Thorium

What is Thorium?

CAS#: 007440-29-1

Thorium is a naturally occurring, radioactive substance. In the environment, thorium exists in combination with other minerals, such as silica. Small amounts of thorium are present in all rocks, soil, water, plants, and animals. Soil contains an average of about 6 parts of thorium per million parts of soil (6 ppm).

More than 99% of natural thorium exists in the form of thorium-232. It breaks down into two parts-a small part called "alpha" radiation and a large part called the decay product. The decay product is also not stable and continues to break down through a series of decay products until a stable product is formed. During these decay processes, radioactive substances are produced. These include radium and radon. These substances give off radiation, including alpha and beta particles, and gamma radiation.

Some rocks in underground mines contain thorium in a more concentrated form. After these rocks are mined, thorium is usually concentrated and changed into thorium dioxide or other chemical forms. After most of the thorium is removed, the rocks are called "depleted" ore or tailings.

Thorium is used to make ceramics, gas lantern mantles, and metals used in the aerospace industry and in nuclear reactions. Thorium can also be used as a fuel for generating nuclear energy.

Related Resources for Thorium

• CERCLA Priority List of Hazardous Substance
  Prioritization of substances based on a combination of their frequency, toxicity, and potential for human exposure at National Priorities List (NPL) sites.
  
• Public Health Statement
  Summary about a hazardous substance taken from Chapter One of its respective ATSDR Toxicological Profile.
  
• ToxFAQ
  Fact sheet that answers the most frequently asked questions about a contaminant and its health effects.
  
• Toxicological Profile
  Succinctly characterizes the toxicologic and adverse health effects information for a hazardous substance.