Butan-1-ol

Endpoint summary

Description of key information

The results of a LLNA study (in vivo) showed that the test item does not have a sensitizing effect on the skin under the test conditions chosen. In addition, the test substance is not peptide reactive and shows no activation of keratinocytes or dendritic cells.

Furthermore, QSAR OASIS TIMES model for skin sensitization (TIMES-SS) and QSAR Toolbox predicted for n-butanol to be a non-sensitizer.

Key value for chemical safety assessment

Skin sensitisation

Link to relevant study records

Reference

Reference 1

Endpoint:

skin sensitisation: in vivo (LLNA)

Type of information:

experimental study

Adequacy of study:

weight of evidence

Reliability:

1 (reliable without restriction)

Rationale for reliability incl. deficiencies:

comparable to guideline study

Qualifier:

equivalent or similar to guideline

Guideline:

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

GLP compliance:

not specified

Type of study:

mouse local lymph node assay (LLNA)

Species:

mouse

Strain:

other: CBA/J mice strain and CBA/Ca strain

Sex:

female

Details on test animals and environmental conditions:

TEST ANIMALS
- Source: CBA/J strain mice:Harlan Sprague Dawley, Inc., Indianapolis, IN or Jackson
Laboratories, Bar Harbor, ME; female
CBA/Ca strain mice: Harlan Olac Bicester, Oxfordshire, UK
- Females (if applicable) nulliparous and non-pregnant: [yes/no/not specified] not specified
- Age at study initiation:6-12 weeks

Vehicle:

other: distilled water

Concentration:

5%, 10% and 20% (v/v) in distilled water

No. of animals per dose:

n=5 (Laboratory A) or n=4 (Laboratory B and C)

Details on study design:

- groups of mice were treated 1x a day for 3 consecutive days on the dorsum of both ears with 25 µL of
1 of 3 concentrations of test material or with vehicle
- 5 days after initial treatment, all mice were injected intravenously, via the tail vein, with 250 µL PBS
containing 20 mCi of 3H-methylthymidine (3H-TdR; specific activity 5.0 Ci/mmol for Laboratory A, 2.0 Ci/mmol for Laboratories B and C, respectively).
- 5 h later, mice were euthanised and draining auricular lymph nodes were removed and pooled for each
individual mouse (Laboratory A) or for each experimental group (Laboratories B and C)
- single cell suspensions were prepared
- samples were centrifuged, resuspended in 1 mL 5% TCA and transferred to 10 mL of
scintillation cocktail
- 3H-TdR incorporation was measured by b-scintillation counting and expressed
as disintegrations per min (dpm) per individual mouse (Laboratory A) or as dpm per node for each experimental group (Laboratories B and C)

Stimulation indices (SI) for each experimental group were determined as the increase in 3H-TdR incorporation relative to concurrent vehicle treated control group. Positive: 3-fold or greater increase in proliferation, compared with the concurrent vehicle control, obtained at 1 or more test concentrations.

Key result

Parameter:

SI

Value:

1

Test group / Remarks:

vehicle water

Key result

Parameter:

SI

Value:

1.6

Test group / Remarks:

5% (v/v)

Key result

Parameter:

SI

Value:

1.2

Test group / Remarks:

10% (v/v)

Key result

Parameter:

SI

Value:

1.4

Test group / Remarks:

20% (v/v)

Cellular proliferation data / Observations:

vehicle water: 366 ± 44 mean dpm (± SEM)
5% (v/v) 1-butanol: 598 ± 157 mean dpm (± SEM)
10% (v/v) 1-butanol: 451 ± 17 mean dpm (± SEM)
20% (v/v) 1-butanol: 530 ± 91 mean dpm (± SEM)

Interpretation of results:

GHS criteria not met

Reference 2

Endpoint:

skin sensitisation: in chemico

Type of information:

experimental study

Adequacy of study:

weight of evidence

Reliability:

2 (reliable with restrictions)

Rationale for reliability incl. deficiencies:

guideline study without detailed documentation

Qualifier:

equivalent or similar to guideline

Guideline:

