2-(cyclohexylamino)ethanesulphonic acid

Skin irritation / corrosion

Administrative data

Endpoint:

skin irritation: in vitro / ex vivo

Type of information:

experimental study

Adequacy of study:

key study

Study period:

2016-06-29 to 2016-07-01

Reliability:

1 (reliable without restriction)

Rationale for reliability incl. deficiencies:

guideline study

Data source

Reference

Reference Type:

study report

Title:

Unnamed

Year:

2017

Report date:

2017

Materials and methods

Test guideline

Test guideline 1

Qualifier:

according to guideline

Guideline:

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

Version / remarks:

28 July 2015

Deviations:

no

Test guideline 2

Qualifier:

according to guideline

Guideline:

EU Method B.46 (In Vitro Skin Irritation: Reconstructed Human Epidermis Model Test)

Version / remarks:

06 July 2012

Deviations:

no

GLP compliance:

yes (incl. QA statement)

Test material

Test material information

Constituent 1

Reference substance name:

2-(cyclohexylamino)ethanesulphonic acid

EC Number:

203-115-6

EC Name:

2-(cyclohexylamino)ethanesulphonic acid

Cas Number:

103-47-9

Molecular formula:

C8H17NO3S

IUPAC Name:

2-(cyclohexylamino)ethanesulphonic acid

Test material form:

solid: particulate/powder

In vitro test system

Test system:

human skin model

Source species:

human

Cell type:

non-transformed keratinocytes

Cell source:

other: adult donors, not further specified

Details on animal used as source of test system:

Not applicable

Justification for test system used:

The EPISKIN model has been validated for irritation testing in an international trial. After a review of scientific reports and peer reviewed publications on the EPISKIN method, it showed evidence of being a reliable and relevant stand-alone test for predicting rabbit skin irritation, when the endpoint is evaluated by MTT reduction and for being used as a replacement for the Draize Skin Irritation test (OECD TG 404 and Method B.4 of Annex V to Directive 67/548/EEC) for the purposes of distinguishing between skin irritating and no- skin irritating test substances (STATEMENT OF VALIDITY OF IN-VITRO TESTS FOR SKIN IRRITATION; ECVAM; Institute for Health & Consumer Protection; Joint Research Centre; European Commission; Ispra; 27 April 2007).

Vehicle:

unchanged (no vehicle)

Details on test system:

RECONSTRUCTED HUMAN EPIDERMIS (RHE) TISSUE
- Model used: EpiSkinTM Small Model (EpiSkinTMSM) (from EPISKIN SNC Lyon, France)
- Tissue batch number: 16-EKIN-026
- Production date: not provided
- Expiry date: 04 July 2016
- Certification date: 28 June 2016
- Shipping date: not provided
- Delivery date: not provided
- Date of initiation of testing: 29 June 2016

TEMPERATURE USED FOR TEST SYSTEM
- Temperature used during treatment / exposure: room temperature
- Temperature of post-treatment incubation: 37 °C in an incubator with 5 % CO2, ≥95 % humidified atmosphere

REMOVAL OF TEST MATERIAL AND CONTROLS
-Volume and number of washing steps: 1 washing with approximately 25 mL PBS 1x solution
- Observable damage in the tissue due to washing: none
- Modifications to validated SOP: no

MTT DYE USED TO MEASURE TISSUE VIABILITY AFTER TREATMENT / EXPOSURE
- MTT concentration: 0.3 mg/mL MTT
- Incubation time: 3 hours (± 5 min)
- Spectrophotometer: 96-well plate spectrophotometer
- Wavelength: 570 nm
- Filter: not specified
- Filter bandwidth: not specified
- Linear OD range of spectrophotometer: not specified

FUNCTIONAL MODEL CONDITIONS WITH REFERENCE TO HISTORICAL DATA
Qualitiy control was performed at manufacturer for batch and showed historical scoring (22.7 -/+ 0.5) and IC50 (2.6 mg/mL) determinations in the expected ranges (>= 19.5 and >= 1.5- <=3 mg/mL respectively).
- Contamination: Blood and epidermal samples from same donors were free of HIV1+2 antibodies, hepatitis C antibodies, hepatitis B antigen HBs, bactieria, fungus and mycoplasma

NUMBER OF REPLICATE TISSUES: 3

CONTROL TISSUES USED IN CASE OF MTT DIRECT INTERFERENCE
Not needed as no colour change was observed after three hours of incubation.

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

PREDICTION MODEL / DECISION CRITERIA
The test chemical is identified as requiring classification and labelling according to UN GHS (Category 2 or Category 1), if the mean relative viability after 15 minutes exposure and 42 hours post incubation is less or equal (≤) to 50 % of the negative control. If the viability is > 50 % the test item is non-corrosive.

