2,2',4,4',6,6'-hexanitrostilbene

Endpoint summary

Description of key information

The approach predicts skin sensitisation hazard by sequential testing, in an undefined order, in the following three internationally accepted non-animal assays mapping to KE1-3:

- Direct Peptide Reactivity Assay (DPRA; OECD TG 442C; KE1) (2)

- KeratinoSens™ assay (In vitro Skin Sensitisation: ARE-Nrf2 Luciferase Test Method; OECD TG 442D; KE2)

- Human cell-line activation test (h-CLAT; OECD TG 442E; KE3).

The 2 out of 3 (2o3) Approach is used for the identification of the skin sensitisation hazard of a chemical without the use of animal testing.

Key value for chemical safety assessment

Skin sensitisation

Link to relevant study records

Reference

Reference 1

Endpoint:

skin sensitisation: in vitro

Type of information:

experimental study

Adequacy of study:

key study

Reliability:

1 (reliable without restriction)

Rationale for reliability incl. deficiencies:

guideline study

Qualifier:

according to guideline

Guideline:

OECD Guideline 442E (In Vitro Skin Sensitisation: human Cell Line Activation Test (h-CLAT))

GLP compliance:

yes

Type of study:

human Cell Line Activation Test (h-CLAT)

Specific details on test material used for the study:

Batch no. 18909-1
Composition 100%
Expiry date 27/2/2028

Details of test system:

THP-1 cell line [442E]

Details on the study design:

In total a pre-test and one valid experiment (2 runs) with a treatment period of 24 hours were
performed.
For the experiment the highest nominal applied concentration (10 µg/mL) was chosen based
on the results obtained in the pre-test. A geometric series (factor 1.2) of 7 dilutions was
prepared. Precipitation of the test item was not visible in none of the runs.
As solvent control for the test item, DMSO was used in a final concentration of 0.2 % in
culture medium.
As positive control, 2,4-dinitrochlorobenzene (DNCB, CAS n. 97-00-7, ≥ 99% purity) was
used.

Vehicle / solvent control:

DMSO

Positive control:

dinitrochlorobenzene (DNCB) [442E]

Run / experiment:

run/experiment 1

Parameter:

RFI CD86>200 [442E]

Cell viability:

≥ 50 %

Remarks on result:

no indication of skin sensitisation

Run / experiment:

run/experiment 2

Parameter:

RFI CD86>200 [442E]

Cell viability:

≥ 50 %

Remarks on result:

no indication of skin sensitisation

Run / experiment:

run/experiment 2

Parameter:

RFI CD54>150 [442E]

Cell viability:

≥ 50 %

Remarks on result:

no indication of skin sensitisation

Run / experiment:

run/experiment 1

Parameter:

RFI CD54>150 [442E]

Cell viability:

≥ 50 %

Remarks on result:

no indication of skin sensitisation

Other effects / acceptance of results:

In both runs the RFI of CD86 was not ≥ 150 % as well as the RFI of CD54 was not ≥ 200 % at
any tested concentration with cell viability ≥ 50 %.
Since the result of the two individual runs is negative, the test item is considered as “nega-
tive”.

Interpretation of results:

GHS criteria not met

Conclusions:

Under the experimental conditions of this study, the test item, HEXANITROSTILBENE, was
negative in the h-CLAT and is therefore considered not having the potential to activate den-
dritic cells and therefore not to up-regulate the cell surface marker (CD86 and CD54) ex-
pression of THP-1 cells.

Reference 2

Endpoint:

skin sensitisation: in vitro

Type of information:

experimental study

Adequacy of study:

key study

Reliability:

1 (reliable without restriction)

Rationale for reliability incl. deficiencies:

guideline study

Qualifier:

according to guideline

Guideline:

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

GLP compliance:

yes

Type of study:

activation of keratinocytes

Specific details on test material used for the study:

Batch no. 18909-1
Composition 100%
Expiry date 27/2/2028

Details of test system:

Keratinoses transgenic cell line [442D]

Details on the study design:

The assay included two cytotoxicity range finder tests (CRFT) and two experiments, con-
sisting of four independent repetitions (repetition I, II, III and IV) with a treatment period of
48 h. The first CRFT was performed to detect a potential cytotoxic effect of the test item,
however the cytotoxicity of the test item could not be reproduced in repetition I and II. The
second CRFT was performed to verify the result of the first CRFT. After detecting a technical
error, repetitions I and II were declared as invalid and were repeated (repetition III and IV).
The invalid repetitions I and II are not reported, all documentation is kept with the raw data
and will be archived at the GLP test facility.
In the experiment (repetition III and IV), the highest nominal applied concentration
(0.78 µg/mL) was chosen based on the results obtained in both CRFTs. A geometric series
(factor 1.2) of eleven dilutions thereof was prepared.
Precipitation of the test item was visible in both CRFTs in the six highest concentrations (50
µg/mL – 1.56 µg/mL).
The assay was performed in two independent repetitions. 12 concentrations of the test item
were evaluated. The exposure time was 48 h.
The following nominal concentrations of the test item were investigated in repetition III and
IV:
0.10 µg/mL, 0.13 µg/mL, 0.15 µg/mL, 0.18 µg/mL, 0.22 µg/mL, 0.26 µg/mL, 0.31 µg/mL,
0.38 µg/mL, 0.45 µg/mL, 0.54 µg/mL, 0.65 µg/mL, 0.78 µg/mL

Vehicle / solvent control:

DMSO

Negative control:

DL-Lactic acid

Positive control:

EGDMA (120 M) [442D]

Group:

test chemical

Run / experiment:

run/experiment 3

Cell viability:

110.2 at 0.10 ug/ml concentration
72.2 at 0.31 ug/ml concentration

Negative controls validity:

valid

Positive controls validity:

valid

Remarks on result:

positive indication of skin sensitisation

Conclusions:

Under the experimental conditions of this study, the test item, HEXANITROSTILBENE, was
positive in the LuSens assay and is therefore considered to have the potential to activate
the Nrf2 transcription factor (sensitizing potential)

Reference 3

Endpoint:

skin sensitisation: in chemico

Type of information:

experimental study

Adequacy of study:

key study

Reliability:

1 (reliable without restriction)

Rationale for reliability incl. deficiencies:

guideline study

Qualifier:

according to guideline

Guideline:

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

Qualifier:

according to guideline

Guideline:

EU Method B.59 (In Chemico Skin Sensitisation: Direct Peptide Reactivity Assay (DPRA)

GLP compliance:

yes

Type of study:

direct peptide reactivity assay (DPRA)

Specific details on test material used for the study:

Hexanitrostilbene 100%
Expiry date 27. Feb. 2028
Appearance Yellow crystals

Details of test system:

cysteine peptide, (Ac-RFAACAA-COOH)

lysine peptide (Ac-RFAAKAACOOH)

Details on the study design:

The test item was incubated for 22 h at 25 °C together with Cys- and Lys-peptides, respectively. The peptide concentration after the incubation period was measured using HPLC-UV.
Three replicates were prepared using the test item solution with the Cys- and Lys-peptides,
respectively. On demand of the sponsor and due to solubility of the test item, the tested
concentration was 0.44 mM and therefore lower than the 100 mM, required in the OECD
442C and no 1:10 or 1:50 molar ratio with the respective peptides was tested.
Triplicate samples of the solvent without test item were incubated and measured simultane-
ously.
Three experiments were performed.

Due to solubility of the test item, the tested concentration was lower than the 100 mM, required in the OECD 442C and no 1:10 or 1:50 molar ratio with the respective peptides was tested.

Vehicle / solvent:

acetonitrile

Group:

test chemical

Run / experiment:

run/experiment 3

Parameter:

mean cystein depletion

Value:

12.7 %

Group:

test chemical

Run / experiment:

mean

Parameter:

mean cystein depletion

Remarks:

the results of the Lys-peptide assay of exp. 1 and of the Cys-peptide assay of exp. 2 were used to calculate the mean peptide depletion.

Value:

4.14 %

Group:

test chemical

Run / experiment:

run/experiment 1

Remarks on result:

other: not valid

Interpretation of results:

GHS criteria not met

Conclusions:

The DPRA prediction is “negative” according to the Cysteine 1:10/Lysine 1:50 pre-
diction model. Thus, under the experimental conditions reported and in the tested
concentration 0.44 mM, the test item HEXANITROSTILBENE shows no or minimal
reactivity towards the two model synthetic peptides.

Endpoint conclusion

Endpoint conclusion:

no adverse effect observed (not sensitising)

Respiratory sensitisation

Endpoint conclusion

Endpoint conclusion:

no study available

Justification for classification or non-classification

The first two assays (KeratinoSens™ assay, OECD TG 442D and Human cell-line activation test-h-CLAT, OECD TG 442E) provide discordant results.

The assay for the remaining KE is run (DPRA; OECD TG 442C) confirms the negative result.