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Administrative data

Description of key information

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

In-Vitro Skin Sensitization: Positive in human Cell Line Activation Test (h-CLAT) (OECD TG 442E)

(Q)SAR- 5 out of 15 (33%) hypothetical structures based on chemistry of UVCB manufacturing process positive for sensitization

See field "Additional information" for weight of evidence evaluation of overall skin sensitisation potential.

Key value for chemical safety assessment

Skin sensitisation

Link to relevant study records

Referenceopen allclose all

Endpoint:
skin sensitisation, other
Type of information:
(Q)SAR
Adequacy of study:
weight of evidence
Reliability:
2 (reliable with restrictions)
Rationale for reliability incl. deficiencies:
results derived from a valid (Q)SAR model, but not (completely) falling into its applicability domain, with adequate and reliable documentation / justification
Justification for type of information:
Justification for type of information
1. SOFTWARE
OASIS TIMES v.2.27.17

2. MODEL (incl. version number)
Skin sensitization with autoxidation v.20.24 June 2015

3. SMILES OR OTHER IDENTIFIERS USED AS INPUT FOR THE MODEL
Potential hypothetical structures have been proposed based on the chemistry of the manufacturing process for the UVCB. See attached QPRF.

4. SCIENTIFIC VALIDITY OF THE (Q)SAR MODEL
See attached QMRF

5. APPLICABILITY DOMAIN
See attached QPRF

6. ADEQUACY OF THE RESULT
See attached QPRF
Guideline:
other: REACH Guidance on QSARs R.6
Principles of method if other than guideline:
- Software tool(s) used including version: OASIS TIMES v.2.27.17
- Model(s) used: Skin sensitization with autoxidation v.20.24 June 2015
- Model description: see field 'Attached justification'
- Justification of QSAR prediction: see field 'Attached justification'
Key result
Parameter:
other: QSAR Prediction
Remarks on result:
other: From Sensitizing to Non-Sensitizing

The QSAR prediction for hypothetical potential structures within this UVCB substance ranged from non-sensitizing to sensitizing. Approximately 33% (5/15) of the hypothetical structures were considered positive by their very nature or due to autoxidation transformations; particularly, those hypothetical potential structures with free hydrazine functional groups were predicted as positive.

Interpretation of results:
other: From Non-Sensitizing to Sensitizing
Conclusions:
The prediction for hypothetical structures within this UVCB substance ranged from non-sensitizing to sensitizing. Approximately 33% (5/15) of the hypothetical structures were considered positive by their very nature or due to autoxidation transformations.
Executive summary:

A (Q)SAR prediction for skin sensitization was generated using the Skin Sensitization with autoxidation v.20.24 model of the OASIS TIMES v.2.27.17 software. Hypothetical potential structures were generated based on the chemistry of the reactants and manufacturing process. The prediction for hypothetical structures within this UVCB substance ranged from non-sensitizing to sensitizing. Approximately 33% (5/15) of the hypothetical structures were considered positive by their very nature or due to autoxidation transformations. The result is not considered adequate on its own for the regulatory purpose as the majority of the hypotehtical chemical structures fall outside of the structural applicability domain. Additional information is required such as in-vitro testing or in-vivo data, all of which will be considered within a weight of evidence approach to make a final determination on skin sensitization.

Endpoint:
skin sensitisation: in vitro
Remarks:
Human Cell Line Activation Test
Type of information:
experimental study
Adequacy of study:
weight of evidence
Study period:
01 Oct 2017 - 16 Feb 2018
Reliability:
1 (reliable without restriction)
Rationale for reliability incl. deficiencies:
guideline study
Qualifier:
according to guideline
Guideline:
other: OECD 442E In-Vitro Skin Sensitization: Human Cell Line Activation Test (hCLAT)
Version / remarks:
29 July 2016
Deviations:
no
Principles of method if other than guideline:
- Principle of test: The h-CLAT method is an in vitro assay that quantifies changes of cell surface marker expression (i.e. CD86 and CD54) on a human monocytic leukemia cell line, THP-1 cells, following 24 hours exposure to the test chemical. These surface molecules are typical markers of monocytic THP-1 activation and may mimic DC activation, which plays a critical role in T-cell priming. The changes of surface marker expression are measured by flow cytometry following cell staining with fluorochrome-tagged antibodies. Cytotoxicity measurement is also conducted concurrently to assess whether upregulation of surface marker expression occurs at sub-cytotoxic concentrations. The relative fluorescence intensity of surface markers compared to solvent/vehicle control are calculated and used in the prediction model, to support the discrimination between sensitisers and non-sensitisers.
GLP compliance:
yes
Type of study:
activation of dendritic cells
Specific details on test material used for the study:
SOURCE OF TEST MATERIAL
- Source and lot/batch No. of test material: BASF (Puebla, Mexico) batch# 6191104
- Expiration date of the lot/batch: August 2018
- Purity test date: 08 March 2017

