4-(cyclohexylamino)butane-1-sulfonic acid

Endpoint summary

Description of key information

A DEREK prediction on the skin sensitizing potential of 4 -(cyclohexylamino)butane-1 -sulfonic acid was negative and predicted the substance to be a non sensitizer.

 

4 -(cyclohexylamino)butane-1 -sulfonic acid did not react with cysteine and lysine containing peptides resulting in a negative outcome for the DPRA.

 

The KeratinoSens^TM assay did not show a biologically relevant activation of the antioxidant/electrophile responsive element (ARE)-dependent pathway when exposed to the substance and was therefore concluded to be negative.

 

Key value for chemical safety assessment

Skin sensitisation

Link to relevant study records

Reference

Reference 1

Endpoint:

skin sensitisation, other

Remarks:

In silico assessment

Type of information:

(Q)SAR

Adequacy of study:

weight of evidence

Study period:

1 May 2019

Reliability:

2 (reliable with restrictions)

Rationale for reliability incl. deficiencies:

results derived from a valid (Q)SAR model and falling into its applicability domain, with adequate and reliable documentation / justification

Justification for type of information:

An in silico assessment is mentioned in the ECHA guidance as one of the non-animal tests that may be performed as part of a weight of evidence approach for the endpoint skin sensitization.

Qualifier:

no guideline required

Principles of method if other than guideline:

An in silico assessment was performed with DEREK NEXUS version 6.0.1.

GLP compliance:

no

Justification for non-LLNA method:

Since 11 October 2016 it is legally required to consider all available information for the endpoint skin sensitisation and to use a non in vivo test strategy based on in chemico, in silico and in vitro skin tests combined in a weight-of-evidence approach. An in vivo test (LLNA) is only allowed as last resort. DEREK results are adequate to be used in a weight-of-evidence approach together with in chemico/in vitro studies to complete the endpoint skin sensitisation.

Key result

Group:

test chemical

Run / experiment:

other: 4-(cyclohexylamino)butane-1-sulfonic acid

Parameter:

other: Prediction on skin sensitization

Remarks on result:

no indication of skin sensitisation

Other effects / acceptance of results:

4-(cyclohexylamino)Butane-1-sulfonic acid does not contain any unclassified or misclassified features and is consequently predicted to be a non-sensitizer. (see prediction in study report)

Interpretation of results:

other: study is part of a weight of evidence approach and is not used for classification on its own

Conclusions:

4-(cyclohexylamino)butane-1-sulfonic acid is predicted to be not sensitizing to the skin.

Executive summary:

DEREK NEXUS version 6.0.1 did not yield any alerts for skin sensitization for the test item. Additionally, 4-(cyclohexylamino)butane-1-sulfonic acid does not contain any unclassified or misclassified features and is consequently predicted to be a non-sensitizer.

Reference 2

Endpoint:

skin sensitisation: in chemico

Type of information:

experimental study

Adequacy of study:

weight of evidence

Study period:

25 March 2019 - 26 March 2019

Reliability:

1 (reliable without restriction)

Rationale for reliability incl. deficiencies:

guideline study

Justification for type of information:

The validated in chemico skin sensitization test is the DPRA assay, which is recommended in international guidelines (e.g. OECD) and mentioned in the ECHA guidance as the in chemico test to be performed as part of weight of evidence.

Qualifier:

according to guideline

Guideline:

OECD Guideline 442C (In Chemico Skin Sensitisation: Direct Peptide Reactivity Assay (DPRA))

Version / remarks:

4 February 2015

Deviations:

no

GLP compliance:

yes (incl. QA statement)

Type of study:

direct peptide reactivity assay (DPRA)

Justification for non-LLNA method:

A validated in chemico skin sensitization test is the DPRA assay, which is recommended in international guidelines (e.g. OECD) and mentioned in the ECHA guidance as one of the non-animal tests to be performed as part of weight of evidence.

Details of test system:

cysteine peptide, (Ac-RFAACAA-COOH)

lysine peptide (Ac-RFAAKAACOOH)

Details on the study design:

TEST ITEM PREPARATION
Solubility of the test item in an appropriate solvent was assessed before performing the DPRA. An appropriate solvent dissolved the test item completely, i.e. by visual inspection the solution had to be not cloudy nor have noticeable precipitate. The following solvents were evaluated: acetonitrile (ACN) and Milli-Q water (MQ). Test item stock solutions were prepared freshly for each reactivity assay.
For both the cysteine and lysine reactivity assay 35.90 mg of test item was pre-weighed into a clean amber glass vial and dissolved, just before use, in 1525 μL MQ after vortex mixing to obtain a 100 mM solution. Visual inspection of the forming of a clear solution was considered sufficient to ascertain that the test item was dissolved. The test item, positive control and peptide samples were prepared less than 4 hours before starting the incubation of the cysteine (cys) or lysine (lys) reactivity assay, respectively.

