trans-1-butyl-4-[trans-4-[(E)-prop-1-enyl]cyclohexyl]cyclohexane

Endpoint summary

Description of key information

Skin sensitisation was investigated using GLP in vitro studies performed according to OECD TG 442C-E. The following results have been obtained:

• OECD 442C: negative
• OECD 442D: technically impossible due to limited solubility
• OECD 442E: technically impossible due to limited solubility

The in vitro data are insufficient to conclude on the endpoint of skin sensitisation. Therefore, an additional in vivo LLNA study according to OECD 429 was performed. The test item was found to be a skin sensitiser and an EC3 value of 6.4% (w/w) was derived.

Key value for chemical safety assessment

Skin sensitisation

Link to relevant study records

Reference

Reference 1

Endpoint:

skin sensitisation: in chemico

Type of information:

experimental study

Adequacy of study:

weight of evidence

Study period:

June 02 - Nov 2019

Reliability:

1 (reliable without restriction)

Rationale for reliability incl. deficiencies:

guideline study

Qualifier:

according to guideline

Guideline:

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

Qualifier:

according to guideline

Guideline:

other: Direct Peptide Reactivity Assay (DPRA) for Skin Sensitization Testing, DB-ALM Protocol n°154, January 12, 2013

GLP compliance:

yes (incl. QA statement)

Remarks:

Behörde für Gesundheit und Verbraucherschutz, Freie Handelsstadt Hamburg

Type of study:

direct peptide reactivity assay (DPRA)

Details on the study design:

The in chemico direct peptide reactivity assay (DPRA) enables detection of the sensitising potential of a test item by quantifying the reactivity of test chemicals towards synthetic peptides containing either lysine or cysteine.

Positive control results:

The 100 mM stock solution of the positive control (cinnamic aldehyde) showed high reactivity towards the synthetic peptides. The mean depletion of both peptides was 68.60%.

Key result

Run / experiment:

other: cysteine run

Parameter:

other: mean peptide depletion [%]

Value:

0

Vehicle controls validity:

valid

Negative controls validity:

valid

Positive controls validity:

valid

Key result

Run / experiment:

other: lysine run

Parameter:

other: mean peptide depletion [%]

Value:

0

Vehicle controls validity:

valid

Negative controls validity:

valid

Positive controls validity:

valid

Other effects / acceptance of results:

Acceptance Criteria

The following criteria must be met for a run to be considered valid:
a) The standard calibration curve should have an r2 > 0.99.
b) The mean percent peptide depletion value of the three replicates for the positive control cinnamic aldehyde should be between 60.8% and 100% for the cysteine peptide and between 40.2% and 69.0% for the lysine peptide and the maximum standard deviation (SD) for the positive control replicates should be < 14.9% for the percent cysteine depletion and < 11.6% for the percent lysine depletion.
c) The mean peptide concentration of reference controls A should be 0.50 ± 0.05 mM and the coefficient of variation (CV) of peptide peak areas for the nine reference controls B and C in acetonitrile should be <15.0%.
If one or more of these criteria is not met, the run would have been repeated.

The following criteria must be met for a test item’s results to be considered valid:
a) The maximum standard deviation for the test item replicates should be < 14.9% for the percent cysteine depletion and < 11.6% for the percent lysine depletion.
b) The mean peptide concentration of the three reference controls C in the appropriate solvent should be 0.50 ± 0.05 mM.

If these criteria were not met, the data would have been rejected and the run have been repeated for that specific test item.

