1-[(2-hydroxyethyl)thio]propan-2-ol

Endpoint summary

Description of key information

The in vitro skin corrosion of the test substance was determined in accordance with the OECD Guideline for Testing of Chemicals 431. The Relative mean tissue viability calculated as a percentage of the negative control was 86.9% after the 60 minutes exposure and 78.5% after the 3 minutes exposure. The test item did not meet the criteria for classification as corrosive to the skin according to the criteria laid down in the OECD Guideline for Testing of Chemicals 431.

 

The in vitro skin irritation of the test substance was determined in accordance with the OECD Guideline for Testing of Chemicals 439. The percentage of viability obtained with the test item 1-[(2-hydroxyethyl)thio]propan-2-ol was 80.735%, therefore it has to be considered as non-irritant to the skin according to the criteria laid down in the OECD Guideline for Testing of Chemicals 439. All the acceptance criteria were met and the study is therefore considered as valid.

 

The in vitro skin irritation of the test substance was determined in accordance with the OECD Guideline for Testing of Chemicals 437. An In Vitro Irritation Score (IVIS) of 18.69 was calculated for 1-[(2-hydroxyethyl)thio]propan-2-ol from corneal opacity and permeability measurements. No prediction can be made if the IVIS is >3 but ≤ 55 and, therefore no conclusion can be made based on the criteria laid down in the OECD Guideline for Testing of Chemicals 437. All the acceptance criteria were met and the study is therefore considered as valid.

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

Study period:

From 8 May 2017 to 28 June 2017

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

Source species:

other: reconstructed human epidermis

Details on animal used as source of test system:

Not applicable

Vehicle:

unchanged (no vehicle)

Details on test system:

RECONSTRUCTED HUMAN EPIDERMIS (RHE) TISSUE
- Model used: MatTek’s EpiDermTM model
- Tissue batch number(s): Lot# 25816
- Date of initiation of testing: 08 May 17

TEMPERATURE USED FOR TEST SYSTEM
- Temperature used during treatment / exposure: 37°C

DYE BINDING METHOD
- Dye used in the dye-binding assay: MTT
- Spectrophotometer: BMG LabTech FluoStar Optima
- Wavelength: 570 nm
- Filter: None

Control samples:

yes, concurrent negative control

yes, concurrent positive control

Amount/concentration applied:

TEST MATERIAL
- Amount(s) applied (volume or weight with unit): 50 μl

NEGATIVE CONTROL
- Amount(s) applied (volume or weight): 50 μl

POSITIVE CONTROL
- Amount(s) applied (volume or weight): 50 μl

Duration of treatment / exposure:

3 and 60 minutes

Number of replicates:

Triplicate

Irritation / corrosion parameter:

% tissue viability

Run / experiment:

3 minutes (mean)

Value:

78.5

Vehicle controls validity:

not applicable

Negative controls validity:

valid

Positive controls validity:

valid

Irritation / corrosion parameter:

% tissue viability

Run / experiment:

60 minutes (mean)

Value:

86.9

Vehicle controls validity:

not applicable

Negative controls validity:

valid

Positive controls validity:

valid

Interpretation of results:

GHS criteria not met

Conclusions:

The Relative mean tissue viability calculated as a percentage of the negative control was 86.9% after the 60 minutes exposure and 78.5% after the 3 minutes exposure. The test item did not meet the criteria for classification as corrosive to the skin according to Regulation (EC) No.1272/2008 on the Classification, Labelling and Packaging of Substances and Mixtures.

Executive summary:

The in vitro skin corrosion of the test substance was determined in accordance with the OECD Guideline for Testing of Chemicals 431. The purpose of this test is to evaluate the corrosivity potential of the test item using the EpiDerm™ Reconstituted Human Epidermis after treatment periods of 3 and 60 minutes. Corrosion is directly related to cytotoxicity in the EpiDerm™ tissue. Cytotoxicity is determined by the reduction of MTT to formazan by viable cells in the test item treated tissues relative to the corresponding negative control. The results are used to make a prediction of the corrosivity potential of the test item.

Prior to the testing, the test substance was checked for interference with water and/or MTT. No interference was identified.

Triplicate tissues were treated with the test item for exposure periods of 3 and 60 minutes. A MTT assay was performed in order to measure the test viability following the exposure to the test substance. The optical density was measured at 570 nm to determine the concentration of formazan produced by the viable cells from the reduction of MTT. Data are presented in the form of percentage viability (MTT reduction in the test item treated tissues relative to negative control tissues).

The Relative mean tissue viability calculated as a percentage of the negative control was 86.9% after the 60 minutes exposure and 78.5% after the 3 minutes exposure. The test item did not meet the criteria for classification as corrosive to the skin according to Regulation (EC) No.1272/2008 on the Classification, Labelling and Packaging of Substances and Mixtures.

