It is a precursor in the synthesis of the insecticide synergist piperonyl butoxide.
Safrole is a weak carcinogen. It naturally occurs in a variety of spices, for example basil, cinnamon, nutmeg, and pepper. In that role safrole is believed to make a small but measurable contribution to the overall incidence of human cancer. In the US, 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 was discovered. Today, safrole is also banned for use in soap and perfumes by IFRA.
It is nearly impossible to obtain large quantities of safrole and/or sassafras oil without arousing the suspicion of law enforcement, as both 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 as 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.