Peptide Depletion in %

1) Cystein Depletion

Sample	Peak Area	Actual Peptide [mM]	Peak Are Ref Control C	Peptide Depletion [%]	Corr. peptide Depletion [%]
1	50.9758	0.503	50.8281	-0.03	0.00
2	51.5350	0.509	51.0861	-1.13	0.00
3	51.5140	0.508	50.9661	-1.09	0.00
Mean	51.342	0.507	50.9601	-0.75	0.00
Evaluation Reactivity Class. Negative

1) Lysine Depletion

Sample	Peak Area	Actual Peptide [mM]	Peak Are Ref Control C	Peptide Depletion [%]	Corr. peptide Depletion [%]
1	36.3497	0.464	35.0532	-2.95	0.00
2	36.4728	0.465	35.3563	-3.29	0.00
3	36.5649	0.466	35.5197	-3.55	0.00
Mean	36.462	0.465	35.3097	-3.26	0.00
Evaluation Reactivity Class. Negative

Interpretation of results:

other: The result has to be considered in an integrated approach.

Conclusions:

The test material revealed a mean cysteine and lysine peptide depletion of 0.0% and, hence, the test item is considered negative and predicted to be a non-sensitiser (no or minimal reactivity) in the Direct Peptide Reactivity Assay (DPRA).

Executive summary:

Pupose

The purpose of this study was to determine the sensitising potential of the test material in a Direct Peptide Reactivity Assay (DPRA).

Methods

The study was performed according to OECD guideline 442C. The DPRA is an in chemico method which quantifies the remaining concentration of cysteine- or lysine-containing peptide following incubation with the test item. Cysteine and lysine peptide percent depletion values are then calculated and used in a prediction model, which allows assigning the test item to one of four reactivity classes used to support the discrimination between sensitisers and nonsensitisers.

Results

The test item was dissolved at a concentration of 100 mM in acetone. No precipitate in the reaction mixture at the end of the incubation time and no co-elution were observed.

The test material-treated samples revealed a cysteine peptide depletion of 0.0% and a lysine peptide depletion of 0.0% (mean peptide depletion of 0.0%) and, hence, were well

below 6.38%. The test material is considered negative and predicted to be a nonsensitiser (no or minimal reactivity) in the Direct Peptide Reactivity Assay (DPRA).

Cinnamic aldehyde was used as positive control at a concentration of 100 mM in acetone. Treatment with the positive control item revealed a cysteine and lysine peptide depletion of

68.65% for cysteine and 59.73% for lysine peptide. These values are within the required range. Therefore, the study can be regarded as valid.

Conclusion

The test material revealed a mean cysteine and lysine peptide depletion of 0.0% and, hence, the test item is considered negative and predicted to be a non-sensitiser (no or

minimal reactivity) in the Direct Peptide Reactivity Assay (DPRA).

Reference 2

Endpoint:

skin sensitisation: in vitro

Study period:

Jun 03 - Sep 17, 2019

Data waiving:

study technically not feasible

Justification for data waiving:

other:

Justification for type of information:

JUSTIFICATION FOR DATA WAIVING
The test item appeared to be insoluble in the required concentration in water. The test item was insoluble in DMSO at the required stock solution concentration of 200 mM and formed no stable suspension after addition of treatment medium. Since the KeratinoSens assay is not suitable for test items which precipitate into non stable suspensions or emulsions (defined by OECD 442D) the test item has to be considered as being technically impossible in this test.

Qualifier:

according to guideline

Guideline:

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

Qualifier:

according to guideline

Guideline:

other: KeratinoSens™, EURL ECVAM DB-ALM Protocol No. 155, July 1st, 2015

GLP compliance:

yes (incl. QA statement)

Remarks:

Behörde für Gesundheit und Verbraucherschutz, Freie Handelsstadt Hamburg

Type of study:

activation of keratinocytes

Details on the study design:

The in vitro KeratinoSens™ assay enables detection of the sensitising potential of a test item by addressing the second molecular key event of the adverse outcome pathway (AOP), namely activation of keratinocytes, by quantifying the luciferase activity in the transgenic cell line KeratinoSens™. The luciferase activity, assessed by luminescence measurement, compared to the respective solvent controls is used to support discrimination between skin sensitisers and non-sensitisers.

Interpretation of results:

study cannot be used for classification

Conclusions:

Since the KeratinoSens assay is not suitable for test items which precipitate into non stable suspensions or emulsions (defined by OECD 442D) the test item has to be considered as being technically impossible in this test.

