Estragole or its metabolites administered to mice produce malignant liver tumors.

Estragole is a chemical compound with a molecular formula C10H12O which belongs to alkenylbenzenes. It is also known as 1-allyl-4-methoxybenzene, 3-(p-methoxyphenyl)propane, 4-allyl-1- methoxybenzene, 4-allylanisole, 4-allylmethoxybenzene, 4-methoxyallylbenzene, p-allyl anisole, 1-methoxy-4-(2-propenyl)benzene, chavicol methyl ether, chavicyl methyl ether, esdragol, esdragole, esdragon, estragol, isoanethole, methyl chavicol, o-methyl chavicol, NCI-C60946, p-allylanisole, p-methoxyallylbenzene, and tarragon.

Estragole is metabolized by the liver to 1'-hydroxyestragole and several epoxide compounds. 1'-Hydroxyestragole is further conjugated with sulfate to form a sulfuric acid ester compound that readily binds to DNA and is responsible to most, if not all, of estragole's hepatocellular carcinogenicity in mice. Metabolism of estragole through this pathway appears to be quantitatively consistent among humans and rodents.

Widespread human exposure to estragole occurs through the consumption of basil, bay, marjoram, anise, and fennel herbs. Estragole is a constituent of terpentine oil. Indoor air exposure may result from the use of terpentine oil in furniture and other wood treatments.