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)

Version / remarks:

Adopted: 28 July 2015

Deviations:

no

GLP compliance:

yes (incl. QA statement)

Test system:

human skin model

Vehicle:

unchanged (no vehicle)

Details on test system:

RECONSTRUCTED HUMAN EPIDERMIS (RHE) TISSUE
- Model used: EpiDermTM (EPI-200) Reconstituted Human Epidermis
- Tissue batch number(s): Lot# 25834
- Date of initiation of testing: 11 JUL 17

TEMPERATURE USED FOR TEST SYSTEM
- Temperature used during treatment / exposure: 37°C

NUMBER OF REPLICATE TISSUES:
Triplicate

Control samples:

yes, concurrent negative control

yes, concurrent positive control

Amount/concentration applied:

TEST MATERIAL
- Amount(s) applied (volume or weight with unit): 30 μl of neat test item

NEGATIVE CONTROL
- Amount(s) applied (volume or weight): 30 μl of neat Sterile Dulbecco’s Phosphate Buffered Saline (DPBS)

POSITIVE CONTROL
- Amount(s) applied (volume or weight): 30 μl of
- Concentration (if solution): SDS 5%
- Solvent: water

Duration of treatment / exposure:

60 minutes (25 minutes at room temperature and 35 minutes at 37°C, 5% CO2), followed by 42 hours’ post-treatment incubation, prior to the MTT endpoint

Duration of post-treatment incubation (if applicable):

42 hours’ post-treatment incubation

Number of replicates:

Triplicate

Irritation / corrosion parameter:

% tissue viability

Run / experiment:

Mean value

Value:

80.735

Vehicle controls validity:

not applicable

Negative controls validity:

valid

Positive controls validity:

valid

Interpretation of results:

GHS criteria not met

Conclusions:

The test item did not reduce the viability to 50% or below and should be considered as non-irritant to the skin.

Executive summary:

The in vitro skin irritation of the test substance was determined in accordance with the OECD Guideline for Testing of Chemicals 439. This in vitro risk assessment assay predicts the Skin irritation potential of a chemical by measurement of its cytotoxic effect on the EpiDerm™ tissue model.

Prior to the testing, the test substance was checked for interference with water and/or MTT. No interference was identified.

Skin irritation of the test substance and controls was evaluated in triplicate. After 60 minutes’ exposure on the surface of the EpiDerm™ reconstructed human epidermis and a 42h post-exposure incubation time, viability of the tissues was assessed and compared to the negative control.

The percentage of viability obtained with the test item 1-[(2-hydroxyethyl)thio]propan-2-ol was 80.735%, therefore it has to be considered as non-irritant to the skin according to the criteria laid down in the OECD Guideline for Testing of Chemicals 439. All the acceptance criteria were met and the study is therefore considered as valid.

The test item did not meet the criteria for classification as irritant to the skin according to Regulation (EC) No.1272/2008 on the Classification, Labelling and Packaging of Substances and Mixtures.

Endpoint conclusion

Endpoint conclusion:

no adverse effect observed (not irritating)

Eye irritation

Link to relevant study records

Reference

Endpoint:

eye irritation: in vitro / ex vivo

Type of information:

experimental study

Adequacy of study:

key study

Study period:

From August 03, 2017 to September 08, 2017

Reliability:

1 (reliable without restriction)

Rationale for reliability incl. deficiencies:

guideline study

Remarks:

Assay was conducted by a GLP accredited laboratory using OECD Guideline 437

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:

yes

Remarks:

The end time for the 2-hour incubation period was not recorded in the raw data

Principles of method if other than guideline:

The end time for the 2-hour incubation period was not recorded in the raw data. However, the subsequent procedure was noted as completed 2 hours and 10 minutes after the start of the incubation period. This deviation from protocol was believed not to have affected the integrity or outcome of the study as the negative and positive controls gave satisfactory results. In addition, the study was considered to be GLP-compliant but the expiry date for the test article stability was not based on known stability data.

GLP compliance:

yes (incl. QA statement)

Species:

cattle

Strain:

not specified

Details on test animals or tissues and environmental conditions:

Corneas from bovine eyes were obtained from a local abattoir. The eyes were removed after slaughter, completely immersed in Hanks’ Balanced Salt Solution (containing penicillin at 100 IU/mL and streptomycin at 100 µg/mL) in a suitably sized container and transported on the same day to the testing facility. On arrival at the test facility the eyes were carefully examined for defects including increased opacity, scratches and neovascularisation. Only corneas free from such defects were used

Vehicle:

unchanged (no vehicle)

Controls:

yes, concurrent positive control

yes, concurrent negative control

Amount / concentration applied:

A volume of 750 µL of the test article was applied to each of three corneas followed by a ten minute incubation at 32 °C. The test article was administered without dilution. A volume of 750 µL of the negative or positive control was similarly applied to further groups of three corneas

Duration of treatment / exposure:

Ten minute incubation period

Duration of post- treatment incubation (in vitro):

Corneas were incubated (horizontally) for approximately 2 hours prior to the measurement of corneal opacity. For the permeability endpoint (optical density), corneas were incubated in the vertical position for 1 hour and 25 minutes. The negative and positive control groups were subject to the same procedures

Number of animals or in vitro replicates:

Three corneas (triplicate)

Details on study design:

SELECTION AND PREPARATION OF CORNEAS
All eyes were carefully examined for defects on arrival, including increased opacity, scratches and neovascularisation. Only corneas free from such defects were used. The selected corneas were excised from the eyes and loaded onto a holder that contained chambers (posterior and anterior) filled with pre-warmed Minimal Essential Medium (MEM). To avoid bubbles forming, the posterior chamber was filled first. The holders were incubated at 32 ± 1 °C for at least 1 hour. After this point, the media in both chambers was exchanged for fresh MEM in the order of posterior chamber followed by anterior chamber, therein ensuring that the corneas retained their natural curvature

QUALITY CHECK OF THE ISOLATED CORNEAS
Following preparation in the MEM, the opacity of each cornea was measured using an opacitometer. Any corneas found to have scratches or increased neovascularization or an opacity of >7 opacity units when examined prior to treatment were discarded

NUMBER OF REPLICATES
Three (triplicate)

NEGATIVE CONTROL USED
Yes, the negative control substance was 0.9% sodium chloride solution

POSITIVE CONTROL USED
Yes, the positive control substance was dimethylformamide (DMF)

APPLICATION DOSE AND EXPOSURE TIME
The test article was not diluted prior to administration. A volume of 750 µL of the test article was applied to each of three corneas followed by a 10 minute incubation at 32 °C

POST-INCUBATION PERIOD: Yes

REMOVAL OF TEST SUBSTANCE
After the 10 minute incubation period, the corneas were individually washed with media containing phenol red (as a pH indicator) until this indicator showed no pH effect occurring and demonstrating that the test article had been removed successfully. The corneas were then washed once in media without phenol red

POST-EXPOSURE INCUBATION
Yes. After washing, the anterior chamber was filled with fresh MEM and the corneas were incubated (horizontally) for approximately 2 hours. Corneal opacity was subsequently measured and then the anterior chamber emptied. For the permeability endpoint, 1 mL of sodium fluorescein (4 mg/mL solution) was added into the anterior chamber and the corneas were incubated in the vertical position for 1 hour and 25 minutes. Following this period, the media in the posterior chamber was removed and held in a labelled tube for later analysis

METHODS FOR MEASURED ENDPOINTS
- Corneal opacity: Opacitometer
- Corneal permeability: Passage of sodium fluorescein dye measured with the aid of spectrophotometry (OD490)
- Others: It was apparent from visual observation that the corneas treated with the test article appeared cloudy post treatment and the corneas treated with the positive control were cloudy and wrinkled following treatment

SCORING SYSTEM: In Vitro Irritancy Score (IVIS)

DECISION CRITERIA
The test article is concluded as inducing serious eye damage if the IVIS is >55 or as not requiring classification for eye irritation if the IVIS is ≤3. No prediction can be made if the IVIS is >3 but ≤55

Irritation parameter:

in vitro irritation score

Remarks:

Mean corrected

Value:

18.69

Vehicle controls validity:

not applicable

Negative controls validity:

valid

Positive controls validity:

valid

Other effects / acceptance of results:

OTHER EFFECTS:
- Visible damage on test system: The corneas treated with 1-[(2-hydroxyethyl)thio]propan-2-ol appeared cloudy post-treatment and the corneas treated with the positive control were noted to be cloudy and wrinkled following treatment

ACCEPTANCE OF RESULTS:
- Acceptance criteria met for negative control: yes, the negative control yielded opacity and permeability values that were less than the established upper limits for the endpoints for bovine corneas as treated at the testing facility
- Acceptance criteria met for positive control: yes, the positive control yielded an IVIS within 2 standard deviations of the historical control mean

Corneal Opacity

Test Substance	Cornea Number	Initial Opacity	Post Incubation Opacity	Change in Opacity	Mean Change in Opacity	Corrected Opacity	Mean Corrected Opacity
Negative	23	0	-1	-1	-0.67	-0.3	0
Negative	24	0	-1	-1		-0.3
Negative	25	0	0	0		0.7
Test article	18	0	16	16	N/A	16.7	16
Test article	19	0	15	15		15.7
Test article	20	0	15	15		15.7
Positive	14	-1	60	61	N/A	61.7	62.7
Positive	15	-1	69	70		70.7
Positive	16	-2	53	55		55.7