STABILITY AND STORAGE CONDITIONS OF TEST MATERIAL
- Storage condition of test material: stored at room temperature
- Stability under test conditions: stable under conditions of assay
- Solubility and stability of the test substance in the solvent/vehicle: soluble in vehicle based on initial solubility screen

TREATMENT OF TEST MATERIAL PRIOR TO TESTING
- Treatment of test material prior to testing: used as received
Details on the study design:
The h-CLAT method is an in vitro assay that quantifies changes of cell surface marker expression (i.e. CD86 and CD54) on a human monocytic leukemia cell line, THP-1 cells, following 24 hours exposure to the test chemical. These surface molecules are typical markers of monocytic THP-1 activation and may mimic DC activation, which plays a critical role in T-cell priming. The changes of surface marker expression are measured by flow cytometry following cell staining with fluorochrome-tagged antibodies. Cytotoxicity measurement is also conducted concurrently to assess whether upregulation of surface marker expression occurs at sub-cytotoxic concentrations. The relative fluorescence intensity of surface markers compared to solvent/vehicle control are calculated and used in the prediction model, to support the discrimination between sensitisers and non-sensitisers

THP-1 cells are cultured, at 37°C under 5% CO2 and humidified atmosphere, in RPMI-1640 medium supplemented with 10% foetal bovine serum (FBS), 0.05 mM 2-mercaptoethanol, 100 units/mL penicillin and 100 μg/mL streptomycin. The positive controls for this assay are 2,4-dinitrochlorobenzene (DNCB) (CAS n. 97-00-7, ≥ 99% purity) and nickel sulfate (NiSO4) (CAS n. 10101-97-0, ≥ 99% purity) and the negative control, is lactic acid (LA) (CAS n. 50-21-5, ≥ 85% purity).

A dose finding assay is performed to determine the CV75, being the test chemical concentration that results in 75% cell viability (CV) compared to the solvent/vehicle control. The CV75 value is used to determine the concentration of test chemicals for the main assay involving CD86/CD54 expression measurement. The test substance working solutions are mixed 1:1 (v/v) with the cell suspensions prepared in the 24-well or 96-well flat-bottom plate. The treated plates are then incubated for 24±0.5 hours at 37°C under 5% CO2. After 24±0.5 hours of exposure, CD54/86 expression is measured by FITC-labelled anti-CD86, anti-CD54 or mouse IgG1 (isotype) antibodies at 4°C for 30 min. Cell viability was measured by Propidium Iodine staining.

ACCEPTANCE OF RESULTS:
- Acceptance criteria met for negative control: Cell viabilities of medium and solvent/vehicle controls should be > 90%. The RFI values of both CD86 and CD54 should not exceed positive crtieria (CD86 RFI ≥ 150% and CD54 RFI ≥ 200%). The MFI ratio of both CD86 and CD54 to isotype control should be > 105%.
-Acceptance criteria for positive control: RFI values of both CD86 and CD54 should meet the positive criteria CD86 RFI ≥ 150% and CD54 RFI ≥ 200% and cell viability should be more than 50%.
-Acceptance criteria for test chemicals: Cell viability should be more than 50% in at least four tested concentrations. Negative results are acceptable only for test chemicals exhibiting a cell viability of less than 90% at the highest concentration tested, unless 5000 ug/mL is used as the maximal test concentration of a test chemical than a negative result is acceptable even if the cell viability is above 90%.

