Is Cystine safe in cosmetics?
Cystine has a safety rating of "GOOD" in our database. EU status: permitted. US status: permitted. 10 toxicological study endpoint(s) are available in our database.
Cystine
Also known as: 4-04-00-03155, Alanine, 3,3'-dithiodi-, Bis(beta-amino-beta-carboxyethyl)disulfide, BRN 1728094, Cystine (L)- (+14 more)
INCI: CYSTINE
Cystine (CAS 56-89-3) is a cosmetic cosmetic ingredient functioning as Antistatic, Fragrance, Hair Conditioning, Skin Conditioning. NOAEL 600 mg/kg bw/day (cross-referenced against ToxValDB ECHA IUCLID); EU Regulation 1223/2009 status: permitted. Industrial safety data is also available in the chemical safety database. Same-CAS public records also appear in industrial chemical safety, pharmaceutical, and food safety data.
View industrial chemical safety profile for CAS 56-89-3 →
Auto-generated CPSR Part A draft with source citations
Function
Antistatic, Fragrance, Hair Conditioning, Skin Conditioning
Safety Rating
GOOD
Chemistry & Identifiers
IUPAC Name
(2R)-2-amino-3-[[(2R)-2-amino-2-carboxyethyl]disulfanyl]propanoic acid
InChIKey
LEVWYRKDKASIDU-IMJSIDKUSA-N
Regulatory Status
EU EU Status
permitted
US US Status
permitted
US Notes
CIR affirmed safe as used (2013). L-Cystine is GRAS for food use.
For full compliance data across multiple jurisdictions, use the Substance Compliance tool.
Safety Data
Margin of Safety, dermal absorption, and sensitization profile summaries for Cystine.
Calculate MoS for your specific formulation with the MoS Calculator.
Toxicological Studies
10 study endpoints found for Cystine. NOAEL (No Observed Adverse Effect Level) values are used to calculate the Margin of Safety per SCCS methodology.
| Endpoint | Value | Route | Species | Study Type | Source |
|---|---|---|---|---|---|
| NOAEL | 500 mg/kg bw/day | oral | rabbit | Short Term Toxicity | COSMOS_DB |
| NOAEL | 1500 mg/kg bw/day | oral | rat | Short Term Toxicity | COSMOS_DB |
| NOAEL | 1792 mg/kg bw/day | oral | rat | Short Term Toxicity | COSMOS_DB |
| NOAEL | 1875 mg/kg bw/day | oral | rat | Short Term Toxicity | COSMOS_DB |
| NOAEL | 1958 mg/kg bw/day | oral | rat | Short Term Toxicity | COSMOS_DB |
| NOAEL | 2000 mg/kg bw/day | oral | rat | Short Term Toxicity | COSMOS_DB |
| NOAEL | 2083 mg/kg bw/day | oral | rat | Short Term Toxicity | COSMOS_DB |
| NOAEL | 2500 mg/kg bw/day | oral | cat | Chronic | COSMOS_DB |
| NOAEL | 3500 mg/kg bw/day | oral | rat | Short Term Toxicity | COSMOS_DB |
| NOAEL | 5000 mg/kg bw/day | oral | rat | Short Term Toxicity | COSMOS_DB |
Pre-Calculated Safety Assessment
Pre-calculated NOAEL → SED → MoS audit trail for Cystine across SCCS product categories, with measured dermal absorption where available.
ECHA REACH Registration
European Chemicals Agency REACH dossier and Substances of Very High Concern listing.
Registration Type
Full
Tonnage Band
100 - 1,000 tonnes
Substance Type
SUBSTANCE
SVHC Candidate
No
Function Categories & List Membership
Cosmetic/Chemical Function Categories
Anti-static agent
Deodorizer
Filler
Flavouring and nutrient
Softener and conditioner
Regulatory List Membership (1)
FDA Substances Added to Food (EAFUS)
Expert Verdict
Expert safety assessment and concern-level summary for Cystine.
Regulatory Flags
fda_food_additive
NOAEL Studies Summary
View details ->Public NOAEL study rows linked to Cystine by CAS number or substance name.
