Negative controls validity:

valid

Positive controls validity:

valid

Irritation / corrosion parameter:

% tissue viability

Run / experiment:

2 tissues were incubated for 1 h (corrosion test)

Value:

68.9

Vehicle controls validity:

not applicable

Negative controls validity:

valid

Positive controls validity:

valid

Exposure period: 3 min (corrosion test)
Test substance identification		tissue 1	tissue 2	mean	SD	CV [%]
NC	mean OD570	1.610	1.671	1.641
	viability               [% of NC]	98.2	101.8	100.0	2.6	2.6
17/0010-1	mean OD570	1.615	1.652	1.634
	viability             [% of NC]	98.4	100.7	99.6	1.6	1.6
PC	mean OD570	0.114	0.216	0.165
	viability                [% of NC]	7.0	13.2	10.1	4.4	43.6

Exposure period: 1 h (corrosion test)
Test substance identification		tissue 1	tissue 2	mean	SD	CV [%]
NC	mean OD570	1.794	1.664	1.729
	viability            [% of NC]	103.8	96.2	100.0	5.3	5.3
17/0010-1	mean OD570	1.006	1.377	1.192
	viability            [% of NC]	58.2	79.7	68.9	15.2	22.0
PC	mean OD570	0.097	0.087	0.092
	viability           [% of NC]	5.6	5.0	5.3	0.4	7.7

Interpretation of results:

GHS criteria not met

Conclusions:

Based on the results observed and by applying the evaluation criteria described, it was concluded that 3-(1-Ethoxyethyl)-5-methyloxazolidin-2-on does not show a skin corrosion potential in the EpiDerm™ in vitro skin corrosion test under the test conditions chosen.

Reference 2

Endpoint:

skin irritation: in vitro / ex vivo

Type of information:

experimental study

Adequacy of study:

key study

Reliability:

1 (reliable without restriction)

Rationale for reliability incl. deficiencies:

guideline study

Qualifier:

according to guideline

Guideline:

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

Deviations:

no

GLP compliance:

yes (incl. QA statement)

Test system:

human skin model

Vehicle:

unchanged (no vehicle)

Details on test system:

Three-dimensional human epidermis model
The EpiDermTM model consists of normal, 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
containing intercellular lamellar lipid layers arranged in patterns analogous to those found in vivo. The EpiDermTM tissues (surface 0.6 cm²) are cultured on specially prepared cell culture inserts (MILLICELLs, 10 mm diameter) and commercially available as kits (EpiDerm™ 200)
containing 24 tissues on shipping agarose.
Tissue model: EPI-200
Tissue Lot Number: 25800 (Certificate of Analysis see appendix)
Origin: MatTek In Vitro Life Science Laboratories, Bratislava, Slovakia

Several test substances were tested in parallel within the present test (test no. 90) by using the same control tissues (NC and PC).
Irritation test:
On the day of arrival in the laboratory, the tissues were transferred to sterile 6-well plates with 0.9 mL assay medium and preconditioned in the incubator at 37°C. After 1 hour, the pre-incubation medium was replaced by fresh medium and preconditioning continued for 18 ± 3 hours.
Three tissues were treated with the test substance, the PC and the NC, respectively.
Thirty microliters (30 μL) undiluted liquid test substance were applied by using a pipette. Control tissues were concurrently treated with 30 μL sterile PBS (NC) or with 30 μL 5% SDS (PC). A nylon mesh was carefully placed onto the tissue surface afterwards.
The tissues were kept under the laminar flow hood at room temperature for 25 minutes overall and for 35 minutes in the incubator.
The tissues were washed with sterile PBS to remove residual test material 1 hour after start of application. Rinsed tissues were blotted on sterile absorbent paper and transferred into new 6-well plates pre-filled with 0.9 mL fresh medium. When all tissues were rinsed the surface of each tissue was carefully dried with a sterile cotton swab. Subsequently, the tissues were placed into the incubator at 37°C for 24 ± 2 hours.
After 24 ± 2 hours, the tissues were transferred into new 6-well plates pre-filled with 0.9 mL fresh medium and placed into the incubator for an additional 18 ± 2-hour post-incubation period. After the post-incubation period, the assay medium was replaced by 0.3 mL MTT solution and
the tissues were incubated in the incubator for 3 hours. After incubation, the tissues were washed with PBS to stop the MTT incubation. The formazan that was metabolically produced by the tissues was extracted by incubation of the tissues in isopropanol. The optical density at a wavelength of 570 nm (OD570) of the extracts was spectrophotometrically determined. Blank values were established of 4 microtiter wells filled with isopropanol for each microtiter plate.