TEST SYSTEM
Synthetic peptides containing cysteine (SPCC) (Ac-RFAACAA-COOH) or synthetic peptides containing lysine (SPCL) (Ac-RFAAKAA-COOH). The molecular weight is 750.9 g/mol for SPCC and 775.9 g/mol for SPCL. Rationale: Recommended test system in the international OECD guideline for DPRA studies.
Source: JPT Peptide Technologies GmbH, Berlin, Germany.
Storage: The peptides were stored in the freezer (≤-15°C) for a maximum of 6 months.
Incubation:The samples (reference controls, calibration solutions, co-elution control, positive controls and test item samples) were placed in the autosampler in the dark and incubated at 25±2.5°C. The incubation time between placement of the samples in the autosampler and analysis of the first RCcysB- or RClysB-sample was 23.4 hours. The time between the first RCcysB- or RClysB-injection and the last injection of a cysteine or lysine sequence, respectively, did not exceed 30 hours.
Analysis: All samples were analyzed according to the HPLC method presented in Table 1. (See 'other information on materials and methods').
The HPLC sequences of the cysteine and lysine reactivity assay for the test item are presented in Table 2. (See 'other information on materials and methods').

POSITIVE CONTROL
Cinnamic aldehyde
- Purity: 99.1%
- Expiry of batch: 30 November 2021


DATA EVALUATION
The concentration of SPCC or SPCL was spectrophotometrically determined at 220 nm in each sample by measuring the peak area of the appropriate peaks by peak integration and by calculating the concentration of peptide using the linear calibration curve derived from the standards. The Percent Peptide Depletion was determined in each sample by measuring the peak area and dividing it by the mean peak area of the relevant reference controls C according to the following formula: Percent Peptide Depletion= [1-(Peptide Peak Area in Replicate Injection (at 220 nm)/Mean Peptide Peak Area in Reference Controls (at 220 nm))]x100

In addition, the absorbance at 258 nm was determined in each sample by measuring the peak area of the appropriate peaks by peak integration. The ratio of the 220 nm peak area and the 258 nm peak was used as an indicator of co-elution. For each sample, a ratio in the range of 90%
DATA INTERPRETATION
The mean Percent Cysteine Depletion and Percent Lysine Depletion were calculated for the test item. Negative depletion was considered as “0” when calculating the mean. By using the Cysteine 1:10 / Lysine 1:50 prediction model (see Table 3), the threshold of 6.38% average peptide depletion was used to support the discrimination between a skin sensitizer and a non-sensitizer.

Positive control:

cinnamic aldehyde

Key result

Group:

test chemical

Run / experiment:

run/experiment 1

Parameter:

mean cystein depletion

Value:

0 %

At concentration:

100 mM

Vehicle controls validity:

not applicable

Negative controls validity:

valid

Remarks:

CV between reference controls: 0.9%

Positive controls validity:

valid

Remarks:

Mean percentage SPCC: 73.5%

Remarks on result:

other: SD: 0%

Key result

Group:

test chemical

Run / experiment:

run/experiment 1

Parameter:

mean lysine depletion

Value:

1.5 %

At concentration:

100 mM

Vehicle controls validity:

not applicable

Negative controls validity:

valid

Remarks:

CV between reference controls: 3.2%

Positive controls validity:

valid

Remarks:

Mean percentage SPCL: 68.3%

Remarks on result:

other: SD: 2.6%

Outcome of the prediction model:

no or minimal reactivity [in chemico]

Other effects / acceptance of results:

Upon preparation as well as after incubation of the SPCC and SPCL test item samples, no precipitate or phase separation was observed in any of the samples.
No co-elution occurred during both assays.
See Table 4 & 5 "any other information on results incl. tables" for acceptability criteria.

