Metabolism of Other Tritiated Species

BIOLOGICAL PROPERTIES

DOE-HDBK-1079-94

Tritium Primer

almost completely absorbed by the gastrointestinal tract and quickly appears in the blood stream.

Within minutes, it can be found in varying concentrations in the organs, fluids, and tissues of

the body. Skin absorption of airborne HTO is also important, especially during hot weather,

because of the normal movement of water through the skin. For skin temperatures between 30

and 40 C, the absorption of HTO is about 50% of that for HTO by inhalation (assuming an

average breathing rate associated with light work, 20 L/min). No matter how it is absorbed,

the HTO will be uniformly distributed in all biological fluids within one to two hours. This

tritium has a retention that is characteristic of water. In addition, a small fraction of the tritium

is incorporated into easily exchanged hydrogen sites in organic molecules. Hence, retention of

tritiated water can be described as the sum of several terms: one characteristic of body water,

and one or more longer-term components that represent tritium incorporated into organic

Metabolism of Other Tritiated Species

Most tritium handled in laboratories is in the form of tritiated gas or tritium oxide. However,

tritium handling operations may form other compounds, such as tritiated hydrocarbons and metal

tritides. Tritium may also contaminate surfaces and liquids such as pump oil. These materials

may present special safe handling problems.

Metallic Getters

Although many metals are commonly used for gettering (chemically combining with) tritium,

little information on their metabolic properties is available. Some of these compounds (such as

uranium tritide and lithium tritide) are unstable in air. For these, exposure to air produces

different results. Uranium tritide, being pyrophoric, releases large quantities of tritiated water;

lithium tritide, a hydroxyl scavenger, releases mostly tritium gas.

Tritides of metals (such as titanium, niobium, and zirconium) are stable in air. For particles of

these tritides, the primary organ of concern is the lungs. Some of the tritium may leach out in

the lung fluids and then be incorporated into the body water. These particles may also produce

organically bound tritium from contact with lung tissue, which would further complicate the

metabolic process. However, in laboratories where such tritiated metals are handled, the

possibility for exposure to airborne particulates of these metals is extremely remote except in

accident situations.

Tritiated Liquids

Next to HTO, the most common tritiated liquid is tritiated vacuum pump oil. Experience at

DOE facilities has shown that the specific activities of pump oils can easily range from a few

mCi/L to a few tens of Ci/L. The wide range in specific activities may result from variations in

the tritium concentration and total throughput of tritium. Depending on the history of these

pumps, the tritium may be found as HT, HTO, or tritiated hydrocarbons.

Tritium

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