Irritation / corrosion parameter:

% tissue viability

Run / experiment:

3 tissues were exposed for 1h + 24 h incubation of rinsed tissue + 18 h post-incubation

Value:

88.8

Vehicle controls validity:

not applicable

Negative controls validity:

valid

Positive controls validity:

valid

Results of the Irritation Test

Individual and mean OD570 values, individual and mean viability values, standard deviations and coefficient of variation

Test substance identification		tissue 1	tissue 2	tissue 3	mean	SD	CV [%]
NC	mean OD570	1.756	1.639	1.739	1.711
	viability [% of NC]	102.6	95.8	101.6	100.0	3.7	3.7
17/0010-1	mean OD570	1.365	1.614	1.579	1.519
	viability [% of NC]	79.8	94.3	92.3	88.8	7.9	8.9
PC	mean OD570	0.046	0.038	0.044	0.043
	viability [% of NC]	2.7	2.2	2.5	2.5	0.2	9.6

Interpretation of results:

GHS criteria not met

Conclusions:

Based on the results observed and by applying the evaluation criteria described, it was concluded that 3-(1-Ethoxyethyl)-5-methyloxazolidin-2-on does not show a skin irritation potential in the EpiDerm™ in vitro skin irritation test under the test conditions chosen.

Endpoint conclusion

Endpoint conclusion:

no adverse effect observed (not irritating)

Eye irritation

Link to relevant study records

Reference

Reference 1

Endpoint:

eye irritation: in vitro / ex vivo

Type of information:

experimental study

Adequacy of study:

key study

Reliability:

1 (reliable without restriction)

Rationale for reliability incl. deficiencies:

guideline study

Qualifier:

according to guideline

Guideline:

OECD Guideline 437 (Bovine Corneal Opacity and Permeability Test Method for Identifying i) Chemicals Inducing Serious Eye Damage and ii) Chemicals Not Requiring Classification for Eye Irritation or Serious Eye Damage)

Deviations:

no

GLP compliance:

yes (incl. QA statement)

Details on test animals or tissues and environmental conditions:

BCOP: Isolated bovine cornea: The test system is the isolated bovine cornea. Bovine eyes are obtained as a by-product of freshly slaughtered cattle (age of the animals: minimum 12 months, maximum 60 months).
Supplier: Schlachthof Mannheim, Mannheim, Germany

Vehicle:

unchanged (no vehicle)

Controls:

yes

Details on study design:

Experimental procedure BCOP Test
Several test substances were tested in parallel within the present test (test no. 222) by using the same control corneas (NC and PC).
Corneas free of defects (opacity, scratches, pigmentation etc.) were dissected with a 2 to 3 mm rim of sclera. Isolated corneas were mounted in cornea holders that consists of anterior and posterior chambers. Both chambers were filled to excess with pre-warmed Eagle’s MEM (without phenol red) and then equilibrated in a vertical position at about 32°C for at least 1 hour.
After the equilibration period, the medium in both chambers was replaced by fresh pre-warmed medium and initial corneal opacity readings were taken for each cornea with an opacitometer. Any corneas that showed macroscopic tissue damage or an opacity value < 550 opacity units were discarded. The remaining corneas were then distributed into negative control (NC), positive control (PC) and treatment groups.
Each corneal holder was uniquely identified with a number on the chambers.
Each treatment group (test substance, the NC and the PCs) consisted of 3 corneas. Before application, the medium in the anterior chamber was removed by using a syringe. 750 μL undiluted liquid test substance were applied into the anterior chamber by using a pipette.
For the control tissues, 750 μL deionized water (NC) or 750 μL 100% ethanol / 100% dimethylformamide (positive controls, PC1/PC2) were applied into the anterior chamber by using a pipette.
The corneas were incubated in a horizontal position at about 32°C for approximately 10 minutes (liquids and surfactants). The test substance, the NC and the PC were then removed from the anterior chamber by using a syringe and the epithelium was washed at least 3 times with Eagle’s MEM (containing phenol red) and once with Eagle’s MEM (without phenol red). Both chambers were then refilled with fresh Eagle’s MEM (without phenol red).
The corneas were incubated for 2 further hours at about 32°C. After the incubation period, the medium was removed and both chambers were then refilled with fresh Eagle’s MEM.
Before measurement, each cornea was visually observed and observations were recorded.
Final corneal opacity readings were taken for each cornea with an opacitometer.
For determination of permeability, the medium in the anterior chamber was replaced by 1 mL sodium fluorescein solution (4 mg/mL for liquid test substances and surfactants) and incubated for 90 ± 5 minutes in a horizontal position at about 32°C.
The amount of sodium fluorescein that permeated through the corneas into the posterior chamber was spectrophotometrically measured. Three aliquots per cornea were transferred to a 96-well microtiter plate and the optical density (OD490) was determined.

Irritation parameter:

in vitro irritation score

Value:

37

Vehicle controls validity:

not applicable

Negative controls validity:

valid

Positive controls validity:

valid

Test substance identification	Mean Opacity Value	Mean Permeability Value	Mean In Vitro IrritancyScore
17/0010-1	26.6	0.689	37.0
NC	4.2	0.001	4.2
PC1	29.1	0.642	38.7
PC2	90.1	0.222	93.5

Interpretation of results:

other: not identified as corrosive or severe irritant; no classification can be made for eye irritation, further testing with another suitable method is required

Conclusions:

Based on the results of the BCOP, and by applying the evaluation criteria, 3-(1-Ethoxyethyl)-5-methyloxazolidin-2-on was not identified as corrosive or severe irritant under the test conditions chosen.

Reference 2

Endpoint:

eye irritation: in vitro / ex vivo

Type of information:

experimental study

Adequacy of study:

key study

Reliability:

1 (reliable without restriction)

Rationale for reliability incl. deficiencies:

guideline study

Qualifier:

according to guideline

Guideline:

OECD Guideline 492 (Reconstructed Human Cornea-like Epithelium (RhCE) Test Method for Identifying Chemicals Not Requiring Classification and Labelling for Eye Irritation or Serious Eye Damage)

Deviations:

no

GLP compliance:

yes (incl. QA statement)

Details on test animals or tissues and environmental conditions:

The EpiOcularTM model (OCL-200) is a three-dimensional, non-keratinized tissue construct composed of normal human-derived, epidermal keratinocytes used to model the human corneal epithelium. The EpiOcularTM tissues (surface 0.6 cm²) are cultured on cell culture inserts (MILLICELLs, 10 mm in diameter) and are commercially available as kits (EpiOcular™ 200) containing 24 tissues on shipping agarose.
Tissue model: OCL-200
Tissue Lot Number: 23769
Supplier: MatTek In Vitro Life Science Laboratories, Bratislava, Slovakia

Vehicle:

unchanged (no vehicle)

Controls:

yes

Details on study design:

In order to assess the ability of the test material to directly reduce MTT, a pretest (experimental conduct in accordance with GLP, but without a GLP status) was performed. The test substance was added to 0.9 mL MTT solution. The mixture was incubated in the dark at about 37°C for 3 hours. A negative control (NC) (deionized water) was tested concurrently. If the MTT solution color or in case of water-insoluble test substances the border to the water-phase turned blue / purple the test substance was presumed to directly reduce MTT. The direct reduction of MTT by a test substance interferes with the color density produced by metabolic capacity of the tissue and would falsify the test results. In case of direct MTT reduction, two freeze-killed control tissues were treated with the test article and the NC each in the same way as described in the following section.

