During a period of time where demand for kava in Europe was incredibly high, distributors were purchasing & using the tudei variety of kava (known to be somewhat toxic) because it was fast-growing. They were also incorporating leaves and stems into the blend of dried kava root.
It has been well known for hundreds of years that parts of the kava plant other than the root can be toxic and should not be consumed. It was assumed that due to these lapses in quality control, around 80 reports of liver failure were linked to kava consumption.
However, upon investigation by the World Health Organization, it was later found that only a few of these cases could truly be associated with kava consumption, and many of them were cases of individuals who were consuming large quantities of alcohol and other narcotic drugs, in addition to kava supplements in pill form.
Later, in 2014, Germany’s Federal Administrative Court ruled that “it was unlikely that kava had caused the deaths, that liver damage from kava was so rare as to be negligible.” The 12-year ban on Kava in Germany was reversed, and said to have been “unlawful and inappropriate”.
More modern research has shown no link between the consumption of noble kava based products and liver issues, even when consumed at many times the recommended pharmacological dose of active constituents.
"The WHO’s second kava risk assessment in 2016 reported: “On balance, the weight of evidence from both a long history of use of kava beverage and from the more recent research findings indicate that it is possible for kava beverage to be consumed with an acceptably low level of health risk.” This level of risk gives kava a vastly higher degree of safety than that given to alcohol and tobacco, or to over-the-counter medications like paracetamol."
Source: “De-mythologizing and re-branding the traditional drink kava” DOI: 10.32907/RO-113-106109
Conclusion: Kava is safe to consume in the traditional method; the dried ground root mixed with water. It is considered to be at a risk-level much lower than alcohol, marijuana, or over-the-counter medications like tylenol.