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

GLP compliance:

not specified

Remarks:

no data regarding GLP complicance provided

Type of study:

direct peptide reactivity assay (DPRA)

Specific details on test material used for the study:

SOURCE OF TEST MATERIAL
- Manufacturer: Sigma-Aldrich, Taufkirchen, Germany
- batch No.of test material: 47296KMV

Details on the study design:

Synthetic peptides:
Cysteine- (C-) containing peptide: Ac-RFAACAA-COOH (MW=751.9 g/mol)
Lysine- (K-) containing peptide: Ac-RFAAKAA-COOH (MW=776.2 g/mol)

Controls:
Positive control (PC): p-Benzoquinone, puriss. (CAS 106-51-4)
Negative control (NC): Vehicle for n-Butanol = acetonitrile

Test substance preparation:
The test substance was prepared as a 100 mM stock solution in acetonitrile just prior to incubation with
the synthetic peptides. Three samples of the test substance were incubated with each peptide in ratios of 1:10 (for C-peptide) or 1:50 (for K-peptide). Additionally triplicates of the concurrent vehicle control (= NC) were incubated with the peptides.

The peptide depletion of test-substance incubated samples was compared to the peptide depletion of the NC samples and expressed as relative peptide depletion. For the test substance the mean peptide depletion as average of C- and K-peptide depletion is calculated and used for evaluation of the chemical reactivity

Evaluation of results:
Chemical reactivity was determined by mean peptide depletion and was rated as high, moderate, low, or minimal:
Mean peptide depletion [%] Reactivity
> 42.47 high reactivity
> 22.62 < 42.47 moderate reactivity
> 6.38 < 22.62 low reactivity
< 6.38 minimal reactivity

Species:

other: synthetic peptides (Cysteine- (C-) containing peptide: Ac-RFAACAA-COOH; Lysine- (K-) containing peptide: Ac-RFAAKAA-COOH)

Key result

Run / experiment:

mean

Parameter:

other: combined peptide depletion [%]

Value:

-0.3

Vehicle controls validity:

valid

Positive controls validity:

valid

Remarks on result:

no indication of skin sensitisation

Parameter:

other: cystein-peptide depletion [%]

Value:

0.7

Vehicle controls validity:

valid

Positive controls validity:

valid

Remarks on result:

no indication of skin sensitisation

Parameter:

other: lysine-peptide depletion [%]

Value:

-1.3

Vehicle controls validity:

valid

Positive controls validity:

valid

Remarks on result:

no indication of skin sensitisation

Interpretation of results:

GHS criteria not met

Reference 3

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:

comparable to guideline study with acceptable restrictions

Qualifier:

equivalent or similar to guideline

Guideline:

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

GLP compliance:

not specified

Remarks:

no data regarding GLP complicance provided

Type of study:

activation of keratinocytes

Details on the study design:

Cell line used:
Wild-type HaCaT cells were maintained in Dulbecco's modified Eagle's medium containing glutamax (Gibco/Invitrogen) supplemented
with 9% fetal calf serum at 37 °C in the presence of 5% CO2. The medium for the stable engineered cell line KeratinoSens was
supplemented with 500 μg/mL G418.

Preparation of test chemicals:
Test chemicals were dissolved in DMSO at a concentration of 200 mM and serially diluted in DMSO to obtain 12 final
concentrations ranging from 0.1 mM to 200 mM. DMSO solutions were diluted 25-fold in culture medium containing 1% FCS.

Main test:
KeratinoSens cells were seeded in 96-well plates at a density of 10000 cells per well.
50 μL of the 1% FCS medium containing the different dilutions of the DMSO solutions was added to wells for 48h
Each chemical was tested in triplicate at all the 12 concentrations. As a control tert-butyl-hydroquinone was always
included in each test plate, and each plate contained six control wells with cells and solvent.

Cell viability assay MTT:
For the cell viability assay, 27 μL of a MTT solution (5 mg/ml in DPBS) was added to each well. After 4 h
incubation, the medium was removed and 200 μL of a 10% SDS solution was added to each well. After the cells have
dissolved completely, the absorption at 600 nm was determined for each well.