Positive control results:
The positive control 2,4-dinitrochlorobenzene (DNCB) produced positive results (CD86 RFI ≥ 150% and CD54 RFI ≥ 200%) in three out of five replicates. The positive control nickel sulfate (NiSO4) produced positive results (CD86 RFI ≥ 150% and CD54 RFI ≥ 200%) in all five replicates.
Key result
Run / experiment:
other: mean of three replicates
Parameter:
other: CV75 (ug/mL)
Remarks:
estimated concentration causing 75% viability
Value:
56.2
Run / experiment:
other: CD54 Main Assay #1
Parameter:
other: EC200 (ug/mL)
Value:
32.4
Vehicle controls validity:
valid
Negative controls validity:
valid
Positive controls validity:
not valid
Run / experiment:
other: CD86 Main Assay #1
Parameter:
other: EC150 (ug/mL)
Value:
67.5
Vehicle controls validity:
valid
Negative controls validity:
valid
Positive controls validity:
not valid
Run / experiment:
other: CD54 Main Assay #2
Parameter:
other: EC200 (ug/mL)
Value:
32.4
Vehicle controls validity:
valid
Negative controls validity:
valid
Positive controls validity:
not valid
Run / experiment:
other: CD86 Main Assay #2
Parameter:
other: EC150 (ug/mL)
Value:
67.5
Vehicle controls validity:
valid
Negative controls validity:
valid
Positive controls validity:
not valid
Key result
Run / experiment:
other: CD54 Main Assay #3
Parameter:
other: EC200 (ug/mL)
Remarks:
concentration showing an RFI value >200 in CD54
Value:
56.9
Vehicle controls validity:
valid
Negative controls validity:
valid
Positive controls validity:
valid
Remarks on result:
positive indication of skin sensitisation
Key result
Run / experiment:
other: CD86 Main Assay #3
Parameter:
other: EC150 (ug/mL)
Remarks:
concentration showing an RFI value >150 in CD86
Value:
67.5
Vehicle controls validity:
valid
Negative controls validity:
valid
Positive controls validity:
valid
Remarks on result:
no indication of skin sensitisation
Key result
Run / experiment:
other: CD54 Main Assay #4
Parameter:
other: EC200 (ug/mL)
Remarks:
concentration showing an RFI value >200 in CD54
Value:
67.5
Vehicle controls validity:
valid
Negative controls validity:
valid
Positive controls validity:
valid
Remarks on result:
no indication of skin sensitisation
Key result
Run / experiment:
other: CD86 Main Assay #4
Parameter:
other: EC150 (ug/mL)
Remarks:
concentration showing an RFI value >150 in CD86
Value:
67.5
Vehicle controls validity:
valid
Negative controls validity:
valid
Positive controls validity:
valid
Remarks on result:
no indication of skin sensitisation
Key result
Run / experiment:
other: CD54 Main Assay #5
Parameter:
other: EC200 (ug/mL)
Remarks:
concentration showing an RFI value >200 in CD54
Value:
27.4
Vehicle controls validity:
valid
Negative controls validity:
valid
Positive controls validity:
valid
Remarks on result:
positive indication of skin sensitisation
Key result
Run / experiment:
other: CD86 Main Assay #5
Parameter:
other: EC150 (ug/mL)
Remarks:
concentration showing an RFI value >150 in CD86
Value:
67.5
Vehicle controls validity:
valid
Negative controls validity:
valid
Positive controls validity:
valid
Remarks on result:
no indication of skin sensitisation
Other effects / acceptance of results:
ACCEPTANCE OF RESULTS:
- Acceptance criteria met for negative control: The RFI values of both CD86 and CD54 did not exceed positive crtieria (CD86 RFI ≥ 150% and CD54 RFI ≥ 200%) for the negative control Lactic Acid in any of five replicates.

-Acceptance criteria for positive control: The positive control 2,4-dinitrochlorobenzene (DNCB) did not meet the crtieria for acceptance (CD86 RFI ≥ 150% and CD54 RFI ≥ 200%) in the first two replicates, tehrefore the results of the test substance were considered invalid. The assay was repeated with 3 additional replicates, and DNCB met the acceptance criteria for these additional replicates. The positive control nickel sulfate (NiSO4) met the acceptance crtieria in all 5 replicates.
Interpretation of results:
other: Sensitizing
Conclusions:
The in-vitro Human Cell Line Activation Assay (hCLAT) was used to assess Hydrazine Carboximidamide, 2-((2-hydroxyphenyl)methylene)-, reaction products with 2 undecanone for its potential to activate dendritic cells through measurement of markers CD86 and CD54. A positive result was obtained for CD54 (RFI≥ 200%) in two out of three replicates which resulted in an overall positive h-CLAT prediction. However, this study only gives information on one key event of the skin sensitization AOP and should be assessed with other information within a defined approach or weight of evidence.
Executive summary:

In an OECD TG 442E hCLAT assay, Hydrazine Carboximidamide, 2-((2-hydroxyphenyl)methylene)-, reaction products with 2 undecanone was exposed to THP-1 cells at 67.5, 56.2, 46.7, 38.8, 32.3, 27.0, 22.5, and 18.8 ug/ml based on the initial cytotoxicity screens. A positive result was obtained for CD54 (RFI≥ 200%) in two out of three replicates which resulted in an overall positive h-CLAT prediction. Based on these results, Hydrazine Carboximidamide, 2-((2-hydroxyphenyl)methylene)-, reaction products with 2 undecanone would be predicted as capable of activating dendritic cells (key event #3). Therefore the results of this assay are considered positive and should be used within a weight of evidence for concluding on the skin sensitization potential of Hydrazine Carboximidamide, 2-((2-hydroxyphenyl)methylene)-, reaction products with 2 undecanone under the Regulation (EC) 1272/2008 on classification, labeling, and packaging of substances and mixtures (CLP).

Endpoint:
skin sensitisation: in vitro
Type of information:
experimental study
Adequacy of study:
weight of evidence
Reliability:
2 (reliable with restrictions)
Rationale for reliability incl. deficiencies:
guideline study with acceptable restrictions
Remarks:
Study was not conducted under GLP conditions
Qualifier:
according to guideline
Guideline:
OECD Guideline 442D (In Vitro Skin Sensitisation: ARE-Nrf2 Luciferase Test Method)
Deviations:
no
GLP compliance:
no
Remarks:
Laboratory capacity for GLP-compliant conduct of the OECD 442D Keratinosens was not available during the testing period
Type of study:
activation of keratinocytes
Specific details on test material used for the study:
SOURCE OF TEST MATERIAL
- Source and lot/batch No.of test material: BASF (Puebla, Mexico) batch# 6191104
- Expiration date of the lot/batch: August 2018
- Purity test date: 08 March 2017

STABILITY AND STORAGE CONDITIONS OF TEST MATERIAL
- Storage condition of test material: room temperature
- Stability under test conditions: stable for duration of test
- Solubility and stability of the test substance in the solvent/vehicle: test substance soluble in vehicle (DMSO)
- Reactivity of the test substance with the solvent/vehicle of the cell culture medium: not reactivity noted

TREATMENT OF TEST MATERIAL PRIOR TO TESTING
- Treatment of test material prior to testing: Diluted in vehicle (DMSO)
- Preliminary purification step (if any): not applicable
- Final dilution of a dissolved solid, stock liquid or gel: stock solution of 4% test article in DMSO
- Final preparation of a solid: not applicable
Details on the study design:
The KeratinoSens measures the induction of a luciferase gene expression (Keap1-Nrf2-ARE pathway) alongside cell viability following 48 hours of treatment with test compound.

The KeratinoSens cells are plated on 96-well tissue culture polystyrene plates and quilibrated for 24 hours in low serum media. The test compound is dosed in 12 concentrations on two separate plates, one to determine luminescence and a second to determine cytotoxicity (MTT cell viability). Following an incubation period of 48 hours, cells are either lysed and assessed for the luciferase reporter gene expression using a lumiscent assay or loaded with MTT. After 4 hours the resulting formazan from the MTT cell viability assay is solubilized in a 10% SDS solution and scanned at 570 nm using a mciroplate absorbance reader.

A compound is considered a skin sensitizer in the KeratinoSens assay if the reporter gene expression is induced above a fold of 1.5 (EC 1.5) at concentrations below 1000 uM (or 200 ug/mL) with no observed reduction in cell viability greater than 30%. Increased reporter gene expression in cells with less than 70% cell viability could be due to cell stress rather than a potential skin sensitizing effect.

