In August 2002, CDC nominated tungsten for study with high priority to the National Toxicology Program (NTP) [external link]. NTP, an interagency program of the U.S. Department of Health and Human Services, is headquartered at the National Institute of Environmental Health Sciences, one of the National Institutes of Health.
NTP routinely conducts short and long-term toxicology studies to assess the potential of an administered chemical agent to cause cancer, developmental, reproductive, immunotoxic, or neurotoxic effects in laboratory rodents (see Objectives & Procedures of NTP Studies [external link]). A formal multi-step process [external link] for evaluating each study nomination provides NTP with federal agency and public input on toxicology research needs and study priorities.
Based on its review of the tungsten nomination to date, NTP is currently planning a program of study to address toxicology research needs for tungsten. There will be additional opportunity for interested parties to comment on research needed to facilitate further assessment of potential adverse health effects of community exposure to tungsten. Though NTP's study programs are long-term in nature, lasting several years, the research will proceed in phases so that results can be made available to interested parties periodically.
- Summary of the Nomination of Tungsten to NTP (Tungsten is the last substance in the chart) [external link]
- Tungsten and Selected Tungsten Compounds: Review of Toxicological Literature [external link] [PDF, 490 Kb]
- NTP Activity: Tungsten Toxicology Study Update (February 2004)
- Following its formal review of the tungsten nomination, NTP selected tungsten for study and is currently planning a program of study to address toxicology research needs. Sodium tungstate dihydrate was selected as the tungsten compound for these studies because of its water solubility and enhanced potential for gastrointestinal absorption. This form of tungsten is expected to closely mimic the human exposure scenario where people are exposed orally to tungsten through their drinking water or food. The NTP's planned studies include short-, intermediate-, and long-term exposure studies designed to assess a variety of toxicological endpoints including carcinogenicity. Rats and mice of both sexes will be exposed to sodium tungstate dihydrate in their drinking water for periods ranging from two weeks to two years. Additional studies in rats and mice will evaluate the distribution and fate of sodium tungstate dihydrate within the body. Though NTP's study programs are long-term in nature, lasting several years, the research will proceed in phases so that results can periodically be made available to interested parties.
The status of the NTP toxicology study can be tracked by
- searching the NTP Web site [external link]
- contacting the NTP Liaison and Scientific Review Office at
visit the Web site
[external link] for more contacts.