Luciferase assay
After incubation, medium was removed and cells were washed once with PBS. To each well, 20 μL
of passive lysis buffer was added and the cells were incubated for 20 min at RT. Plates were then read in a
Promega Glomax luminometer.

Evaluation critaria:
The average maximal induction of gene activity and the average concentration inducing significantly
enhanced gene activity >50% above control values (EC1.50) were determined. The latter calculations were
performed with linear extrapolation from the values above and below the induction
threshold (as for the EC3 value determination in the LLNA). Each independent repetition was statistically evaluated.
A chemical was rated positive, if it statistically significantly induced the luciferase activity more than 50% above control
values at any of the tested concentrations in both independent repetitions. For chemicals with significant induction in only
one repetition, two further repetitions were made. These chemicals were rated positive if the luciferase induction was statistically
significant in at least 3 out of the total 4 independent repetitions. In addition, also the EC2 and EC3 for 100% and 200%
enhanced luciferase expression were calculated with linear extrapolation and added as additional information.

Key result

Parameter:

other: EC1.50 (concentration resulting in a 1.5-fold luciferase induction)

Remarks on result:

other: no significant induction above threshold

Interpretation of results:

GHS criteria not met

Reference 4

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:

comparable to guideline study with acceptable restrictions

Qualifier:

equivalent or similar to guideline

Guideline:

other: OECD TG 442E In Vitro skin Sensitisation:human Cell Line Activation Test (h-CLAT)

GLP compliance:

not specified

Remarks:

no data regarding GLP complicance provided

Type of study:

activation of dendritic cells

Specific details on test material used for the study:

Source: Sigma-Aldrich

Details on the study design:

Cell line used:
THP-1 cells, The human monocytic leukemia cell line was obtained from “American Type Culture Collection, Manassas, USA”
Technical material and conditions:
Culture medium: RPMI 1640+ 10% FBS inactivated + 1% antibiotic/antimycotic + 0.05 mM 2-Mercaptoethanol

Test substance preparation:
The test chemicals were dissolved in saline or DMSO. The final DMSO concentration in the assay medium did not exceed 0.2%.

Main test and staining:
THP-1 cells were incubated for 24h with test chemicals at eight concentrations of a 1.2 -fold serial dilution. Then, cells were resuspended with staining buffer containing 0.01% globlins Cohn fraction II/III for the Fe receptor-blocking and incubated for 15 min at 4°C. Cells were stained for 30 min at 4°C with FITC-conjugated monoclonal antibodies:mouse IgG1,anti-human CD54 and anti-human CD86.Fluorescence intensity was analyzed by flow cytometry.

Evaluation of results:
If the relative fluorescene intensity of CD86 and CD54 was greater than 150% or 200% at any dose in at least two out of three experiments, the test material was judged as a sensitizer

Key result

Parameter:

other: CD86 and CD54 activity

Remarks on result:

other: no fluorescence activity was measured

Interpretation of results:

GHS criteria not met

Reference 5

Endpoint:

skin sensitisation: in chemico

Type of information:

experimental study

Adequacy of study:

weight of evidence

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))

Deviations:

yes

Remarks:

three concentrations of chemicals were tested

GLP compliance:

not specified

Remarks:

no data regarding GLP complicance provided

Type of study:

direct peptide reactivity assay (DPRA)

Details on the study design:

Synthetic peptides:
Cysteine- (C-) containing peptide: Ac-RFAACAA-COOH (MW=751.9 g/mol)
Lysine- (K-) containing peptide: Ac-RFAAKAA-COOH (MW=776.2 g/mol)

Controls:
Positive control (PC): EGDMA (Ethylene glykol dimethacrylate, 98.1% purity), Citral
Negative control (NC): Vehicle for n-Butanol and EGDMA = acetonitrile

Test substance preparation:
The test substance was prepared as a 100 mM, 10 mM and 1 mM stock solution in acetonitrile
just prior to incubation with the synthetic peptides.

