Lithium trifluoromethanesulphonate

Skin irritation / corrosion

Administrative data

Endpoint:

skin corrosion: in vitro / ex vivo

Type of information:

experimental study

Adequacy of study:

key study

Study period:

From 31-August-2016 to 24-October-2016

Reliability:

1 (reliable without restriction)

Rationale for reliability incl. deficiencies:

guideline study

Remarks:

GLP compliant

Data source

Reference

Reference Type:

study report

Title:

Unnamed

Year:

2016

Report date:

2016

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:

Adopted 29 July 2016

Deviations:

no

Test guideline 2

Qualifier:

according to guideline

Guideline:

other: EU Method B.40 BIS (In Vitro Skin Corrosion: Human Skin Model Test)

Deviations:

no

GLP compliance:

yes (incl. QA statement)

Remarks:

Except for the Test Item characterisation which was conducted in an ISO 9000 environment.

Test material

Test material information

Constituent 1

Reference substance name:

Lithium trifluoromethanesulphonate

EC Number:

251-528-5

EC Name:

Lithium trifluoromethanesulphonate

Cas Number:

33454-82-9

Molecular formula:

CHF3O3S.Li

IUPAC Name:

lithium trifluoromethanesulphonate

Test material form:

solid: particulate/powder

Details on test material:

See confidential details on test material

Specific details on test material used for the study:

STABILITY AND STORAGE CONDITIONS OF TEST MATERIAL:
- At room temperature container flushed with nitrogen, desiccated

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:

Not applicable

Justification for test system used:

Recommended test system in international guidelines (OECD and EC).

Vehicle:

unchanged (no vehicle)

Details on test system:

RECONSTRUCTED HUMAN EPIDERMIS (RHE) TISSUE
- Model used: EpiDerm Skin Model EPI-200
- Tissue batch number(s): 24364 Kit M and L
- Source: MatTek Corporation, Ashland, MA, USA

TEMPERATURE USED FOR TEST SYSTEM
- Temperature used during treatment / exposure: All incubations, with the exception of the test item incubation of 3 minutes at room temperature, were carried out at 37.0 ± 1.0°C (actual range 35.6 - 37.3°C).

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 (37°C)
- Spectrophotometer: TECAN Infinite® M200 Pro Plate Reader
- Wavelength: 570nm

FUNCTIONAL MODEL CONDITIONS WITH REFERENCE TO HISTORICAL DATA
- Viability: OD (540-570) = 1.496+/-0.034 [1.0 - 3.0]
- Barrier function: ET-50 = 6.52 hrs [4.77 - 8.72 hrs]
- Morphology: Functional stratum corneum, viable basal cell layer, and intermediate spinous and granular layers
- Contamination: No contamination (absence of bacteria, fungus and mycoplasma)

NUMBER OF REPLICATE TISSUES: 4 tissues per test item together with a negative control and positive control (2 tissues were used for a 3-minute exposure to Lithium Trifluoromethanesulfonate and two for a 1-hour exposure)

NUMBER OF INDEPENDENT TEST SEQUENCES / EXPERIMENTS TO DERIVE FINAL PREDICTION: 1

PREDICTION MODEL / DECISION CRITERIA
- The test substance is considered to be corrosive to skin if the viability after 3 minutes exposure is less than 50%, or if the viability after 3 minutes exposure is greater than or equal to 50 % and the viability after 1 hour exposure is less than 15%.
- The test substance is considered to be non-corrosive to skin if the viability after 3 minutes exposure is greater than or equal to 50% and the viability after 1 hour exposure is greater than or equal to 15%.

Control samples:

yes, concurrent negative control

yes, concurrent positive control

Amount/concentration applied:

TEST MATERIAL
- Amount applied: 35.6 to 48.6 mg of the solid test item with 25 µl Milli-Q water (Millipore Corp., Bedford, Mass., USA) to ensure close contact of the test item to the tissue.

NEGATIVE CONTROL
- Amount applied: 50 µl Milli-Q water

POSITIVE CONTROL
- Amount applied: 50 µl KOH
- Concentration: 8N

Duration of treatment / exposure:

3-minute and 1-hour exposures

Number of replicates:

4 tissues per test item together with a negative control and positive control (2 tissues were used for a 3-minute exposure to Lithium Trifluoromethanesulfonate and two for a 1-hour exposure)

Results and discussion

In vitro

Results

Results 1

Irritation / corrosion parameter:

% tissue viability

Remarks:

Mean values

Run / experiment:

3-minute application

Value:

90

Vehicle controls validity:

not applicable

Negative controls validity:

valid

Remarks:

100%

Positive controls validity:

valid

Remarks:

11%

Remarks on result:

no indication of irritation

Results 2

Irritation / corrosion parameter:

% tissue viability

Remarks:

Mean values

Run / experiment:

1-hour application

Value:

63

Vehicle controls validity:

not applicable

Negative controls validity:

valid

Remarks:

100%

Positive controls validity:

valid

Remarks:

11%

Remarks on result:

no indication of irritation

Other effects / acceptance of results:

ACCEPTANCE OF RESULTS:
The absolute mean OD570 (optical density at 570 nm) of the negative control tissues 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-minute treatment: 1.324-2.615 / 1-hour treatment: 1.361-2.352).
The mean relative tissue viability following the 3-minute or 1-hour exposure to the positive control was 11%.