Studies
11
Lowest NOAEL
500 mg/kg bw/day
Highest NOAEL
5230 mg/kg bw/day
COSMOS_DB
Known Synonyms
4-04-00-03155
Alanine, 3,3'-dithiodi-
Bis(beta-amino-beta-carboxyethyl)disulfide
BRN 1728094
Cystine (L)-
beta,beta'-Diamino-beta,beta'-dicarboxydiethyldisulfide
beta,beta'-Dithioalanine, L-
(R-(R*,R*))-3,3'-Dithiobis(2-aminopropanoic acid)
3,3'-Dithiobis(2-aminopropanoic acid), (R-(R*,R*))-
EINECS 200-296-3
Propanoic acid, 3,3'-dithiobis(2-amino-, (R-(R*,R*))-
UNII-48TCX9A1VT
(2R)-2-amino-3-[(2R)-2-amino-2-carboxy-ethyl]disulfanyl-propanoic acid
(2R)-2-amino-3-{[(2R)-2-amino-2-carboxyethyl]disulfanyl}propanoic acid
(R-(R*,R*))-3,3'-Dithiobis
2-Amino-3-(2-amino-2-carboxy-ethyl)disulfanyl-propanoate
2-Amino-3-(2-amino-2-carboxy-ethyl)disulfanyl-propanoic acid
2-Amino-3-[(2-amino-2-carboxyethyl)dithio]propanoate
2-Amino-3-[(2-amino-2-carboxyethyl)dithio]propanoic acid
Chemical Function
Anti-static agent
Deodorizer
Softener and conditioner
Flavouring and nutrient
Filler
Regulatory Lists
Europe
food_additive; Substances Added to Food (formerly EAFUS) (2/2019)
Cross-Vertical Safety Context
Same-CAS public records found in pharmaceutical and food safety data.
SOURCE
ChEMBL / DrugCentral / FAERS
DB_PHARMA CAS match
Pharmaceutical Data
Same-CAS rows from the pharmaceutical spoke database.
Compound
CYSTINE
ChEMBL ID
CHEMBL590540
Max Phase
2
SOURCE
EFSA / FDA GRAS
food_additives
Food Safety Data
Same-CAS food additive or FDA GRAS records from the core public database.
Food Name
L-CYSTINE
Food Category
flavoring
Frequently Asked Questions
Is Cystine allowed in the EU?
Cystine EU regulatory status: permitted. This is based on EU Regulation 1223/2009 and its amendments.
What does Cystine do in cosmetics?
Cystine functions as: Antistatic, Fragrance, Hair Conditioning, Skin Conditioning. It is classified as a cosmetic ingredient in our database. CAS number: 56-89-3.
What is the NOAEL for Cystine?
The NOAEL (No Observed Adverse Effect Level) for Cystine is 500 mg/kg bw/day based on a Short Term Toxicity study via oral route in rabbit. A total of 10 study endpoints are available. Source: COSMOS_DB.
Is Cystine used outside cosmetics?
Cystine also appears in industrial chemical safety, pharmaceutical, and food safety data. The cross-vertical cards on this page render same-CAS public rows from the matched databases.
Compliance Tools
Check Cystine compliance across multiple jurisdictions:
Ingredient Decoder
Paste a full ingredient list for instant analysis
82 Allergen Checker
Check for EU declarable fragrance allergens
Substance Compliance
Check compliance across multiple jurisdictions
MoS Calculator
Calculate Margin of Safety using SCCS methodology
Heavy Metal Limits
Compare limits across jurisdictions
Related Ingredients
L-Isoleucine
Excellent
Same category
Antistatic, Hair Conditioning, Skin C...
L-Alanine
Good
Same category
Skin Conditioning (Humectant), Hair C...
L-Aspartic Acid
Good
Same category
Skin Conditioning (Humectant), Hair C...
L-Methionine
Good
Same category
Antistatic, Hair Conditioning, Skin C...
L-Serine
Good
Same category
Skin Conditioning (Humectant), Hair C...