The ratio of peptide and chemical in the samples was as follows:
100 mM ( 1:10 and 1:50 for C-containing peptide and K -containing peptide, respectively)
10 mM ( 1:1 and 1:5 or C-containing peptide and K -containing peptide, respectively)
1 mM (10:1 and 2:1 or C-containing peptide and K -containing peptide, respectively)

2 replicates were tested for each concentration in a single run with the exception of citral,
which was tested in 9 runs and ethylene glykol dimethacrylate, which was
tested in 6 runs. Further, co-elution controls were analyzed in order to detect possible
interference of the test substance with the peptides. These samples consisted of the
test substance, vehicle and the respective peptide buffer but without peptide.
Moreover the samples were additionally analyzed by measuring UV absorbance at 258 nm
and the area ratio 220 nm/ 258 nm was calculated as a measure of peak purity.

Evaluation of results:
In the standard protocol of the DPRA the mean peptide depletion [%] caused by a 100 mM
concentration is used to determine the chemical reactivity, rated as high, moderate, low, or
minimal.
A mean peptide depletion of > 42.47 % is regarded as high reactivity and positive for peptide depletion
(indication for sensitization potential). A moderately reactive test substance (22.62 % < mean peptide
depletion ≤ 42.47 %) and a test substance of low reactivity (6.38% < mean peptide depletion ≤ 22.62
%) are regarded as positive for peptide depletion (indication for sensitization potential). A mean peptide
depletion of ≤ 6.38 % is a minimal to no reactivity and negative for peptide depletion
(no indication for sensitization potential). For each chemical the mean peptide depletion as average
of C- and K-peptide depletion was calculated for each concentration. When possible, an effective
concentration (EC 6.38%) was calculated by linear regression, giving the concentration of chemical
required to cause 6.38% peptide depletion (mean of C- and K-peptide).

Species:

other: synthetic peptides (Cysteine-(C-) containing peptide: Ac-RFAACAA-COOH; Lysine-(K-) containing peptide: Ac-RFAAKAA-COOH)

Positive control results:

For the PC EGDMA no historic data was available for 100mM. However, the historic data for 50 mM (61% cysteine depletion and 13% lysine depletion)
fit well to the PC-data of the present study.

Key result

Run / experiment:

mean

Parameter:

other: combined peptide depletion [%]

Remarks:

for 100mM

Value:

0.5

Negative controls validity:

valid

Positive controls validity:

valid

Remarks:

55 %

Remarks on result:

no indication of skin sensitisation

Parameter:

other: cystein peptide depletion [%]/ for 100mM

Value:

-0.39

Negative controls validity:

valid

Positive controls validity:

valid

Remarks:

85%

Remarks on result:

no indication of skin sensitisation

Parameter:

other: lysine peptide depletion [%]/ for 100mM

Value:

1

Negative controls validity:

valid

Positive controls validity:

valid

Remarks:

25%

Remarks on result:

no indication of skin sensitisation

Other effects / acceptance of results:

No co-elution of the test substance and peptides occurred.

Interpretation of results:

GHS criteria not met

Reference 6

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:

comparable to guideline study with acceptable restrictions

Qualifier:

equivalent or similar to guideline

Guideline:

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

Qualifier:

equivalent or similar to guideline

Guideline:

other: OECD 442E In Vitro Skin Sensitisation:human Cell line Activation test (h-CLAT)

Qualifier:

equivalent or similar to guideline

Guideline:

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

Guideline:

other: Modified myeloid U937 skin sensitisation assay

Principles of method if other than guideline:

Principle of LuSens Assay:
Identification of keratinocyte activating substances with the transgenic keratinocyte cell line Lu-Sens
derived from HaCaT cells. lt employs the reporter gene for luciferase under the control of an antioxidant response element
and hence monitors Nrf-2 transcription factor activity. The endpoint measurement is the up-regulation of the luciferase activity after
48 hour incubation with test substances. This up-regulation is an indicator for the activation of the Keap1/Nrf2/ARE signaling pathway
(Ade et al. 2009, Natsch 2012, Natsch & Emter 2008, Vandebriel et al. 2010).

Principle of Modified myeloid U937 skin sensitisation assay:
Measurement of CD 86 expression as marker for stimulation of human dentritic cells.