Corneal Permeability (Density)

Test Substance	Cornea Number	Mean Blank OD490	OD490	Corrected OD490	Mean Corrected OD490	Final Corrected OD490	Mean Group Corrected OD490
Negative	23	0.04	0.041	0.001	0.002	0	0
Negative	24		0.042	0.003		0.001
Negative	25		0.04	0.001		-0.001
Test article	18		0.423	0.383	N/A	0.381	0.18
Test article	19		0.173	0.133		0.132
Test article	20		0.067	0.027		0.026
Positive	14		0.416	0.376	N/A	0.375	0.243
Positive	15		0.13	0.091		0.089
Positive	16		0.307	0.276		0.266

Calculated IVIS

Test Chemical	Mean Opacity	Mean Permeability	IVIS (Mean Opacity + (15 x Mean Permeability))
Test article	16	0.18	18.69
Negative control	0	0	0
Positive control	62.7	0.243	66.31

N/A Not applicable.

The data in these tables was computer generated. In this system individual and derived figures are rounded. Thereby recalculation of derived values from the individual data will, in some instances, yield minor variations

Interpretation of results:

other: inconclusive

Conclusions:

The results of this in vitro Bovine Corneal Opacity and Permeability (BCOP) assay suggests that a conclusive prediction cannot be made on the eye irritation potential, or for the hazard classification, of 1-[(2-hydroxyethyl)thio]propan-2-ol as the IVIS was >3 but < 55.1 (IVIS = 18.69).

Executive summary:

An in vitro Bovine Corneal Opacity and Permeability (BCOP) assay was performed in line with OECD Guideline 437 (Bovine Corneal Opacity and Permeability Test Method).

The undiluted test material was applied to three cattle corneas obtained from an abattoir at a volume of 750 µL, after which each cornea was incubated at 32 ± 1 °C for 10 minutes and then washed with phenol red-containing media followed by a media without phenol red. Corneal opacity was measured after a 2 hour period of horizontal incubation. For permeability, the corneas were incubated in the vertical position for 1 hour and 25 minutes at 32 ± 1°C within a sodium fluorescein solution. Thereafter, three 350 μL aliquots of this media (per cornea) were analysed for optical density at 490 nanometers (OD490). A positive (dimethylformamide) and negative (0.9% sodium chloride solution) control was applied using the same procedure to additional groups of corneas.

The mean corrected opacity reading for the test article, positive control, and negative control was 16.0, 62.7, and 0.0, respectively. The mean group corrected optical density for the test article was 0.180 and the mean group corrected optical density for the positive and negative control was 0.243 and 0.000, respectively. An In Vitro Irritation Score (IVIS) of 18.69 was calculated for 1-[(2-hydroxyethyl)thio]propan-2-ol from corneal opacity and permeability measurements. No prediction can be made if the IVIS is >3 but ≤ 55 and, therefore, the study is inconclusive.

Endpoint conclusion

Endpoint conclusion:

adverse effect observed (irritating)

Respiratory irritation

Endpoint conclusion

Endpoint conclusion:

no study available

Justification for classification or non-classification

GLP-compliant studies were performed in order to investigate the skin corrosion and skin irritation of 1-[(2-hydroxyethyl)thio]propan-2-ol in accordance with the OECD Testing Guidelines 431 and 439 respectively. All acceptance criteria were met and these studies are therefore considered as valid. The substance did not meet the criteria for classification as corrosive or irritant to the skin according to Regulation (EC) N° 1272/2008.

 

A GLP-compliant study was performed in order to investigate the eye irritation of 1-[(2-hydroxyethyl)thio]propan-2-ol in accordance with the OECD Testing Guideline 437 (BCOP). All acceptance criteria were met and this study is therefore considered as valid. The study did not allow to conclude regarding the capacity of the substance to induce eye irritation.

According to ECHA Guidance on Information Requirements and Chemical Safety Assessment Chapter R.7a: Endpoint specific guidance (Version 6.0 - July 2017), the BCOP possesses a good predictivity to identify substances inducing serious eye damage and therefore meeting the criteria for classification as Eye Dam. 1 according to Regulation (EC) N° 1272/2008. Since 1-[(2-hydroxyethyl)thio]propan-2-ol was not identified during the study as inducing serious eye damage, it can be concluded that the substance does not meet the criteria for classification as Eye Dam. 1 according to Regulation (EC) N° 1272/2008. Therefore it is proposed to classify 1-[(2-hydroxyethyl)thio]propan-2-ol as Eye Irrit 2 without performing additional in vitro eye irritation testing as it represents a worst-case scenario.