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
The oral LD50 of L-Cysteine hydrochloride monohydrate is higher than 2000 mg/kg bw. in the rat.
The dermal LD50 of the test item L-Cysteine hydrochloride monohydrate is higher than 2000 mg/kg bw. by dermal route in the rat.
In accordance with article 2(7)(b) and Annex V 6., REACH the hydrate free form of L-Cysteine hydrochloride is registered. L-Cysteine hydrochloride monohydrate (CAS 7048-04-6, hydrate part of the molecule = 10.25 %) is the manufactured and imported substance and was used for testing.
It is generally accepted that water and especially water of crystallisation has no toxicologically relevant effects. Therefore, the effect levels of L-Cysteine hydrochloride monohydrate can be used to calculate the corresponding dosages of L-Cysteine hydrochloride (anhydrous (free of water of crystallisation)).
Thus, the conclusion on hazard assessment and classification holds true for the anhydrous form as well.
Key value for chemical safety assessment
Acute toxicity: via oral route
Endpoint conclusion
- Endpoint conclusion:
- no adverse effect observed
- Dose descriptor:
- LD50
- Value:
- > 2 000 mg/kg bw
Acute toxicity: via inhalation route
Endpoint conclusion
- Endpoint conclusion:
- no study available
Acute toxicity: via dermal route
Endpoint conclusion
- Endpoint conclusion:
- no adverse effect observed
- Dose descriptor:
- LD50
- Value:
- > 2 000 mg/kg bw
Additional information
L-Cysteine hydrochloride monohydrate was administered to a group of 6 female Sprague-Dawley rats at a single oral dose of 2000 mg/kg bw. in 10 ml/kg bw. distilled water by stomach tube.
No moraltity, no clinical signs and no changed body weight evolution were found during the 14 day observation period. The macroscopic examination of the animals at the end of the study did not reveal treatment related changes.
L-Cysteine hydrochloride monohydrate was applied to the skin of 5 male and 5 female Sprague-Dawley rats at a dose of 2000 mg/kg bw.in 10 ml/kg bw water for 24 hours in an occlusive way. After 24 hours the gauze dressings were removed. The animals were observed for 14 days.
No mortality, no clinical signs, no influence on the body weight evolution and no macroscopic findings at the end of the study were seen.
The LD50 is higher than 2000 mg/kg bw.
Justification for classification or non-classification
In accordance with OECD guideline No. 402 and 423, the oral and the dermal LD50 cut-off may be condsidered to be higher than 5000 mg/kg bw. in the rat.
According to Regulation EC No. 1272/2008 L-Cysteine hydrochloride monohydrate and its anhydrous form does not have to be classified, no signal word or hazard statement is required.
Information on Registered Substances comes from registration dossiers which have been assigned a registration number. The assignment of a registration number does however not guarantee that the information in the dossier is correct or that the dossier is compliant with Regulation (EC) No 1907/2006 (the REACH Regulation). This information has not been reviewed or verified by the Agency or any other authority. The content is subject to change without prior notice.
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