Relative gene expression, EC 1.5, relative cell viability and IC30 are calculated as in OECD TG 442D.
Key result
Run / experiment:
other: Experiment #1
Parameter:
other: EC 1.5 (%)
Remarks:
Effective concentration at 1.5 fold increase
Value:
0.001
Vehicle controls validity:
valid
Negative controls validity:
valid
Positive controls validity:
valid
Remarks on result:
positive indication of skin sensitisation
Key result
Run / experiment:
other: Experiment #2
Parameter:
other: EC 1.5 (%)
Remarks:
Effective concentration at 1.5 fold increase
Value:
0.005
Vehicle controls validity:
valid
Negative controls validity:
valid
Positive controls validity:
valid
Remarks on result:
no indication of skin sensitisation
Key result
Run / experiment:
other: Experiment #3
Parameter:
other: EC 1.5 (%)
Remarks:
Effective concentration at 1.5 fold increase
Value:
0.005
Vehicle controls validity:
valid
Negative controls validity:
valid
Positive controls validity:
valid
Remarks on result:
no indication of skin sensitisation
Key result
Run / experiment:
other: Experiment #1
Parameter:
other: MR Imax
Remarks:
Maximum fold response of Keratinosens
Value:
2.24
Vehicle controls validity:
valid
Negative controls validity:
valid
Positive controls validity:
valid
Remarks on result:
positive indication of skin sensitisation
Key result
Run / experiment:
other: Experiment #2
Parameter:
other: MR / Imax
Remarks:
Maximum fold response of Keratinosens
Value:
0
Vehicle controls validity:
valid
Negative controls validity:
valid
Positive controls validity:
valid
Remarks on result:
no indication of skin sensitisation
Key result
Run / experiment:
other: Experiment #3
Parameter:
other: MR / Imax
Remarks:
Maximum fold response of Keratinosens
Value:
0
Vehicle controls validity:
valid
Negative controls validity:
valid
Positive controls validity:
valid
Remarks on result:
no indication of skin sensitisation
Other effects / acceptance of results:
OTHER EFFECTS:
- Cell Viability: IC30 (%) Concentration at 30% loss of cell viability; MR (%) Maximum % response in cell viability loss; MRC (%) Concentration at maximum response
Experiment #1: IC30 = 0.00505%; MR = 100%; MRC = 0.02 %
Experiemnt #2: IC30 = 0.00538%; MR = 100%; MRC = 0.02%
Expeirment #3: IC30 = 0.00809%; MR = 100%; MRC = 0.02%

DEMONSTRATION OF TECHNICAL PROFICIENCY:

ACCEPTANCE OF RESULTS:
- Acceptance criteria met for vehihcle control: The avergae coefficient of variation of the luminescens reading for the solvent/vehicle (DMSO) control should be below 20% in each replicate experiment
- Acceptance criteria met for positive control: The luciferase activity induction obtained for cinnamic aldehyde should be staitically significant above the threshold of 1.5 in at least one of the tested concentrations (4 to 64 uM). Second, the EC 1.5 value shoudl be within two standar deviations of the historical mean of the testing facility (or between 7 uM and 30 uM based on the validation dataset). In addition, the average induction in the three replicates for cinnamic aldehyde at 64 uM should be between 2 and 8.
- Acceptance criteria met for variability between replicate measurements: not applicable
- Range of historical values if different from the ones specified in the test guideline: not specified
Interpretation of results:
other: Not sensitizing
Conclusions:
Hydrazine Carboximidamide, 2-((2-hydroxyphenyl)methylene)-, reaction products with 2 undecanone did not produce evidence of keratinocyte activation in the in-vitro KeratinoSens assay. These findings do not meet OECD testing criteria necessary for a positive prediction. However, this specific study only gives information on one key event of the skin sensitization AOP and should be assessed with other information within a defined approach or weight of evidence.
Executive summary:

The potential for Hydrazine Carboximidamide, 2-((2-hydroxyphenyl)methylene)-, reaction products with 2 undecanone to activate keratinocytes was evaluated in the in-vitro KeratinoSens assay. The induction of luciferase gene expression (Keap1-Nrf2-ARE pathway) alongside cell viability following 48 hours of treatment with test compound was measured in three replicates.

In two out of three replicates, the test substance produced EC 1.5 values greater than the concentration producing 30% cell viability loss indicating a negative response in the assay. These findings do not meet OECD testing criteria necessary for a positive prediction. However, this study only gives information on one key event of the skin sensitization AOP and should be assessed with other information within a defined approach.

Endpoint conclusion
Endpoint conclusion:
adverse effect observed (sensitising)

Respiratory sensitisation

Endpoint conclusion
Endpoint conclusion:
no study available
Additional information:

Since under REACH, in-vitro studies are sufficient for compliance with Annexes VII, no key in-vivo study has been conducted. A weight of evidence approach was applied to determine the skin sensitization potential of Hydrazine Carboximidamide, 2-((2-hydroxyphenyl)methylene)-, reaction products with 2 undecanone using both in-vitro and non-testing methods.

 

No existing human or in-vivo study data on skin sensitization was available for inclusion in the weight of evidence.