Reference 3

Endpoint:

skin sensitisation: in vitro

Study period:

Jul 29 - Aug 27, 2019

Data waiving:

study technically not feasible

Justification for data waiving:

other:

Justification for type of information:

JUSTIFICATION FOR DATA WAIVING
The test item appeared to be insoluble in the required concentration in medium and DMSO. Since the h-CLAT assay is not suitable for non-stable suspensions or emulsions the test system has to be considered unsuitable for this test item.

Qualifier:

according to guideline

Guideline:

other: OECD Guidelines for Testing of Chemicals, No. 442E: In Vitro Skin Sensitisation assays addressing the Key Event on activation of dendritic cells on the Adverse Outcome Pathway for Skin Sensitisation”, adopted 25 June 2018

Qualifier:

according to guideline

Guideline:

other: Human Cell Line Activation Test (h-CLAT) for Skin Sensitisation, DB-ALM Protocol n°158, July 1st, 2015

GLP compliance:

yes (incl. QA statement)

Remarks:

Behörde für Gesundheit und Verbraucherschutz, Freie Handelsstadt Hamburg

Type of study:

activation of dendritic cells

Interpretation of results:

study cannot be used for classification

Conclusions:

The test item appeared to be insoluble in the required concentration in medium and DMSO. Since the h-CLAT assay is not suitable for non-stable suspensions or emulsions the test system has to be considered unsuitable for this test item.

Reference 4

Endpoint:

skin sensitisation: in vivo (LLNA)

Type of information:

experimental study

Adequacy of study:

weight of evidence

Study period:

Dec 04, 2019 - Feb 18, 2020

Reliability:

1 (reliable without restriction)

Rationale for reliability incl. deficiencies:

guideline study

Qualifier:

according to guideline

Guideline:

OECD Guideline 429 (Skin Sensitisation: Local Lymph Node Assay)

Deviations:

no

Qualifier:

according to guideline

Guideline:

EU Method B.42 (Skin Sensitisation: Local Lymph Node Assay)

Deviations:

no

GLP compliance:

yes (incl. QA statement)

Type of study:

mouse local lymph node assay (LLNA)

Species:

mouse

Strain:

CBA

Sex:

female

Details on test animals and environmental conditions:

TEST ANIMALS
- Source: Envigo RMS B.V., Inc Postbus 6174 5960 AD Horst / The Netherlands
- Age at study initiation: Pre-test test: 8 - 9weeks
Main Test: 9 - 10 weeks
- Weight : 17.0 - 23.6 g
- Housing: grouped per dose
- Diet (e.g. ad libitum): ad libitum
- Water (e.g. ad libitum): ad libitum
- Acclimation period: 5 days

ENVIRONMENTAL CONDITIONS
- Temperature (°C): 22 + 2°C
- Humidity (%): 20-70%
- Photoperiod (hrs dark / hrs light): 12/12

IN-LIFE DATES: From: day 1 To: day 6

Vehicle:

propylene glycol

Concentration:

5, 10, and 25 (w/w)

No. of animals per dose:

5

Details on study design:

RANGE FINDING TESTS:
- Compound solubility: 50% in MEK

Range Finding Exp. 1
- Concentration used: 25, 50 %
- Irritation:erythema of the ear skin (Score up to 3)

Range Finding Exp. 2
- Concentration used: 5, 10 %
- Irritation:very slight erythema of the ear skin (Score 1)



MAIN STUDY
ANIMAL ASSIGNMENT AND TREATMENT
- Name of test method: OECD 429
- Concentration: 2.5, 5, and 10%
- Criteria used to consider a positive response: Stimulation index > 3

Positive control substance(s):

hexyl cinnamic aldehyde (CAS No 101-86-0)

Statistics:

Standard statistical methods have been applied for data processing.