In the range 20-100% viability, the Coefficient of Variation (cut-off value <= 30%) between tissue replicates was <= 10% for the negative control and the 3-minute treatment with the test item, indicating that the test system functioned properly. For the 1-hour treatment with the test item the coefficient of variation was 69%, but because the individual results of the mean relative tissue were 30% and 97%, both above 15%, this does not affect the study outcome.

Any other information on results incl. tables

Preliminary tests

Lithium Trifluoromethanesulfonate was checked for colour interference in aqueous conditions and possible direct MTT reduction by adding the test item to MTT medium. Because the solutions did not turn blue/purple nor a blue/purple precipitate was observed it was concluded that Lithium Trifluoromethanesulfonate did not interfere with the MTT endpoint.

Main test

The mean absorption at 570 nm measured after treatment with Lithium Trifluoromethanesulfonate and controls are presented in the following Table. The individual OD570 measurements are presented in an other Table below.

Mean absorption in the in vitro skin corrosion test with Lithium Trifluoromethanesulfonate

	3 -minute application					1 -hour application
	A (OD570)	B (OD570)	Mean (OD570)		SD	A (OD570)	B (OD570)	Mean (OD570)		SD
Negative control	1.526	1.586	1.556	+/-	0.042	1.770	1.588	1.679	+/-	0.129
Lithium Trifluoromethanesulfonate	1.440	1.372	1.406	+/-	0.048	0.502	1.626	1.064	+/-	0.795
Positive control	0.180	0.155	0.167	+/-	0.018	0.205	0.163	0.184	+/-	0.030

SD= Standard deviation

Duplicate exposures are indicated by A and B

In this table the values are corrected for background absorption (0.0420). Isopropanol was used to measure the background absorption.

Individual OD measurements at 570 nm

	3-minute application (OD570) AB		1-hour application (OD570) AB
Negative control
OD570 measurement 1	1.5361	1.6025	1.7973	1.6268
OD570 measurement 2	1.5801	1.6369	1.8098	1.6275
OD570 measurement 3	1.5880	1.6449	1.8278	1.6348
Lithium Trifluoromethanesulfonate
OD570 measurement 1	1.5015	1.4262	0.5481	1.6941
OD570 measurement 2	1.4688	1.4062	0.5456	1.6541
OD570 measurement 3	1.4750	1.4106	0.5380	1.6556
Positive control
OD570 measurement 1	0.2226	0.2013	0.2484	0.2051
OD570 measurement 2	0.2199	0.1948	0.2513	0.2053
OD570 measurement 3	0.2221	0.1934	0.2425	0.2051

OD = Optical density

Duplicate exposures are indicated by A and B.

The following Table shows the mean tissue viability obtained after 3-minute and 1-hour treatments with Lithium Trifluoromethanesulfonate compared to the negative control tissues.

	3-minute application Viability, percentage of control	1 -hour application Viability, percentage of control
Negative control	100 (98 and 102) / SD: 3.8	100 (105 and 95) / SD: 10.3
Lithium Trifluoromethanesulfonate	90 (93 and 88) / SD: 4.7	63 (30 and 97) / SD: 69.1
Positive control	11 (12 and 10) / SD: 13.9	11 (12 and 10) / SD: 20.6

SD= Standard deviation

Skin corrosion is expressed as the remaining cell viability after exposure to the test item. The relative mean tissue viability obtained after the 3-minute and 1-hour treatments with Lithium Trifluoromethanesulfonate compared to the negative control tissues was 90% and 63% respectively. Because the mean relative tissue viability for Lithium Trifluoromethanesulfonate was not below 50% after 3 minutes treatment and not below 15% after 1 hour treatment, Lithium Trifluoromethanesulfonate is considered to be not corrosive.

Applicant's summary and conclusion

Interpretation of results:

GHS criteria not met

Conclusions:

Lithium Trifluoromethanesulfonate is not corrosive in the in vitro skin corrosion test (OECD Guideline No. 431, adopted 29 July 2016) under the experimental conditions described in this report.
The substance is not classified as corrosive to skin according to GHS criteria.

Executive summary:

The assessment of the corrosive potential to skin of Lithium Trifluoromethanesulfonate was carried out, under GLP compliance, using an in vitro skin corrosive test based on the guidelines described in: OECD No. 431 (adopted 29 July 2016) and EU Method B.40 BIS.

The test consisted of topical application of Lithium Trifluoromethanesulfonate (35.6 to 48.6 mg of the solid test item with 25 µl Milli-Q water) on the skin tissue for 3-minute and 1-hour. After exposure the skin tissue was thoroughly rinsed to remove the test item followed by immediate determination of the cytotoxic (corrosive) effect.

Cytotoxicity is expressed as the reduction of mitochondrial dehydrogenase activity measured by formazan production from 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyl tetrazolium bromide (MTT) at the end of the treatment.

The relative mean tissue viability obtained after the 3-minute and 1-hour treatments with Lithium Trifluoromethanesulfonate compared to the negative control tissues was 90% and 63% respectively.

Because the mean relative tissue viability for Lithium Trifluoromethanesulfonate was not below 50% after 3 minutes treatment and not below 15% after 1 hour treatment, Lithium Trifluoromethanesulfonate is considered to be non-corrosive in the performed experiment. The substance is not classified as corrosive to skin according to GHS criteria.