Table 4 Acceptability of the Direct Peptide Reactivity Assay (DPRA)

	Cysteine reactivity assay		Lysine reactivity assay
	Acceptability criteria	Results for SPCC	Acceptability criteria	Results for SPCL
Correlation coefficient (r^2) standard calibration curve	>0.99	0.9998	>0.99	0.9998
Mean peptide concentration RC-A samples (mM)	0.50 ± 0.05	0.493 ± 0.002	0.50 ± 0.05	0.493 ± 0.004
Mean peptide concentration RC-C samples (mM)	0.50 ± 0.05	0.499 ± 0.005	0.50 ± 0.05	0.515 ± 0.002
Mean peptide concentration RC-CMQsamples (mM)	0.50 ± 0.05	0.495 ± 0.001	0.50 ± 0.05	0.520 ± 0.005
CV (%) for RC samples B and C	<15.0	0.9	<15.0	3.2
Mean peptide depletion cinnamic aldehyde (%)	60.8-100	73.5	40.2-69.0	68.3
SD of peptide depletion cinnamic aldehyde (%)	<14.9	0.1	<11.6	0.4
SD of peptide depletion for the test item (%)	<14.9	0.0	<11.6	2.6

RC = Reference Control; CV = Coefficient of Variation; SD = Standard Deviation.

Table 5 SPCC and SPCL Depletion, DPRA Prediction and Reactivity Classification for the Test Item

Test item	SPCC depletion		SPCL depletion		Mean of SPCC and SPCL depletion	DPRA prediction and reactivity classification
	Mean	± SD	Mean	± SD		Cysteine 1:10 / Lysine 1:50 prediction model
4-(cyclohexylamino)butane1-sulfonic acid	0.0%	±0.0%	1.5%	±2.6%	0.7%	Negative: No or minimal reactivity

SD = Standard Deviation.

Interpretation of results:

other: study is part of a weight of evidence approach and is not used for classification on its own

Conclusions:

The test substance tested negative in DPRA , performed according to OECD guideline 442C and in accordance with GLP principles, and was classified in the "No or minimal reactivity class” when using the Cysteine 1:10 / Lysine 1:50 prediction model.

Executive summary:

In an in chemico (DPRA) study, performed according to OECD guideline 442C and in accordance with GLP principles, the reactivity of the test substance towards model synthetic peptides containing either cysteine (SPCC) or lysine (SPCL) was determined. Following incubation of the test substance with either SPCC or SPCL, the relative peptide concentration was determined by High-Performance Liquid Chromatography (HPLC) with gradient elution and spectrophotometric detection at 220 nm and 258 nm. SPCC and SPCL Percent Depletion Values were calculated and used in the prediction model. Milli-Q water (MQ) was found to be an appropriate solvent to dissolve the test substance, and was therefore used in this DPRA study. Cinnamic aldehyde was used as a positive control. All acceptability criteria were met and therefore, the study was considered to be valid. No precipitate or phase separation was observed in any of the samples before and after the incubation. In the cysteine reactivity assay the test item showed 0.0% SPCC depletion and in the lysine reactivity assay the test item showed 1.5% SPCL depletion. The mean of the SPCC and SPCL depletion was 0.7% and as a result the test item was considered to be negative in the DPRA and classified in the “no or minimal reactivity class” when using the Cysteine 1:10 / Lysine 1:50 prediction model.

Reference 3

Endpoint:

skin sensitisation: in vitro

Type of information:

experimental study

Adequacy of study:

weight of evidence

Study period:

23 April 2019 - 07 Jun 2019

Reliability:

1 (reliable without restriction)

Rationale for reliability incl. deficiencies:

guideline study

Justification for type of information:

One of the validated in vitro skin sensitization tests is the KeratinoSensTM assay, which is recommended in international guidelines (e.g. OECD) and mentioned in the ECHA guidance as the in vitro test to be performed as part of weight of evidence.

Qualifier:

according to guideline

Guideline:

OECD Guideline 442D (In Vitro Skin Sensitisation: ARE-Nrf2 Luciferase Test Method)

Version / remarks:

June 2018

Deviations:

no

Qualifier:

according to guideline

Guideline:

other: EURL ECVAM DB-ALM Protocol n° 155: KeratinoSens™

Version / remarks:

March 2018

Deviations:

no

GLP compliance:

yes (incl. QA statement)

Type of study:

ARE-Nrf2 luciferase KeratinoSens™ test method

Justification for non-LLNA method:

In the interest of sound science and animal welfare, a sequential testing strategy is recommended to minimize the need of in vivo testing. One of the validated in vitro skin sensitization tests is the KeratinoSensTM assay, which is recommended in international guidelines (e.g. OECD 442D).