Positive control results:

Conc. SI
0%: 1.0
5% 1.68
10% 1.78
25% 8.19

Key result

Parameter:

SI

Value:

1.5

Test group / Remarks:

Test Group: 2.5% in MEK

Key result

Parameter:

SI

Value:

2.5

Test group / Remarks:

Test Group: 5% in MEK

Key result

Parameter:

SI

Value:

4.3

Test group / Remarks:

Test Group: 10% in MEK

Key result

Parameter:

EC3

Value:

6.4

Cellular proliferation data / Observations:

EC3 CALCULATION : EC3 = (a-c) [(3-d)/(b-d)] + c; a,b,c,d = coordinates of the two pairs of data lying immediately above and below the S.I. value of 3 on the LLNA dose response plot

CLINICAL OBSERVATIONS: The animals did not show any signs of systemic toxicity during the course of the study and no cases of mortality were observed. The animals treated with test item concentrations of 5 and 10% showed a very slight erythema of the ear skin (Score 1). Animals treated with 2.5% test item concentration did not show any signs of local skin irritation.

BODY WEIGHTS: The body weight of the animals, recorded prior to the first application and prior to treatment with 3HTdR, was within the range commonly recorded for animals of this strain and age.

Calculation of Stimulation Indices per Dose Group

Test item concentration	Group Calculation
	Mean DPM per animal (2 lymph nodes)	SD	S.I.
MEK (Vehicle Control)	1415.6	231.6	1.0
2.5 % Test Item in MEK	2166.8	714.2	1.5
5 % Test Item in MEK	3574.4	764.0	2.5
10 % Test Item in MEK	6064.6	2110.7	4.3

Interpretation of results:

Category 1B (indication of skin sensitising potential) based on GHS criteria

Conclusions:

The test item was found to be a skin sensitiser and an EC3 value of 6.4% (w/w) was derived.

Executive summary:

Objective

In the study the test item formulated in methyl ethyl ketone (MEK) was assessed for its possible skin sensitising potential.

Study Design

For this purpose a local lymph node assay was performed using test item concentrations of 2.5, 5, and 10 (w/w). The highest concentration tested was the highest concentration that could technically be achieved.

Results

The animals did not show any signs of systemic toxicity or local skin irritation during the course of the study and no cases of mortality were observed.

The animals treated with test item concentrations of 5 and 10% showed a very slight erythema of the ear skin (Score 1). Animals treated with 2.5% test item concentration did not show any signs of local skin irritation.

In this study Stimulation Indices (S.I.) of 1.5, 2.5, and 4.3 were determined with the test item at concentrations of 2.5, 5, and 10% in MEK, respectively. A clear dose response was observed.

Conclusion

The test item was found to be a skin sensitiser and an EC3 value of 6.4% (w/w) was derived.

Endpoint conclusion

Endpoint conclusion:

adverse effect observed (sensitising)

Additional information:

In vitro skin sensitisation

The KeratinoSens Assay as well as the h-Clat are technical impossible due to the limited solubility of the test item in the solvents according to the appropriate OECD Guideline.

In the Directive Peptide Reactivity Assay (DPRA), the test material revealed a mean cysteine and lysine peptide depletion of 0.0% and, hence, the test item is considered negative and predicted to be a non-sensitiser (no or minimal reactivity) .

However, the in vitro data are insufficient for a conclusion on classification an labelling and therefore an in vivo LLNA assay according to OECD 429 was conducted.

In vivo skin sensitization test

In this study Stimulation Indices (S.I.) of 1.5, 2.5, and 4.3 were determined with the test item at concentrations of 2.5, 5, and 10% in MEK, respectively. A clear dose response was observed. The test item was found to be a skin sensitiser and an EC3 value of 6.4% (w/w) was derived.

Respiratory sensitisation

Endpoint conclusion

Endpoint conclusion:

no study available

Justification for classification or non-classification

Based on the provided information a classification according to the EU Regulation (EC) No 1272/2008 on Classification, Labelling and Packaging of Substances and Mixtures for skin sensitisation in Class 1B (H317) is justified.