GLP compliance:

not specified

Remarks:

no data regarding GLP complicance provided

Type of study:

other: Direct Peptide Reactivity Assay (DPRA), LuSens assay, KeratinoSens Assay, Modified myeloid U937 skin sensitization test (mMUSST), Human cell line activation test (h-CLAT) in silico: OECD QSAR Toolbox Version 2.0 (protein binding module)

Specific details on test material used for the study:

SOURCE OF TEST MATERIAL
- Source of test material: Sigma-Aldrich

Details on the study design:

LuSens assay:
- LuSens cells (HaCaT cells with reporter gene for luciferase) were grown for 24h in 96-well plates prior substance treatment
- stock solutions of substances were prepared by dissolving in distilled water or DMSO (final 200mM), further dilution
in cell culture medium
- dilutions ranging from 1-2000 µM were tested, incubation time: 48h
- Positive control: Cinnamic aldehyde (Sigma-Aldrich) 2-32 µM
- luciferase activity was determined using SteadyGlo (Promega)
- cytotoxicity was tested using MTT-assay

KeratinoSens Assay:
- KeratinoSens cells were grown for 24h in 96 well plates prior treatment
- stock solutions of substances were prepared by dissolving in distilled water or DMSO (final 200mM), further dilution in cell culture medium
- dilutions ranging from 1-2000 µM were tested, incubation time:48h
- Positive control: Cinnamic aldehyde (Sigma-Aldrich) 4-64 µM
- luciferase activity was determined using SteadyGlo (Promega) and compared to vehicle controls
- cytotoxicity was tested with MTT-assay

Modified myeloid U937 skin sensitization assay:
- U937 cells (human histiocytic lymphoma cell line) were grown for 24h in 96-well plates prior substance treatment
- substances were dissolved either in medium or in DMSO (DMSO-dissolved substances were further diluted in medium)
- cells were exposed for 48h to 12 concentrations obtained in a 2-fold dilution series starting at 2000 µg/mL for solid test
substances or 1000 µg/mL for liquid test substances
- cells were labeled with IgG-FITC or anti-CD86-FITC antibodies and flow cytometry was performed

Human cell line activation test:
- THP-1 cells were seeded in 24-well plates
- substances were dissolved either in medium or in DMSO (DMSO-dissolved substances were further diluted in medium) and
incubated for 24h on cells
- each substance was tested in eight concentrations
- cells were labeled with IgG1-FITC , anti-CD54-FITC or anti-CD86-FITC and flow cytometry was performed

Details on the study design:

Direkt Peptide Reactivity Assay (DPRA):
- Test substance n-Butanol was dissolved in acetonitrile (Sigma-Aldrich) to prepare 100mM solution
(freshly prepared prior to use)
- cysteine-model peptide (ac-RFAACAA-COOH)/lysine-model peptide (Ac-RFAAKAA-COOH)
- peptide/test sample solutions were prepared in a ratio 1:4:15 (v/v/v) substance:acetonitrile:cysteine peptide or in
a ratio 1:3 (v/v) substance:lysine peptide and incubated for 24 h in the dark at room temperature
- analyses of free peptide was performed by RP-HPLC with UV detection at 220 nm

Key result

Run / experiment:

other: DPRA

Parameter:

other: mean peptide depletion

Value:

-0.3

Vehicle controls validity:

valid

Negative controls validity:

valid

Positive controls validity:

valid

Key result

Run / experiment:

other: LuSens

Remarks on result:

other: below threshold

Key result

Run / experiment:

other: KeratinoSens

Remarks on result:

other: below threshold

Key result

Run / experiment:

other: OECD Toolbox v2.0

Remarks on result:

other: no binding

Key result

Run / experiment:

other: mMUSST-CD86

Remarks on result:

other: below threshold

Key result

Run / experiment:

other: h-CLAT-CD86

Parameter:

other: EC1.5 in µg/mL

Value:

921

Remarks on result:

other: n-Butanol was rated false positive (comparison to LLNA)

Interpretation of results:

GHS criteria not met

Reference 7

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 and falling into its applicability domain, with adequate and reliable documentation / justification

Justification for type of information:

Please refer to the QMRF and QPRF files provided under the section attached background material.