L-Threonine
Good
Same category
Antistatic, Hair Conditioning, Hair W...
(AGARICUS BLAZEI FERMENT + GANODERMA LUCIDUM FERMENT + GANODERMA MULTIPILEUM FERMENT) EXTRACT
Good
Similar safety
Anti-sebum, Antioxidant, Skin Protecting
(ANGELICA ACUTILOBA/PAEONIA LACTIFLORA/REHMANNIA GLUTINOSA) ROOT/CNIDIUM OFFICINALE RHIZOME EXTRACT
Good
Similar safety
Skin Conditioning, Skin Conditioning ...
(ANGELICA ACUTILOBA/PAEONIA LACTIFLORA/REHMANNIA GLUTINOSA/SCUTELLARIA BAICALENSIS) ROOT/(CNIDIUM OFFICINALE/COPTIS CHINENSIS) RHIZOME/GARDENIA JASMINOIDES FRUIT/PHELLODENDRON CHINENSE BARK EXTRACT
Good
Similar safety
(ANGELICA GIGAS/GLYCYRRHIZA URALENSIS/REHMANNIA GLUTINOSA ROOT)/ANGELICA GIGAS STEM/CARTHAMUS TINCTORIUS FLOWER/(CARTHAMUS TINCTORIUS/PRUNUS PERSICA SEED)PORIA COCOS WATER
Good
Similar safety
Humectant, Skin Conditioning, Skin Pr...
(ANGELICA KEISKEI/CHRYSANTHEMUM ZAWADSKII) LEAF/STEM/CINNAMOMUM CASSIA BARK/TRICHOSANTES KIRILOWII FRUIT/ULMUS DAVIDIANA BARK/ROOT/(PAEONIA JAPONICA/BUPLEURUM FALCATUM/POLYGALA TENUIFOLIA ROOT)/VISCUS ALBUM STEM EXTRACT
Good
Similar safety
Anti-seborrheic, Anti-sebum, Antioxid...
(APPLE/CITRUS JUNOS/LENTIL/PEAR/PUMPKIN/STRAWBERRY/TOMATO FRUIT)/CORN KERNEL/(ARCTIUM LAPPA/BRASSICA OLERACEA ACEPHALA/CABBAGE/CAMELLIA SINENSIS/MORINGA OLEIFERA/RADISH/SPINACH LEAF)/(SORGHUM BICOLOR LEAF/STEM)/OAT MEAL/POTATO PULP/(CARROT/NELUMBO NUCIFERA/RADISH/WILD YAM ROOT)/(AMARANTHUS HYPOCHONDRIACUS/CASHEW/CICER ARIETINUM/COIX LACRYMA-JOBI MA-YUEN /MACADAMIA TERNIFOLIA/PHASEOLUS ANGULARIS/PISTACIA VERA/RHYNCHOSIA NULUBILIS/RICE/SESAME/SETARIA ITALICA/SOYBEAN/SWEET ALMOND/WHEAT SEED)/HORDEUM VULGARE SPROUT/CYPERUS ESCULENTUS TUBER/ARTEMISIA PRINCEPS/BROCCOLI/CHENOPODIUM QUINOA/ENTEROMORPHA COMPRESSA/HORDEUM VULGARE/IPOMOEA BATATAS/LAMINARIA JAPONICA/LENTINUS EDODES/PLEUROTUS OSTREATUS/PORPHYRA TENERA/UNDARIA PINNATIFIDA EXTRACT
Good
Similar safety
Antioxidant
Adenosine Triphosphate
Good
Chemical family
Skin Conditioning Agent – Miscellaneous
Adenosine Triphosphate (ATP)
Good
Chemical family
skin-conditioning agent - miscellaneous
Alanine
Excellent
Chemical family
skin conditioning, hair conditioning,...
Is Cystine in Your Products?
Scan any product label with Piro — our free ingredient scanner. Point your camera at the ingredients list and get instant safety scores for every ingredient.
Try Piro Free →Analyze Your Full Ingredient List
Paste any INCI list into the Decoder for instant safety analysis, or calculate the Margin of Safety for Cystine in your formulation.