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Description of key information

information requests for skin sensitisation are met by two in vitro studies according both to OECD Guidelines.

Results of both studies are negative and therefore no third study is needed.

Key value for chemical safety assessment

Skin sensitisation

Link to relevant study records
Reference
Endpoint:
skin sensitisation: in chemico
Type of information:
experimental study
Adequacy of study:
key study
Study period:
September 2017 - December 2018
Reliability:
1 (reliable without restriction)
Rationale for reliability incl. deficiencies:
guideline study
Qualifier:
according to
Guideline:
OECD Guideline 442C (In Chemico Skin Sensitisation: Direct Peptide Reactivity Assay (DPRA))
GLP compliance:
yes (incl. certificate)
Type of study:
direct peptide binding assay
Details on study design:
according to Guideline
Positive control results:
The mean peptide depletion and standard deviation of the three replicates of the positive control cinnamaldehyde were in the acceptable range of 60.8 – 100.0 % and ≤ 14.9 %, respectively, for the Cys-peptide.
The mean peptide depletion and standard deviation of the three replicates of the positive control 2,3-Butanedione were in the acceptable range of 10.0 – 45.0 % and ≤ 11.6 %, respectively, for the Lys-peptide.
Key result
Parameter:
other: Depletion of Lys-Peptide
Run / experiment:
mean
Value:
0
Vehicle controls validity:
valid
Negative controls validity:
valid
Positive controls validity:
valid
Key result
Parameter:
other: Depletion of Cys-Peptide
Run / experiment:
mean
Value:
0
Vehicle controls validity:
valid
Negative controls validity:
valid
Positive controls validity:
valid
Other effects / acceptance of results:
The maximum standard deviation for the test item replicates was < 14.9 % for the percent cysteine depletion for the test item.
The maximum standard deviation for the test item replicates was < 11.6 % for the percent lysine depletion for the test item.
Interpretation of results:
study cannot be used for classification
Conclusions:
The DPRA prediction is “negative” with minimal reactivity according to the Cysteine 1:10/Lysine 1:50 prediction model.
Executive summary:

The study was performed in order to evaluate the reactivity of the test item 1,1'-Azobis(cyclohexane-1-carbonitrile) towards cysteine (Cys-) and lysine (Lys-) containing peptides. A test item solution in acetonitrile was incubated 24 ± 2 h at 25 °C together with cysteine and lysine peptides, respectively, and the peptide concentration after the incuba-tion was measured using HPLC-UV.

Three replicates were prepared using 1:10 and 1:50 molar ratio of the test item with the Cys- and Lys-peptide, respectively. Triplicate samples of the solvent without test item were incubated and measured in parallel.

The peptide depletion values after incubation are shown in Table:

 

 Cys-peptide depletion [%]

Lys-Peptide depletion [%]

 

Mean peptide depletion [%]

Experiment  

 0

 0

The DPRA prediction is “negative” with minimal reactivity according to the Cysteine 1:10/Lysine 1:50 prediction model.

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 available information on skin sensitisation is conclusive but not sufficient for classification.