Qualifier:

according to guideline

Guideline:

other: REACH guidance on QSARs R.6, May/July 2008

Principles of method if other than guideline:

TIMES-SS 2.27.19 - Skin sensitization v. 21.26 with autoxidation (structure-toxicity and structure-metabolism relationships)

GLP compliance:

no

Type of study:

other: calculation QSAR

Remarks on result:

no indication of skin sensitisation based on QSAR/QSPR prediction

TIMES-SS model aims to encode structure toxicity and structure metabolism relationships through a number of transformations simulating skin metabolism and interaction of the generated reactive metabolites with skin proteins. The skin metabolism simulator mimics metabolism using 2D structural information. The autoxidation (abiotic oxidation) of chemicals is also accounted for. A training set of diverse chemicals was compiled and their skin sensitization potency assigned to one of three classes. These three classes were Strong, Weak or Non-sensitizing. The skin sensitization model was built as a composite of the following sub models: 1. Skin metabolism Simulator: This mimics the metabolic fate of parent chemical controlled by skin enzymes and thus the potential formation of protein adducts with reactive agents. 2D structural information of parent chemicals is used to model metabolism. Metabolic pathways are generated based on a set of hierarchically ordered principal transformations including spontaneous reactions, enzyme-catalyzed Phase I and Phase II drug metabolism reactions, and reactions with protein nucleophiles. The formation of macromolecular immunogens was used to identify probable structural alerts in parent chemicals or their metabolites. 2. COREPA (COmmon Pattern Recognition approach) 3D QSARs for intrinsic reactivity of compounds having substructures associated with activity. These models depend on both the structural alert and the rate of skin sensitization. Steric effects around the active site, molecular size, shape, solubility, lipophilicity and electronic properties are taken into account. These models generally may involve combinations of molecular parameters or descriptors, which trigger (“fire”) the alerting group. A quantitative structure-activity relationship (QSAR) system for estimating skin sensitization potency has been developed which incorporates skin metabolism and considers the potential of parent chemicals and/or their activated metabolites to react with skin proteins. The autoxidation (abiotic oxidation) of chemicals is also accounted for. A training set of diverse chemicals was compiled and their skin sensitization potency assigned to one of three classes. These three classes were Strong, Weak or Non-sensitizing.

 The applicability domain of TIMES-SS model consists of the following layers:

1. General parametric requirements - includes ranges of variation of log KOW and MW. It specifies in the domain only those chemicals that fall in the range of variation of the MW (from 30 to 737 Da, in this study) and log Kow (from -13.2 to 15.4, in this study) defined on the bases of the correctly predicted training set chemicals. This layer of the domain is applied only on parent chemicals.

2. Structural domain - it is represented by the list of atom - centered fragments extracted from the chemicals in the training set. The training chemicals were split into two subsets: chemicals correctly predicted by the model and incorrectly predicted chemicals. These two subsets of chemicals were used to extract characteristics determining the "good" and "bad" space of the domain. Extracted characteristics were split into three categories: unique characteristics of correct and incorrect chemicals (presented only in one of the subsets) and fuzzy characteristics presented in both subsets of chemicals. The target structure is also partitioned into atom-centered fragments and when they present in the list of extracted atom-centered fragments from the training set chemicals and satisfy the accepted thresholds the chemical is categorized as belonging to the structural domain. The default thresholds for classifying of chemicals to the structural domain of the current skin sensitization model are:

·        All extracted fragments to belong to the "good" domain ("Correct" = 100%)

·        All fuzzy fragments are considered as part of the "good" domain

·        No fragments belonging to "bad" domain ("Incorrect" = 0%)

·        No unique fragment ("Unknown" = 0%) Structural domain is applied on parent chemicals, only.