Several test substances were tested in parallel within the present test (test no. 84) by using the same control tissues (NC and positive control (PC)).
Two tissues were treated with each the test substance, the PC and the NC. There are two separate protocols for liquids and solids differing in exposure time and postincubation period. Due to the physical state of the test substance, the protocol for liquids was applied.
On the day of arrival in the laboratory, the tissues were transferred to sterile 6-well plates with 1 mL assay medium and preconditioned in the incubator at 37°C. After 1 hour, the pre-incubation medium was replaced by fresh medium and preconditioning continued in the incubator at standard culture conditions for 16 – 24 hours.
After pre-incubation, the tissues were pretreated with 20 μL PBS to wet the tissue surface. The tissues were incubated at standard culture conditions for 30 minutes.
By using a pipette, fifty microliters (50 μL) undiluted liquid test substance were applied covering the whole tissue surface. Control tissues were concurrently applied with 50 μL sterile deionized water (NC) or with 50 μL methyl acetate (PC).
After application, the tissues were placed into the incubator until the total exposure time of 30 minutes was completed.
In order to remove the test substance, the tissues were washed with sterile PBS. For this purpose, the tissues were immersed and swiveled three times in each of three beakers filled with PBS. Washed tissues were immediately immersed into 12-well plates pre-filled with 5 mL/well pre-warmed medium (post-soak immersion) to remove residual test substance.
After 12 minutes of post-soak immersion, each tissue was dried on absorbent paper and transferred to fresh 6-well plates filled with 1 mL/well pre-warmed medium. Subsequently, the tissues were incubated at standard culture conditions for 2 hours (postincubation period).
After the post-incubation period, the assay medium was replaced by 0.3 mL MTT solution and the tissues were incubated in the incubator for 3 hours.
After incubation, the tissues were washed with PBS to stop the MTT incubation.
The formazan that was metabolically produced by the tissues was extracted by overnight incubation of the tissues in isopropanol at room temperature or by incubation for at least 2 hours on a plate shaker. The optical density at a wavelength of 570 nm (OD570) of the extracts was spectrophotometrically determined. Blank values were established of 4 microtiter wells filled with isopropanol for each microtiter plate.

Negative controls validity:

valid

Positive controls validity:

valid

Remarks on result:

other: cell viability

Remarks:

10.4% cell viability were found following substance incubation in the EpiOcular test

The following results were obtained in the EpiOcular™ eye irritation assay:

The test substance is not able to directly reduce MTT.

The final mean viability of the tissues treated with the test substance was 10.4%.

Test substance identification		tissue 1	tissue 2	mean	Inter-tissue variability [%]
NC	mean OD570	1.651	1.614	1.632
	viability         [% of NC]	101.1	98.9	100.0	2.3
17/0010-1	mean OD570	0.156	0.182	0.169
	viability           [% of NC]	9.6	11.2	10.4	1.6
PC	mean OD570	0.325	0.438	0.382
	viability          [% of NC]	19.9	26.8	23.4	6.9

Interpretation of results:

Category 2 (irritating to eyes) based on GHS criteria

Conclusions:

Based on the results of the EpiOcular Test and by applying the evaluation criteria, it was concluded that 3-(1-Ethoxyethyl)-5-methyloxazolidin-2-on shows an eye irritation potential under the test conditions chosen.

Endpoint conclusion

Endpoint conclusion:

adverse effect observed (irritating)

Additional information

Skin corrosion/irritation tests in vitro:

The objective was to assess the skin irritation and corrosion potential of 3-(1-Ethoxyethyl)-5 -methyloxazolidin-2-on.

By using the currently available methods a single in vitro assay is not sufficient to cover the full range of skin irritating/corrosion potential. Therefore, two in vitro assays were part of this in vitro skin irritation and corrosion test strategy:

The Skin Corrosion Test (SCT) and Skin Irritation Test (SIT).

The potential of the test substance to cause dermal corrosion/irritation was assessed by a single topical application of 50 μL (corrosion test) or 30 μL (irritation test) of the undiluted test substance to a reconstructed three-dimensional human epidermis model (EpiDerm™). For the corrosion test, two EpiDerm™ tissues were incubated with the test substance for 3 minutes and 1 hour, each. The irritation test was performed with three EpiDerm™ tissues which were incubated with the test substance for 1 hour followed by a 42-hour post-incubation period.

