Body & Beauty / Compounds / Safrole

Safrole on your skin: a safety profile

Moderate risk

(People-specific data is limited; this page draws from human adult context.) Safrole is a naturally occurring phenylpropanoid found in the essential oils of sassafras (Sassafras albidum), black pepper (Piper nigrum), star anise, cinnamon, nutmeg, mace, and various other spices and herbs. It was widely used as the principal flavoring agent in root beer in the United States until 1960, when the FDA banned its use as a food additive based on animal carcinogenicity data showing hepatocellular carcinomas in rodents. IARC 2B (Vol 1, 1972) reflects one of the earliest IARC evaluations of a naturally occurring food substance. The mechanism of safrole carcinogenicity involves hepatic oxidation by CYP2C9/CYP3A4 to 1'-hydroxysafrole, followed by sulfotransferase-mediated activation to a reactive sulfate ester that forms N2-guanine DNA adducts characteristic of safrole-induced hepatocarcinogenesis. Despite the FDA ban on intentional addition, safrole remains a natural constituent of several spices used in food at low concentrations — black pepper (approximately 0.01–0.1% safrole in essential oil), star anise, nutmeg, and cinnamon contribute low-level dietary safrole from typical culinary use. Sassafras tea (made from sassafras root bark) contains high concentrations of safrole and was historically used as a folk remedy; it continues to be brewed in some communities despite the ban. Additionally, safrole has become relevant to illicit drug enforcement as a key precursor for MDMA/ecstasy synthesis — trafficking of safrole-containing essential oils (particularly sassafras oil from Cambodia and Southeast Asia) is monitored by law enforcement. The EU restricts safrole as a flavoring substance; maximum limits apply in certain food categories.

What is safrole?

The IUPAC name is 5-prop-2-enyl-1,3-benzodioxole.

Also known as: 5-prop-2-enyl-1,3-benzodioxole, Safrol, Shikimole, Shikomol.

IUPAC name: 5-prop-2-enyl-1,3-benzodioxole
CAS number: 94-59-7
Molecular formula: C10H10O2
Molecular weight: 162.18 g/mol
SMILES: C=CCC1=CC2=C(C=C1)OCO2
PubChem CID: 5144

Risk for people

Moderate risk

Safrole is a naturally occurring phenylpropanoid found in the essential oils of sassafras (Sassafras albidum), black pepper (Piper nigrum), star anise, cinnamon, nutmeg, mace, and various other spices and herbs. It was widely used as the principal flavoring agent in root beer in the United States until 1960, when the FDA banned its use as a food additive based on animal carcinogenicity data showing hepatocellular carcinomas in rodents. IARC 2B (Vol 1, 1972) reflects one of the earliest IARC evaluations of a naturally occurring food substance. The mechanism of safrole carcinogenicity involves hepatic oxidation by CYP2C9/CYP3A4 to 1'-hydroxysafrole, followed by sulfotransferase-mediated activation to a reactive sulfate ester that forms N2-guanine DNA adducts characteristic of safrole-induced hepatocarcinogenesis. Despite the FDA ban on intentional addition, safrole remains a natural constituent of several spices used in food at low concentrations — black pepper (approximately 0.01–0.1% safrole in essential oil), star anise, nutmeg, and cinnamon contribute low-level dietary safrole from typical culinary use. Sassafras tea (made from sassafras root bark) contains high concentrations of safrole and was historically used as a folk remedy; it continues to be brewed in some communities despite the ban. Additionally, safrole has become relevant to illicit drug enforcement as a key precursor for MDMA/ecstasy synthesis — trafficking of safrole-containing essential oils (particularly sassafras oil from Cambodia and Southeast Asia) is monitored by law enforcement. The EU restricts safrole as a flavoring substance; maximum limits apply in certain food categories.

Regulatory consensus

7 regulatory and scientific bodies have classified Safrole. The classifications differ — that's the data.

Agency	Year	Classification
IARC	1972	Group 2B
US EPA	1986	Group B2 – probable human carcinogen
EPA CTX / NTP RoC	—	Reasonably Anticipated to be a Human Carcinogen
EPA CTX / IARC	—	Group 2B - Possibly carcinogenic to humans
EPA CTX / CalEPA	—	Known human carcinogen
EPA CTX / Genetox	—	Genotoxicity: positive (Ames: positive, 8 positive / 4 negative reports)
EPA CTX / Genetox	—	Genotoxicity: positive (Ames: positive, 8 positive / 4 negative reports)

Regulators apply different standards of evidence — animal-data weighting, exposure-pattern assumptions, epidemiological power thresholds — which is why two scientific bodies can review the same data and reach different conclusions. The disagreement is the data.

Where you encounter safrole

Industrial Facilities — Manufacturing plants, Chemical storage areas, Waste treatment sites
Occupational Environments — Factories, Warehouses, Transportation vehicles
Fragrance — perfume, cologne, scented personal care products, household fragrance products, candles
Identified in Fragrance Ingredient Safety Priority Research database (2,325 ingredients)

Safer alternatives

Lower-risk approaches that achieve a similar outcome to Safrole:

Fragrance-free formulations
Trade-offs: Consumer preference for scented products

Relative cost: Lower (ingredient elimination)
Essential oil-based fragrances (with disclosure)
Trade-offs: Natural does not mean safe — many essential oils are skin sensitizers

Relative cost: 2-5× conventional

Frequently asked questions

What products contain safrole?

Safrole appears in: Manufacturing plants (Industrial facilities); Chemical storage areas (Industrial facilities); Factories (Occupational environments); Warehouses (Occupational environments); perfume (Fragrance).

Why do regulators disagree about safrole?

Safrole has been classified by 7 agencies including IARC, US EPA, EPA CTX / NTP RoC, EPA CTX / IARC, EPA CTX / CalEPA, with differing conclusions. Regulators apply different standards of evidence (animal data weighting, exposure-pattern assumptions, epidemiological power thresholds), which is why two scientific bodies can review the same data and reach different conclusions. See the regulatory consensus table on this page for the full picture.

See Safrole in the body app

Look up products containing safrole, compare to alternatives, and explore the full data record.

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Sources (2)

IARC Monographs Volume 1: Some Inorganic Substances, Chlorinated Hydrocarbons, Aromatic Amines, N-Nitroso Compounds and Natural Products — Safrole Group 2B; Sassafras Oil; FDA Root Beer Flavoring Ban 1960; Hepatocellular Carcinoma in Rodents; 1'-Hydroxysafrole Mechanism (1972) — iarc_monograph
US EPA: Safrole — Group B2 Probable Human Carcinogen; Hepatocarcinogenesis; DNA Adducts at Guanine; Black Pepper and Star Anise Dietary Occurrence; MDMA Precursor DEA Scheduling; EU Flavoring Restrictions (1986) — regulatory

Reference data, not professional advice. Aggregates publicly available regulatory and scientific data; not a substitute for veterinary, medical, legal, or regulatory advice. Why we built ALETHEIA →