Investigators at the U.S. National Fish and Wildlife Forensics Laboratory report that they have found potentially toxic levels of arsenic and mercury in Chinese herbal balls.

Herbal balls are a mixture of medicinal herbs and honey and are dissolved in warm wine or water and then drunk as a tea. The investigators analyzed the balls as part of their effort to prevent the importation of products from endangered species.

They found that the mercury content in the 32 balls tested varied between 7.8 and 621.3 mg per ball while the arsenic content varied between 0.1 and 36.6 mg. The most contaminated preparation was An Gong Niu Huang Wan from the Tung Jen Tang Pharamaceutical Factory in Nanjing. These balls contained between 3.21 and 36.6 mg of arsenic and between 80.7 and 621.3 mg of mercury, most likely in the form of sulfides. The investigators warn that chronic poisoning has been reported in people ingesting as little as 10 mg per day of arsenic sulfide and among people ingesting approximately 260 mg per day of mercury sulfide.

Espinoza, Edgard O., et al. Arsenic and mercury in traditional Chinese herbal balls. The New England Journal of Medicine, Vol. 333, No. 12, September 21, 1995, pp. 803-04