WASHINGTON — A host of potential toxins, allergens and traces of endangered animals showed up in DNA sequencing tests on 15 Chinese traditional medicines, researchers said on Thursday.
Such therapies have been used in China for more than 3,000 years, but have risen in popularity outside Asia in recent decades and now amount to a global industry worth hundreds of millions of dollars a year, according to the study in PLoS Genetics.
Despite their popularity, little scientific evidence exists to prove the benefits of Chinese traditional medicines (TCMs), and a growing body of research has begun to point to their potential dangers.
The samples analyzed for this study included herbal teas, capsules, powders and flakes that were seized by Australian border officials and were subsequently tested by scientists at Australia's Murdoch University.
Plant agents suspected of causing urinary tract and kidney cancer such as Aristolochic acid, as well as the potentially poisonous herb ephedra were among the dangerous elements found.
"TCMs have a long cultural history, but today consumers need to be aware of the legal and health safety issues before adopting them as a treatment option," said lead researcher Michael Bunce, a Murdoch University Australian Research Council Future Fellow.
Some of the 68 different plant families that were detected in the 15 samples can be toxic if taken in the wrong doses, but the packaging did not list the concentrations of the elements inside, he said.
"We also found traces from trade restricted animals that are classified as vulnerable, endangered, or critically endangered, including the Asiatic black bear and Saiga antelope" he said, adding that some contained ingredients that were not included on the label.
"A product labeled as 100 percent Saiga antelope contained considerable quantities of goat and sheep DNA," he said.
"Another product, Mongnan Tianbao pills, contained deer and cow DNA, the latter of which may violate some religious or cultural strictures."
Performing any in-depth analysis of the biological elements contained in traditional therapies has been difficult in the past because the act of processing ingredients into powders and pills mingled the components too much.
But the approach used by researchers for this study, described as second-generation, high throughput sequencing, was both efficient and cost-effective, said researcher Megan Coghlan.
"The approach has the ability to unravel complex mixtures of plant and animal products," she said.
"We found multiple samples that contained DNA from animals listed as trade-restricted according to the Convention on International Trade in Endangered Species Legislation. Put simply, these TCMs are not legal."
Future tests could help customs officials track the illegal trade of endangered species as well as clamp down on dangerous ingredients, she added.