3. Mechanistic domain - in SS model it includes:

·        Interpolation space:

This stage of the applicability domain of the model holds only for chemicals for which an additional COREPA model is required. It estimates the position of the target chemicals in the population density plot built in the parametric space defined by the explanatory variables of the model by making use the training set chemicals. The accepted threshold of population density in the current study is 10%. Chemicals with values below 10% are "Out of domain". "N/A" is assigned when this type of sub-domain is not relevant to the structure and will be not accounted in the total domain. "Unknown" is referred for the cases when some parameters could not be calculated by any reason or for chemicals with equivocal predictions (not reaching the probability threshold of the COREPA model and reported in TIMES as Can't predict). The mechanistic domain is applied on the parent structures and on their metabolites. In order to belong to the model domain a target structure must meet the requirements of all the domain layers.

The current skin sensitization model was developed using a dataset of 875 chemicals tested by Local Lymph Node Assay (LLNA), Guinea Pig Maximization Test (GPMT) and chemicals from the BfR list. For 875 chemicals, the TIMES-SS model was able to predict correctly 90% of the strong sensitizers, 55% of the weak sensitizers and 77% of the non-sensitizers, i.e., an overall performance of 78%. The QSAR program calculated a negative sensitization potential of the test substance. The substance fulfills the general properties requirements.

Interpretation of results:

GHS criteria not met

Reference 8

Endpoint:

skin sensitisation, other

Type of information:

(Q)SAR

Adequacy of study:

other information

Reliability:

4 (not assignable)

Rationale for reliability incl. deficiencies:

results derived from a valid (Q)SAR model, but not (completely) falling into its applicability domain, and documentation / justification is limited

Justification for type of information:

Please refer to the attached full study report.

Principles of method if other than guideline:

Toxicity of the target chemical is predicted from category members using read-across based on 5
values from 5 nearest neighbours compared by prediction descriptors. Category members are
single chemicals or mixtures and are selected based on the profile of the target chemical . Only chemicals
having experimental data are listed in the category.The target chemical DOES NOT FALL within applicability domain of the prediction.
The data used for calculating the current prediction is taken from 7 experimental values selected from the
following database(s):
1. ECHA CHEM
2. Skin Sensitization

GLP compliance:

no

Type of study:

other: QSAR Toolbox

Remarks on result:

no indication of skin sensitisation based on QSAR/QSPR prediction

The substance is considered a non sensitizer based on read across to the following substances:

CAS Number	Substance Name
26184 -62 -3	2 -pentanol
71 -41 -0	1 -pentanol
111 -27 -3	1 -hexanol
111 -70 -6	1 -heptanol
123 -96 -6	2 -octanol
111 -87 -5	1 -octanol
143 -08 -8	1 -nonanol
85711 -26 -8	alcohols,c9 -11, c2 -12, c9 -11 branched an linear
112 -30 -1	1 -decanol
66455 -17 -2	alcohols,c9 -11, c7 -c9
1653 -30 -1	2 -undecanol
112 -42 -5	1 -undecanol
112 -53 -8	1 -dodecanol
75782 -86 -4	alcohols, c12 -13
112 -72 -1	myristyl alcohol
75782 -87 -5	alcohols, c14 -15
629 -76 -5	1 -pentadecanol

Profiling results for the target substance:

DNA binding by OECD: No alert found

Est rogen Receptor Binding: Non binder, non cyclic structure

OECD HPV Chemical Categories: Not categorized

Protein binding by OECD: No alert found

Protein binding potency: Not possible to classify according to these rules (GSH)

Superfragments: No superfragment

Toxic hazard classification by Cramer (original): Low (Class I)

US-EPA New Chemical Categories: Neutral Organics

Interpretation of results:

GHS criteria not met

Endpoint conclusion

Endpoint conclusion:

no adverse effect observed (not sensitising)

Additional information:

A LLNA assay was performed equivalent to OECD test guideline 429 (Ryan CA et al. 2000). The assay simulates the induction phase for skin sensitization in mice and determines the response of the auricular lymph nodes on repeated application of the test substance to the dorsal skin of the ears. Groups of 4 female CBA mice each were treated with 25 μL per ear of 5, 10 or 20 % of the test substance in distilled water to the dorsum of each ear for three consecutive days. A stimulation index (increase in 3HTdR incorporation compared to control values) of 1.6, 1.2, or 1.4 was recorded for the 5%, 10% and 20% concentrations of the test material, respectively. Due to an SI value < 3 the test material was identified as a non-sensitizer in the Murine Local Lymph Node Assay under the test conditions chosen.

