Determination of biokinetic parameters for ingestion of radionuclides of zirconium in animals using stable tracers

Exposure to the radioactive isotope Zr-95, as in nuclear accidents, and to stable zirconium, due to its use in industry, has increased the interest in the biokinetics of this element. Information has been derived mainly from tests performed on animals by means of radioactive tracers. Due to the fact that extrapolation from animals to humans is always open to question, ther e is an increasing need of a methodology which allows data to be obtained d irectly from humans. The use of stable tracers, being ethically justifiable , is a powerful tool for providing this information. As two tracers of the same element must be utilized in order to evaluate gut absorption, an analy tical technique which is capable of distinguishing and measuring simultaneo usly different isotopes of zirconium in biological samples is required. Pre liminary tests on laboratory animals were performed in order to assess the feasibility of the double tracer technique combined with proton activation analysis.