Thorium is a naturally occurring, radioactive substance that exists in combination with other minerals. Small quantities of thorium can be found in all rocks, soil, water, plants, and animals.

Virtually all 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 which continues to break down until a stable product is formed. Radioactive substances, including radium and radon, are continually produced throughout these decay processes and give off alpha, beta, and gamma radiation.

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

How You Are Exposed

Everyone is exposed to small amounts of thorium in air, water, and food. It is possible to be exposed to higher levels of thorium in the air near facilities where uranium, phosphate, or tin ore are processed. If your house is built on soil with high levels of thorium or you live near a radioactive waste disposal site, your chances of being exposed to significant levels of thorium are increased. Higher-than-normal exposure is also likely if you work in the uranium, thorium, tin, and phosphate mining industries or in gas mantle production.

How Can Thorium Affect Your Health?

Research has found that thorium workers who have been exposed to high levels of thorium dust in the air have an increased chance of developing lung disease. Animal research has also found that breathing thorium may cause lung damage. Liver diseases and changes in the blood were seen in individuals that had been given thorotrast, a thorium compound injected into the body as a radiographic contrast medium during the years 1928-1955. Injections of thorium for special x-ray tests have also been linked to an increased incidence of liver tumors, cancers of the blood such as leukemia, and tumors of the bone, kidney, spleen, and pancreas.