The researchers randomly chose 230 sites to order the medicines in 2005 and sent their purchases to the New England Regional Environmental Protection Agency for testing. The agency measured metal concentrations using x-ray fluorescence spectroscopy and found that 20.7 percent of the products contained lead, mercury, and/or arsenic.
Of the products manufactured in the United States, 21.7 percent contained metals. Of the Indian-manufactured products, 19.5 percent contained metals. Those identified as containing metal contained enough metal to be considered toxic according to one or more acceptable standards for daily intake.
The highest concentrations of metals were found in a type of Ayurvedic product known as ``rasa shastra,'' in which mercury, lead, zinc and other metals are deliberately combined with herbs to produce a therapeutic effect.
Robert B. Saper of Boston University School of Medicine, the study's lead author, recommended that consumers avoid remedies labeled as rasa shastra products. He also called for tougher regulations for dietary supplements.
The new federal regulations and current Indian policies do not specify any maximum acceptable concentrations or daily dose limits for metals in dietary supplements for domestic use. The study was published in the Journal of the American Medical Association.
Ayurveda is an ancient Indian medical practice. It has become more popular in the U.S. as interest in yoga and alternative medicine has grown.
