Difficulties in in-vitro dose assessment due to chemical limitations

The current regulatory environment and the application of ALARA to radiation protection programs creates an ever increasing pressure to document and evaluate very low-level exposures. This can generally be accomplished either by tighter controls on the process, increased sampling frequency, or decreasing the MDA. In the past, the health physicist's response to these pressures generally has been to require lower and lower MDA's. The introduction of new technology has generally allowed the analytical chemist to accommodate those requests. The purpose of this paper is to point out that one is reaching MDA's that are near ambient levels (or in some cases below) and further decreases may not be feasible without significant price increases. The authors discuss some present difficulties associated with current in-vitro analyses (urine and fecal) in particular for radionuclides of major interest, such as Sr-89 and -90, U and Pu-238,239/240