 

Due to a data gap in skin sensitization, and the presence of a hydrazine functional group, Hydrazine Carboximidamide, 2-((2-hydroxyphenyl)methylene)-, reaction products with 2 undecanone was tested for skin sensitization potential using the in-vitro assays corresponding to the Skin Sensitization adverse outcome pathway. The three in-vitro assays used in the “2 out of 3” defined approach target different key events of the skin sensitization adverse outcome pathway: key event #1 is the assessment of protein binding in chemico (OECD 442 C: DPRA); key event #2, the trigger of an antioxidant/inflammatory response in keratinocytes (OECD 442D: KeratinoSens) and; key event #3, the activation of dendritic cells (OECD 442E: h-CLAT). Per OECD TG 442C, the DPRA is not applicable to UVCBs due to the need for a defined molar ratio between test substance and cysteine/lysine peptide.

 

In the Keratinosens assay, Hydrazine Carboximidamide, 2-((2-hydroxyphenyl)methylene)-, reaction products with 2 undecanone produced 2 negative outcomes out of 3 replicates for an overall negative Keratinosens prediction. The study was assigned a Klimisch score of 2; however some uncertainty as to whether the substance falls within the applicability domain of the assay exists. The LogP of this UVCB ranges from -0.08 to 5.2, with the majority of peaks observed in the higher end of the range. Additionally, based on the ESAC opinion in the EURL ECVAM recommendations of the KeratinosensTM assay, it is more likely to under predict or not reliably identify chemicals showing a low to moderate skin sensitization potency or those sensitising chemicals with selective reactivity towards other nucleophiles (e.g. amine reactive chemicals preferentially reacting with lysine residues), thereby leading to a higher rate of false negatives. The variable results of the assay are informed by the range of QSAR predictions for this UVCB.

In the human cell line activate test (h-CLAT, key event #3), a positive result was obtained for CD54 (RFI≥200%) in two out of three replicates which resulted in an overall positive h-CLAT prediction. No positive response was observed for CD86 in any replicate at any dose tested. The study was given a Klimisch score of 1 and is capable of discriminating sensitizers from non-sensitizers.

 

Consequently, one negative and one positive result was obtained in the Keratinosens and h-CLAT assays respectively. Following the "2 out of 3" in-vitro defined approach, a conclusion on the skin sensitization potential could not be determined for Hydrazine Carboximidamide, 2-((2-hydroxyphenyl)methylene)-, reaction products with 2 undecanone. Since the DPRA in-vitro assay is not applicable to UVCBs, in-silico (Q)SAR modeling was conducted to provide additional information on Key event #1: protein reactivity in order to support a weight of evidence approach.

 

A (Q)SAR prediction for skin sensitization was generated using the Skin Sensitization with autoxidation v.20.24 model of the OASIS TIMES v.2.27.17 software. Hypothetical potential structures were generated based on the chemistry of the reactants and manufacturing process. The prediction for hypothetical structures within this UVCB substance ranged from non-sensitizing to sensitizing. Approximately 33% (5/15) of the hypothetical structures were considered positive by their very nature or due to autoxidation transformations. The (Q)SAR prediction is given a Klimisch score of 2 (reliable with restrictions) as the results are derived from a valid (Q)SAR model with adequate and reliable documentation/justification but not (completely) falling into the applicability domain. The (Q)SAR model is considered capable of predicting skin sensitization. This data is consistent with the positive h-CLAT in-vitro skin sensitization data and supports the variability observed in the individual replicates within each in-vitro test. The (Q)SAR prediction suggests the potential for skin sensitization but is based on hypothetical potential structures and due to the chemical falling outside of the structural applicability domain, it is given a lower weight in the final evaluation.

 

Overall Conclusion:

In-vitro testing for skin sensitization produced variable results with some positive and some negative results indicating this substance may have very weak sensitizing properties. Although outside the applicability domain for the QSAR model, the predictions support the variable nature of the in-vitro testing results. Since no new in-vivo testing is considered at Annex VII, the overall weight of evidence is considered to support the classification for skin sensitization (Category 1) as a precautionary principle. Based on the available data, no evaluation of potency and therefore subcategorization is possible.

Justification for classification or non-classification

Hydrazine Carboximidamide, 2-((2-hydroxyphenyl)methylene)-, reaction products with 2 undecanone was evaluated for its skin sensitization potential using a weight of evidence approach including in-vitro and non-testing methods. Since no new in-vivo testing is considered at Annex VII, the overall weight of evidence is considered to support the classification for skin sensitization (Category 1) under the Regulation (EC) 1272/2008 on classification, labeling and packaging of substances and mixtures (CLP).