National Toxicology Program

Medicinal herbs are among our oldest medicines and their increasing use is evidence of public interest in alternatives to conventional medicine. Herbal medicines are a multi-billion dollar industry in the United States with more than 1500 botanicals sold as dietary supplements or ethnic traditional medicines. Herbal dietary supplements are not subject to Food and Drug Administration (FDA) pre-market approval to assure their safety or efficacy.

The National Toxicology Program (NTP), held a workshop on herbal medicines in 1998 in response to public concerns regarding the use and efficacy of medicinal herbs and to recent nominations of these products for study. Recommendations from the workshop included a call for (1) more research on herbals, (2) the identification and standardization of product ingredients by industry, and (3) increased consumer education through package inserts.

Staffs at both the NIEHS and NCTR are actively working with the National Institutes of Health (NIH) Office of Dietary Supplements, the Center for Food Safety and Nutrition of the FDA, the academic community, and others to conduct research that will address deficiencies in our knowledge about dietary supplements and herbal medicines and their potential toxicities.

Dietary supplements, containing biologically active constituents found in some herbs and herbal extracts, continue to be nominated and selected for study by the NTP, including some of the most common dietary supplements used by consumers in the United States.

Studies have been designed for many dietary supplements and herbal products that focus on the characterization of potential adverse health effects, including general toxicity associated with short-term high-dose exposure and/or long-term exposure to lower doses, as well as system specific toxicities including reproductive toxicity, neurotoxicity, cardiovascular toxicity and immunotoxicity.

NTP evaluations of these dietary supplements include extensive physico-chemical characterizations of the materials and their constituents, in vivo Good Laboratory Practices toxicological studies, mechanism-based investigative studies, evaluation of pharmacokinetics, and use of in vitro models for evaluation of biological interactions and mechanisms of action.

For contact information visit the Toxicology Branch.