Details of test system:

Keratinoses transgenic cell line [442D]

Details on the study design:

Based on a solubility test, a concentration of 2000 μM was selected as highest concentration for the main assay (highest dose required in the guideline).

In the main experiments the test item was dissolved in Milli-Q water at 200 mM (colourless). From this stock 11 spike solutions in Milli-Q water were prepared (2-fold dilution series).
The stock and spike solution were diluted 25-fold with exposure medium. These solutions were diluted 4-fold with exposure medium in the assay resulting in final test concentrations of 2000, 1000, 500, 250, 125, 63, 31, 16, 7.8, 3.9, 2.0 and 0.98 μM (final concentration Milli-Q of 1%). All concentrations of the test item were tested in triplicate.

Test item concentrations were used within 2.5 hours after preparation.

CONTROL ITEMS
- Positive control: ethylene dimethacrylate glycol (tested in triplicate)
-Amount used: 0.78 to 25 mM in DMSO, diluted so that the final concentration ranged from 7.8 to 250 μM (final concentration DMSO of 1%)
- Negative control: 1% Milli-Q in exposure medium and 1% DSMO in exposure medium (eighteen wells per solvent control)
- Blank control: on each plate three bank wells were tested (no cells and no treatment)

TEST DESIGN
- Test system: The KeratinoSens™ cell line, having a stable insertion of the luciferase reporter gene under the control of the ARE-element is used. Upon receipt, cells are propagated (e.g. 2 to 4 passages) and stored frozen as a homogeneous stock. Cells from this original stock can be propagated up to a maximum passage number (i.e. 25) and are employed for routine testing using the appropriate maintenance medium.

- Plating of cells: For testing, cells were 80-90% confluent. One day prior to testing cells were harvested, and distributed into 96-well plates (10,000 cells/well) in basic medium. For each repetition, three replicates were used for the luciferase activity measurements, and one parallel replicate used for the MTT cell viability assay. The cells were incubated overnight in the incubator. The passage number used was P+9 in experiment 1 and P+22 in experiment 2.

- Treatment of cells: The medium was removed and replaced with fresh culture medium (150 μL culture medium containing serum but without Geneticin) to which 50 μL of the 25-fold diluted test chemical and control items were added. Three wells per plate were left empty (no cells and no treatment) to assess background values. The treated plates were covered with foil and then incubated for about 48 ± 1 hours at 37±1.0°C in the presence of 5% CO2. In total 2 valid experiments were performed.

- Luciferase activity measurement: The Steady-Glo Luciferase Assay Buffer (10 mL) and Steady-Glo Luciferase Assay Substrate (lyophilized) from Promega were mixed together. The assay plates were removed from the incubator and the medium is removed. Then 200 µL of the Steady-Glo Luciferase substrate solution (prior to addition 1:1 mixed with exposure medium) was added to each well. The plates were shaken for at least 5 minutes at room temperature. Plates with the cell lysates were placed in a microplate reader to assess the quantity of luciferase (integration time two seconds).

- Cytotoxicity assessment: For the KeratinoSensTM cell viability assay, medium was replaced after the 48 hour exposure time with fresh medium containing MTT (3-(4,5-Dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide, thiazolyl blue tetrazolium bromide and subsequently cells were incubated for 3 - 4 hours at 37°C ±1.0°C in the presence of 5% CO2. The MTT medium was then removed and cells were lysed overnight by adding 10% SDS solution to each well. After shaking, the absorption was measured at 570 nm with a microplate reader.

The KeratinoSensTM test is considered acceptable if it meets the following criteria:
a) The luciferase activity induction obtained with the positive control, Ethylene dimethacrylate glycol, should be statistically significant equal or above the threshold of 1.5 in at least one of the tested concentrations (from 7.8 to 250 μM).
b) The EC1.5 should be within two standard deviations of the historical mean. Moreover, the induction for Ethylene dimethacrylate glycol at 250 μM should be higher than 2- fold. If the latter criterion is not fulfilled, the dose-response of Ethylene dimethacrylate glycol should be carefully checked, and tests may be accepted only if there is a clear dose-response with increasing luciferase activity induction at increasing concentrations for the positive control.
c) The average coefficient of variation of the luminescence reading for the vehicle (negative) control Milli-Q water should be below 20% in each repetition which consists of 18 wells tested. If the variability is higher, results should be discarded. If the variability is higher, a maximum of three of the eighteen wells may be excluded based on the Dixon’s Q-test (2). If the variability is still higher, the results should be discarded.
d) the average coefficient of variation of the luminescence reading for the vehicle (negative) control DMSO should be below 20% in each repetition which consists of 18 wells tested. If the variability is higher, results should be discarded. If the variability is higher, a maximum of three of the eighteen wells may be excluded based on the Dixon’s Q-test (2). If the variability is still higher, the results should be discarded.