Control samples:

yes, concurrent negative control

yes, concurrent positive control

Amount/concentration applied:

TEST MATERIAL
- Amount applied: 10 mg (to moistened skin)

NEGATIVE CONTROL
- Amount applied: 10 µL
- Concentration: 1x

POSITIVE CONTROL
- Amount applied: 10 µL
- Concentration: 5 % aq.

Duration of treatment / exposure:

15 minutes

Duration of post-treatment incubation (if applicable):

42 hours

Number of replicates:

3

Results and discussion

In vitro

Results

Irritation / corrosion parameter:

% tissue viability

Run / experiment:

mean

Value:

104

Vehicle controls validity:

not applicable

Negative controls validity:

valid

Remarks:

100

Positive controls validity:

valid

Remarks:

18

Remarks on result:

no indication of irritation

Other effects / acceptance of results:

- OTHER EFFECTS:
- Visible damage on test system: none
- Direct-MTT reduction: No colour change was observed after three hours of incubation. The test material did not interact with the MTT, therefore additional controls and data calculations were not necessary. A false estimation of viability can be precluded.
- Colour interference with MTT: The test item showed no ability to become coloured in contact with water. The intrinsic colour of test item is white and therefore considered to be not able to significantly stain the tissues and lead false estimate of viability. Furthermore, the test item was completely removed from the epidermal surface at rinsing period. Additional controls and data calculations were not necessary. A false estimation of viability can be precluded.

DEMONSTRATION OF TECHNICAL PROFICIENCY: Prior to routine use of the method the laboratory demonstrated the technical proficiency in a separate study using the ten Proficiency Chemicals according to OECD Test Guideline No. 439.

ACCEPTANCE OF RESULTS:
- Acceptance criteria met for negative control: YES (mean OD of 0.762 in the range from 0.6 to 1.5; SD of 10.23 therefore < 18)
- Acceptance criteria met for positive control: YES (mean viability of 18 % in the range from 0 to 40 %; SD of 7.55 therefore < 18)
- Acceptance criteria met for variability between replicate measurements: YES (test substance: SD of 14.82 therefore < 18)
- Range of historical values if different from the ones specified in the test guideline: NC: OD mean 0.802 (min 0.555, max. 1.32); PC: OD mean 0.1 (min 0.015, max. 0.299), Viability mean 13 % (min. 2 %, max. 39 %)

Any other information on results incl. tables

Table 1: Results

Substance		Optical Density (OD)	Viability (%)
Negative Control: 1x PBS	1	0.672	88
	2	0.798	105
	3	0.815	107
	mean	0.762	100
	standard deviation (SD)		10.23
Positive Control: SDS (5 % aq.)	1	0.077	10
	2	0.151	20
	3	0.190	25
	mean	0.139	18
	standard deviation (SD)		7.55
Test item	1	0.773	102
	2	0.691	91
	3	0.914	120
	mean	0.793	104
	standard deviation (SD)		14.82

Applicant's summary and conclusion

Interpretation of results:

GHS criteria not met

Conclusions:

The results obtained using the EPISKIN model showed that the test item reveals no skin irritation potential.

Executive summary:

An EpiSkinTM SM test with the test item was performed to predict its irritation potential by measurement of its cytotoxic effect, as reflected in the MTT assay, according to the OECD Test Guideline No. 439, 28 July 2015.

Triplicates of the human skin model EPISKIN (Reconstructed Human Epidermis, SkinEthic Laboratories) were treated with test item and incubated for 15 minutes at room temperature. Exposure of the reconstructed human epidermis skin units with test item was terminated by rinsing with PBS 1x solution. Epidermis units were then incubated at 37 °C for 42 hours in an incubator with 5 % CO2. The viability of each disk was assessed by incubating the tissues for 3 hours with MTT solution at 37 °C in 5 % CO2 protected from light. The precipitated formazan was then extracted using acidified isopropanol and quantified spectrophotometrically.

SDS (5 % aq.) and 1×PBS treated epidermis (three units / positive and negative control) were used as positive and negative controls respectively. For each treated tissue viability was expressed as a percentage relative to negative control.

In this in vitro skin irritation test using the EPISKIN model, the test item did not show significantly reduced cell viability in comparison to the negative control (mean value: 104 %). All obtained test item viability results were far above 50 % when compared to the viability values obtained from the negative control. Therefore the test item was considered to be non-irritant to skin.

Positive and negative controls showed the expected cell viability values within acceptable limits. The experiment was considered to be valid.

The results obtained from this in vitro skin irritation test, using the EPISKIN model, indicated that the test item reveals no skin irritation potential under the utilised testing conditions.