Selenium is a possible cancer preventive agent. A study is in progress to provide information on the pharmacokinetics of selenium in its prototype forms: sodium selenite and selenomethionine. This information is necessary for the determination of time and manner of administration. Integrated kinetic models are being used to interpret the study data. Various body pools have been hypothesized and rates of exchange between them estimated, as well as residence times. The models indicate important kinetic differences between selenite and selenomethionine. Alternative models were used to investigate one of the most important differences, the recirculation of the organic, but not the inorganic. The models have been modified and combined into a single model to better simulate dietary intake of selenium. A workshop, organized jointly with the Chemoprevention Investigational Drug Unit, was held to review the current state of knowledge on the efficacy and toxicity of selenium compounds in preventing cancer in animals and humans. Leading selenium researchers gave presentations providing an overview of the current state of selenium research. Se was regarded in general as a safe substance. Toxicities seen at very high levels of intake were reversible with the discontinuance of the high dose. Animal data were regarded as of relatively minor interest as good human data are available.