A KeratinoSensTM prediction is considered positive if the following 4 conditions are all met in 2 of 2 or in the same 2 of 3 repetitions, otherwise the KeratinoSensTM prediction is considered negative:
1. The Imax is equal or higher than (≥) 1.5 fold and statistically significantly different as compared to the vehicle (negative) control (as determined by a two-tailed, unpaired Student’s t-test)
2. The cellular viability is higher than (>) 70% at the lowest concentration with induction of luciferase activity ≥ 1.5 fold (i.e. at the EC1.5 determining concentration)
3. The EC1.5 value is less than (<) 1000 μM (or < 200 μg/mL for test chemicals with no defined MW)
4. There is an apparent overall dose-response for luciferase induction

Negative results obtained with concentrations <1000 μM or 200 μg/mL and which do not reach cytotoxicity (< 70% viability) at the maximal tested concentration should be considered as inconclusive.

Positive control:

EGDMA (120 M) [442D]

Positive control results:

Experiment 1: The positive control Ethylene dimethacrylate glycol caused a dose related induction of the luciferase activity. The Imax was 3.67 and the EC1.5 29 µM.
Experiment 2: The positive control Ethylene dimethacrylate glycol caused a dose related induction of the luciferase activity. The Imax was 3.32 and the EC1.5 38 µM.

Key result

Group:

test chemical

Run / experiment:

run/experiment 1

Parameter:

Imax [442D]

Value:

1.12

Vehicle controls validity:

valid

Negative controls validity:

not applicable

Positive controls validity:

valid

Remarks on result:

other: EC1.5: could not be calculated

Key result

Group:

test chemical

Run / experiment:

run/experiment 2

Parameter:

Imax [442D]

Value:

1.02

Vehicle controls validity:

valid

Negative controls validity:

not applicable

Positive controls validity:

valid

Remarks on result:

other: EC1.5: could not be calculated

Outcome of the prediction model:

negative [in vitro/in chemico]

Other effects / acceptance of results:

Both tests passed the acceptance criteria:
- The luciferase activity induction obtained with the positive control, Ethylene dimethacrylate glycol, was statistically significant above the threshold of 1.5-fold in at least one concentration.
- The EC1.5 of the positive control was within two standard deviations of the historical mean (29 μM and 38 μM in experiment 1 and 2, respectively). A dose response was observed and the induction at 250 μM was higher than 2-fold (3.67-fold and 3.32-fold in experiment 1 and 2, respectively).
- The average coefficient of variation of the luminescence reading for the vehicle (negative) control Milli-Q water was below 20% (4.2% and 4.1% in experiment 1 and 2, respectively).
- The average coefficient of variation of the luminescence reading for the vehicle (negative) control DMSO was below 20% (6.4% and 4.7% in experiment 1 and 2, respectively).

Cytotoxicty
No cytotoxicity was observed and therefore no IC30 and IC50 values were calculated.

Prepcipitation
No precipitation was observed at the start and end of the incubation period.

Interpretation of results:

other: study is part of a weight of evidence approach and is not used for classification on its own

Conclusions:

4-(cyclohexylamino)Butane-1-sulfonic acid is classified as negative in the KeratinoSensTM assay, performed according to OECD guideline 442D and in accordance with GLP principles, since negative results (<1.5-fold induction) were observed at test concentrations up to and including 2000 μM.

Executive summary:

A KeratinoSensTM assay was performed with the substance according to OECD 442D and in accordance with GLP principles. Two valid independent experiments were performed. The cells in these experiments were incubated with the test item in a concentration range of 0.98 – 2000 µM (2-fold dilution steps) for 48 ± 1 hours. Positive controls and vehicle controls were included. All acceptability criteria were met and therefore the study was considered to be valid. The test item showed no precipitation, no toxicity (no IC30 and IC50 value) and no biologically relevant induction of the luciferase activity (no EC1.5 value) were measured at any of the test concentrations in both experiments. The maximum luciferase activity induction (Imax) was 1.12-fold and 1.02-fold in experiment 1 and 2, respectively. Based on these results 4-(cyclohexylamino)butane-1-sulfonic acid is classified as negative in the KeratinoSensTM assay since negative results (<1.5-fold induction) were observed at test concentrations up to and including 2000 μM.

