Kava (Piper methysticum) has long been used in Polynesia as a relaxing beverage, made from the fresh roots in communal settings with the intention of promoting conviviality, community, and peace. While there are some anectdotal reports on long-term abuse leading to "kava skin" (patchy, scaly eruptions that disappear after kava is withdrawn), this plant was always considered safe until 2002, when Germany and other European countries banned its use after liver failure in a patient who had a history of liver disease grossly abused a strong Kava extract and died from liver failure (maybe we should ban whiskey too).
Anyway, in a study that just came out in Phytomedicine, we see interesting new information that, in animal models, doses of kava given daily don't seem to have any toxicity at all, even when administered for long periods of time. This seems to corroborate traditional info. Hopefully it will have an impact in Europe where the use of kava, a potent anxiolytic and relaxant, is still shunned after the 2002 decision.