Safrole

• rhymes with arteriole, bronchiole, and vacuole
• also known as shikimol or 5-allylbenzo-1,3-dioxole
• a colourless to slightly yellow (think the colour range of healthy pee) oily liquid at room temperature
• extracted from the root bark of the sassafras tree and also present in low levels in numerous other plants
• has been used as a flavouring agent in root beer (the original flavour), sassafras tea, and other foods
• in 1960, the FDA banned its use in the USA as a food additive after is was found that it causes liver cancer in rats
• no reported cases of liver toxicity or cancer in humans have been attributed to sassafras consumption - it is important to realize that not all substances that are carcinogenic in lab animals cause cancer in humans (i.e. animal models do not always predict the toxic effects of a substance in humans)
• is used in the synthesis of piperonyl butoxide (added to insecticides to increase their potency) and the mood-modifying amphetamines MDMA (Ecstacy) and MDE (Eve)
  

http://en.wikipedia.org/wiki/Safrole