Endpoint conclusion

Endpoint conclusion:

no adverse effect observed (not sensitising)

Additional information:

No data were available that would preclude performance of the studies to determine the potential for skin sensitization. Therefore, STEP 1 studies were performed, i.e. a DEREK assessment (Charles River study no 20191850), a DPRA (Charles River study no 20191851) and a KeratinoSensTM assay (Charles River study no 20191852).

 

DEREK NEXUS version 6.0.1 did not yield any alerts for skin sensitization of the test item. Additionally, the query structure does not contain any unclassified or misclassified features and is consequently predicted to be a non-sensitizer. A valid DPRA was performed according to OECD TG 442C and in accordance with GLP principles. For the DPRA 4-(cyclohexylamino)butane-1-sulfonic acid was dissolved in Milli- Q at 100 mM and formed a clear solution (as judged by visual inspection). Upon preparation as well as after incubation of model synthetic peptides containing either cysteine (SPCC) or lysine (SPCL) with the test item no precipitate or phase separation was observed in any of the samples. No co-elution of the test item with SPCC or SPCL was observed. In the cysteine and lysine reactivity assay the test item showed 0.0% SPCC and 1.5% SPCL depletion, respectively. The mean of the SPCC and SPCL depletion was 0.7%. According to the Cysteine 1:10 / Lysine 1:50 prediction model 4-(cyclohexylamino)butane-1-sulfonic acid is classified in the “no or minimal reactivity class” and is considered to be negative in the DPRA.

 

A valid KeratinoSensTM assay was performed according to OECD TG 442D and in accordance with GLP principles. For the KeratinoSensTM assay 4-(cyclohexylamino)butane- 1-sulfonic acid was dissolved in Milli-Q to a final concentration of 200 mM, and formed a clear colorless solution. Two valid independent tests were performed. No significant cytotoxicity nor precipitation was observed in the experiments. The cells were incubated with 4-(cyclohexylamino)butane-1-sulfonic acid in a concentration range of 0.98 μM – 2000 μM (2-fold dilution series) for 48 hours in both experiments. The test item showed no toxicity (no IC30 and IC50 value) and no biologically relevant induction of the luciferase activity (no EC1.5 value) was measured at any of the test concentrations in both experiments. The maximum luciferase activity induction (Imax) was 1.12-fold and 1.02-fold in experiment 1 and 2 respectively. 4-(cyclohexylamino)butane-1-sulfonic acid classified as negative in the KeratinoSensTM assay since negative results (<1.5-fold induction) were observed at test concentrations up to and including 2000 μM.

 

4-(Cyclohexylamino)butane-1-sulfonic acid was assessed by DEREK and yielded no alerts for skin sensitization. All structural features of 4-(cyclohexylamino)butane-1-sulfonic acid were found in the negative predication database of DEREK, therefore the substance is predicted to be not skin sensitizing to the skin. In the DPRA 4-(cyclohexylamino)butane-1 - sulfonic acid showed no significant interaction with cysteine or lysine and therefore the outcome was negative. In the KeratinoSensTM assay 4-(cyclohexylamino)butane-1-sulfonic acid showed no activation of the antioxidant/electrophile responsive element (ARE)- dependent pathway. Therefore keratinocytes are not expected to be activated after exposure to 4-(cyclohexylamino)butane-1-sulfonic acid. Based on the results obtained in the non-animal skin sensitization testing strategy sufficient evidence is presented to conclude that 4 - (cyclohexylamino)butane-1-sulfonic acid is not a skin sensitizer and is thus not expected to lead to an allergic response following skin contact. Based on this conclusion 4 - (cyclohexylamino)butane-1-sulfonic acid does not need to be classified for skin sensitization according to Regulation (EC) No 1272/2008 and related amendments.

 

According to the 2o3 DA in OECD 497 (2021) the results of the DPRA and KeratinoSens were negative (non-borderline). As a result the 2o3 DA was conclusive and the substance can be considered a non-sensitizer

Respiratory sensitisation

Endpoint conclusion

Endpoint conclusion:

no study available

Justification for classification or non-classification

Based on the results of the available studies and according to the 2o3 defined approach in OECD 497 the test item can be considerd a non-sensitzer. The substance does not need to be classified for skin sensitization according to Regulation (EC) No 1272/2008 on classification, labelling and packaging of items and mixtures (including all amendments).