Registration Dossier
Registration Dossier
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EC number: 200-157-7 | CAS number: 52-89-1
Endpoint summary
Administrative data
Description of key information
L-Cysteine hydrochloride monohydrate at concentrations of 10%, 25% or 50% (w/w) in ethanol : water (3+7,v/v) did not reveal sensitising properties in the local lymph node assay with mice.
Key value for chemical safety assessment
Skin sensitisation
Endpoint conclusion
- Endpoint conclusion:
- no adverse effect observed (not sensitising)
- Additional information:
L-Cysteine hydrochloride monohydrate was suspended in a mixture of ethanol : water (3+7,v/v). The test item suspension was administered to the dorsum of the animal's ears. Each test group of 4 female mice was treated by (epidermal) topical open application to the dorsal surface of each ear with test item concentrations of 0, 10, 25 and 50 % (w/w) for three consecutive days. The test was performed according to the guideline: Injection of 3H-methyl thymidine in phosphate-buffered saline, followed by sacrifice, excising the draining auricular lymph nodes, preparation of cell suspensions of lymph node cells and determining the proliferative capacity of poolde lymph node cells by incorporation of 3H-methylthymidine measured in a beta-scintillation counter.
The clinical signs were recorded at least once daily, especially the treatment sites were observed carefully. Weight recorded and ear thickness was measured on certain days.
Results: No deaths occurred during the study period. No symptoms of local skin irritation at the ears of the animals and no signs of systemic toxicity were observed during the study period. The body weight of the animals was within the range commonly recorded for animals of this strain and age.
Stimulation Indices of 2.0, 2.3 and 2.3 were determined with test item concentrations of 10, 25 and 50 %. As the threshold value for a sensitizer of 3 is not reached, l-cysteine hydrochloride monohydrate is classified as not sensitizing.
Respiratory sensitisation
Endpoint conclusion
- Endpoint conclusion:
- no study available
Justification for classification or non-classification
L-Cysteine hydrochloride monohydrate at concentrations of 10%, 25% or 50% (w/w) in ethanol : water (3+7,v/v) did not reveal sensitising properties in the local lymph node assay.
According to Regulation (EC) No.: 1272/2008 and subsequent regulations, the L-Cysteine hydrochloride monohydrate and its anhydrous form are not classified as skin sensitiser.
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