α-Thujone in food: ingestion safety

What is α-thujone?

The IUPAC name is (1S,4R,5R)-4-methyl-1-propan-2-ylbicyclo[3.1.0]hexan-3-one.

Also known as: (1S,4R,5R)-4-methyl-1-propan-2-ylbicyclo[3.1.0]hexan-3-one, alpha-Thujone, THUJONE, (-)-alpha-thujone.

IUPAC name

(1S,4R,5R)-4-methyl-1-propan-2-ylbicyclo[3.1.0]hexan-3-one

CAS number

546-80-5

Molecular formula

C10H16O

Molecular weight

152.23 g/mol

SMILES

CC1C2CC2(CC1=O)C(C)C

PubChem CID

261491

Regulatory consensus

1 regulatory bodyhas classified α-Thujone.

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 α-thujone

• Food — absinthe, sage, thuja (cedar leaf)
• Personal Care — essential oils containing thujone (sage, wormwood, tansy)
• 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 α-Thujone:

• Avoidance (no chemical substitute)
  Trade-offs: Direct chemical substitution requires verification that the replacement does not introduce new hazards (regrettable substitution). Conduct full hazard assessment of proposed alternative before adoption.
  Relative cost: 1.2-2×

Frequently asked questions