Tissue destruction was determined by measuring the metabolic activity of the tissue after exposure/post-incubation by using a colorimetric test. The reduction of mitochondrial dehydrogenase activity measured by reduced formazan production after incubation with a tetrazolium salt (MTT) was chosen as endpoint. The formazan production of the epidermal tissues treated with the test substance is compared to that of negative control tissues. The quotient of the values indicates the relative tissue viability.

The following results were obtained in the EpiDerm™ skin corrosion/irritation test: The test substance is not able to directly reduce MTT.

Results of the Corrosion Test (SCT):

The mean viability of the tissues treated with the test substance determined after an exposure period of 3 minutes was 99.6% and it was 68.9% after an exposure period of 1 hour.

Results of the Irritation Test (SIT):

The mean viability of the tissues treated with the test substance determined after an exposure period of 1 hour with an about 42-hour post-incubation was 88.8%.

Based on the results observed and by applying the evaluation criteria, it was concluded that 3-(1-Ethoxyethyl)-5-methyloxazolidin-2-on does not show a skin irritation potential in the EpiDerm™ in vitro skin irritation and corrosion test strategy under the test conditions chosen.

Eye corrosion/irritation tests in vitro:

The objective was to assess the eye irritating potential of 3-(1-Ethoxyethyl)-5 -methyloxazolidin-2-on. By using the methods currently available a single in vitro assay is not sufficient to cover the full range of eye irritating potential. Therefore, two in vitro assays were part of this in vitro eye irritation test strategy: The Bovine Corneal Opacity and Permeability Test (BCOP Test) and EpiOcular Eye Irritation Test.

BCOP: The potential of 3-(1-Ethoxyethyl)-5-methyloxazolidin-2- on to cause

ocular irritation or serious damage to the eyes was assessed by a single topical application of 750 μL undiluted test substance to the epithelial surface of isolated bovine corneas.

Three corneas were treated with the test substance for 10 minutes followed by a 2-hour postincubation period.

In addition to the test substance, a negative control (NC; deionized water) and two positive controls (PC1 / PC2; 100% ethanol / 100% dimethylformamide) were applied to three corneas each.

Corneal opacity was quantitatively measured as the amount of light transmitted through the cornea. Permeability was quantitatively measured as the amount of sodium fluorescein dye that passes across the full thickness of the cornea. Both measurements were used to calculate an In Vitro Irritancy Score (IVIS) of the test substance. The mean IVIS score fot the test substance was 37.

EpiOcular: The potential of 3-(1-Ethoxyethyl)-5-methyloxazolidin-2-on

to cause ocular irritation was assessed by a single topical application of 50 μL of the undiluted test substance to a reconstructed three-dimensional, human cornea model (EpiOcular™).

Two EpiOcular™ tissues were incubated with the test substance for 30 minutes followed by a 2-hour post-incubation period. Tissue destruction was determined by measuring the metabolic activity of the tissue after exposure/post-incubation by using a colorimetric test. The reduction of mitochondrial dehydrogenase activity measured by reduced formazan production after incubation with a tetrazolium salt (MTT) was chosen as endpoint. The formazan production of the epidermal tissues treated with the test substance is compared to that of negative control tissues. The ratio of the values indicates the relative tissue viability. The following results were obtained in the EpiOcular™ eye irritation assay:

The test substance is not able to directly reduce MTT. The final mean viability of the tissues treated with the test substance was 10.4%.

Based on the results of the BCOP and EpiOcular Test and by applying the evaluation criteria, it was concluded that 3-(1-Ethoxyethyl)-5-methyloxazolidin-2-on shows an eye irritation potential in the in vitro eye irritation test strategy under the test conditions chosen.

Justification for classification or non-classification

Based on the results of the skin and eye irritation testing, the test item 3-(1-Ethoxyethyl)-5-methyloxazolidin-2-on is classified as eye irritating cat. 2 (H319) according to regulation (EC) No 1272/2008 (CLP).