AN UNEASY conscience is not the only reason why devotees of Chinese medicine might want to avoid preparations that claim to contain rhino horn, tiger bone or other parts of endangered animals. According to forensic experts in the US, these medicines often contain potentially dangerous amounts of arsenic and mercury.
The toxic metals turned up in shipments of eight different types of medicinal herbal balls made in factories in China. The balls were seized at US ports by inspectors from the Fish and Wildlife Service because they listed products from endangered species among their ingredients.
Analysts at the National Fish and Wildlife Forensics Laboratory in Ashland, Oregon, ran samples through their usual screening tests, which include an elemental analysis using X-ray fluorescence and atomic absorption spectroscopy, to look for the large amounts of sulphur, phosphorus and calcium that would suggest the presence of horn and bone.
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None of the eight medicines contained any tiger or rhino parts, despite the claims made on their labels, says Ed Espinoza, the chief of forensic sciences at Ashland. However, at least some balls of every type contained inorganic salts of mercury or arsenic, Espinoza and his colleagues report in last week鈥檚 New England Journal of Medicine. Most contained both metals, in amounts up to 36 milligrams of arsenic and 621 milligrams of mercury per ball. 鈥淚t shocked us,鈥� says Espinoza. 鈥淚t certainly wasn鈥檛 what we expected to find.鈥�
People take Chinese 鈥渢ea balls鈥� for a wide range of ailments, to reduce fever, ease rheumatism and to treat apoplexy and cataracts. The recommended method is usually to dissolve the balls in warm wine or water and drink the resulting 鈥渢ea鈥�.
No ready reference lists toxic thresholds for inorganic mercury or arsenic compounds, says Espinoza. However, other studies have reported poisoning in people taking similar or smaller doses over a prolonged period, which suggests that the herbal balls could be dangerous.
That comes as no surprise to herbalists. 鈥淚t鈥檚 not that we don鈥檛 know they are toxic, but for some particular problems some people believe they are more effective than less toxic substances,鈥� says Dan Bensky, of the Seattle Institute of Oriental Medicine.
Even so, the herbal balls may draw fire from the US Food and Drug Administration, which monitors the safety of drugs and dietary supplements. If the FDA confirms that dangerous levels of the metals are present, it would turn back future shipments of the products, says Brad Stone, spokesman for the agency.