Nature Scientific Reports published an article "Combined DNA, toxicological and heavy metal analyses provides an auditing toolkit to improve pharmacovigilance of traditional Chinese medicine (TCM)". This research is valuable because it raises the concern over the unregulated TCM market and the safety of TCM medicines. The toxicity due to heavy metals is particularly alarming and warrants systematic investigation, because unlike biological toxicity, chemical toxicity cannot be reduced at an elevated temperature under which TCM medicines are typically prepared.
What is not obvious, however, in reading this article is that this type of research has one common idiosyncrasy: disproportionally picking somewhat poisonous and toxic TCM medicines, and non-plant-based medicines. In actual TCM practice, plant-based medicines (herbs) are used very much more frequently than animal- and mineral-based ones, and a professional TCM doctor is well aware of toxicity of commonly used medicines, such as Asarum, one of those researchers' favorite victims. Naturally, a "surprise" in finding toxicity in these medicines can only come from less-informed lay persons or non-practitioners.
In future studies, the researchers should select medicines based on their usage or prescription frequency. If there's no aggregate or frequency statistics on the prescribed medicine names, one way to create an approximate frequency list is mine, created about ten years ago based on herb name occurrence on the Internet. See http://yong321.freeshell.org/misc/HerbFrequency.html with its result at http://yong321.freeshell.org/misc/HerbFrequencyG.txt.