Safrole

Safrole, also known as shikimol, is a phenylpropene. It is a colorless or slightly yellow oily liquid. It is typically extracted from the root-bark or the fruit of sassafras plants in the form of sassafras oil (although commercially available sassafras oil is usually devoid of safrole via a rule passed by the FDA in 1960, see here), or synthesized from other related methylenedioxy compounds. It is the principal component of brown camphor oil, and is found in small amounts in a wide variety of plants, where it functions as a natural pesticide. Ocotea cymbarum oil made from Ocotea pretiosa, a plant growing in Brazil, and sassafras oil made from Sassafras albidum, a tree growing in eastern North America, are the main natural sources for safrole. It has a characteristic "sweet-shop" aroma.

It is a precursor in the synthesis of the insecticide synergist piperonyl butoxide and the entheogenic drug MDMA ("Ecstasy.")

Carcinogenicity
Safrole is regarded by the U.S. government to be a weak carcinogen in rats, and considered by the European Commission on Health and consumer protection to be genotoxic and carcinogenic. It naturally occurs in a variety of spices such as cinnamon, nutmeg, black pepper and herbs such as basil. In that role safrole is believed, although not proven, to make a small but measurable contribution to the overall incidence of human cancer, equal to the hazards presented by orange juice (due to limonene) and tomatoes (caffeic acid). In the United States, it was once widely used as a food additive in root beer, sassafras tea, and other common goods, but was banned by the Food and Drug Administration (FDA) after its carcinogenicity in rats was discovered. Today, safrole is also banned for use in soap and perfumes by the International Fragrance Association.

According to a 1977 study of the metabolites of safrole in both rats and humans, two carcinogenic metabolites of safrole found in the urine of rats, 1'-hydroxysafrole and 3'-hydroxyisosafrole, were not found in human urine.

Use in MDMA manufacture
Due to its role in the manufacture of MDMA, safrole and isosafrole as well as piperonal are Category I precursors under regulation No 273/2004 of the European Community. In the US, safrole is currently a List I chemical. The root bark of American sassafras contains a few percent of steam volatile oil which is typically 75% safrole. Attempts to access safrole from this source are generally not successful because the yield is low and the effort required to get useful amounts of material is great. Safrole is listed as a Table I precursor under the United Nations Convention Against Illicit Traffic in Narcotic Drugs and Psychotropic Substances.