In vitro studies covering three key steps of the adverse outcome pathway for skin sensitization as identified by the OECD (OECD Publication No.168; ENV/JM/MONO(2012)10) were performed. These study types have initially undergone in-house validation using 54 substances (Bauch et al., 2012 Regul Toxicol Pharmacol. 63: 489-504). Recently, a validation performed with 213 substances has been published (Urbisch et al. 2015 Regul Toxicol Pharmacol. 71: 337-351).

Based on the results of the in house validation (Bauch et al., 2012 Regul Toxicol Pharmacol. 63: 489-504) the predictive capacity of the evaluation scheme using DPRA (peptide reactivity), LuSens/KeratinoSens™ (keratinocyte activation) and (m)MUSST/h-CLAT (dendritic cell activation) is comparable to that of the local lymph node assay. This was confirmed in the validation study with more substances (Urbisch 2015): When compared to the sensitization potential of the substances in humans, the classification based on an evaluation scheme using results obtained from the DPRA, LuSens and mMUSST had a sensitivity of 90%, a specificity of 90% and an accuracy of 90%.

 In the evaluation scheme used here any two of the three test results determine the overall classification, i.e. any two positive test results drive the prediction of a sensitizer, while any two negative test results drive the prediction of a test substance to be a non-sensitizer (Bauch et al. 2012; Table 1). If two assays (DPRA ,LuSens or KeratinoSens, MUSST or h-CLAT) yield concordant results, the result of the third assay is not necessarily required to determine the overall outcome of the evaluation scheme.

DPRA	LuSens/KeratinoSens	MUSST/h-CLAT	test battery evaluation
positive	positive	positive	sensitizer
positive	positive	negative	sensitizer
positive	negative	positive	sensitizer
positive	negative	negative	non-sensitizer
negative	positive	positive	sensitizer
negative	positive	negative	non-sensitizer
negative	negative	positive	non-sensitizer
negative	negative	negative	non-sensitizer

Table 1: Decision matrix for combinations of DPRA, LuSens/KeratinoSens and MUSST/ h-CLAT assays.

Positive and negative controls were included in each experiment and confirmed the functionality and validity of the individual assays. The DPRA, the keratinocyte activation and the dendritic activation assay follow the procedures of the respective OECD testing guidelines (OECD 442C, D and E).

The test battery applicability is limited when testing substances insoluble in the commonly used vehicles and highly volatile substances.

Substances susceptible to base-catalyzed hydrolysis cannot be evaluated reliably for binding to lysine as the incubation is performed at pH 10.2. Also substances that interfere with the experimental measurements (e.g., co-elution with the peptide in the DPRA-assay) are not or only partially suitable for testing using in vitro methods. The substance under evaluation did not have any of the above mentioned limitations and the outcome of this assay is therefore considered adequate for hazard identification for the endpoint of skin sensitization.

The test substance is not peptide reactive, does not activate keratinocytes and does not activate dendritic cells. In accordance with the published evaluation scheme (Bauch et al., 2012 Regul Toxicol Pharmacol. 63: 489-504), butan-1 -ol is not considered to be a skin sensitizer.

In addition, QSAR OASIS TIMES model for skin sensitization (TIMES-SS) and QSAR Toolbox predicted for n-butanol to be a non-sensitizer.

In conclusion, no skin sensitization potential for butanol was observed in an in vivo test, an in vitro-test battery as well as in QSAR preditions.

Respiratory sensitisation

Endpoint conclusion

Endpoint conclusion:

no study available

Justification for classification or non-classification

Classification, Labelling, and Packaging Regulation (EC) No 1272/2008

The available experimental test data are reliable and suitable for classification purposes under Regulation (EC) No 1272/2008. As a result the substance is not considered to be classified as skin sensitizer under Regulation (EC) No 1272/2008, as amended for the ninth time in Regulation (EU) No 2016/1179.