Issues

 Issues in bioassay and internal dosimetry identified at the EFCOG workshop, May 1998, include: 

1. Meaning and use of the terms "decision level" and "minimum detectable amount."  Those favoring classical statistics accepted the definitions in ANSI/HPS N13.30-1996.
2. The need for a threshold below which doses are neither calculated nor recorded.  The EFCOG group agreed that "Consideration should be given to establish a limit of 10 mrem CEDE for isolated intakes (not for all intakes, not for chronic intakes) for calculating and recording occupational dose."
3. Which statistical methods should be used, classical or Bayesian?  If Bayesian methods are used, how should the prior be determined?  What considerations go into choosing alpha and beta, the probabilities of false positives and false negatives?  The use of Bayesian methods was covered in some detail at a November, 1997, DOE-sponsored workshop on application of Bayesian statistical methods to bioassay measurements. A summary of the workshop and related links are available at the Bayesian Statistical Methods for Bioassay, Radiochemistry, and Internal Dosimetry web site. 
4. How should suspected intakes be confirmed?
5. What are the advantages and drawbacks of processing radiobioassay samples on site and off site, i.e., in-house or by a radiobioassay service laboratory?
6. What background should be used in decision level calculations, a paired blank, a rolling average, ...?
7. To what extent is long-term medical or dosimetric follow-up of terminated workers warranted?
8. How should workers be identified for bioassay and their particpation ensured?
9. For several radionuclides, it is important to distinguish occupational from non-occupational exposures.  Because uranium is ubiquitous and excretion is measurable in non-occupationally exposed populations, the screening level needs to be set taking into account non-occupational exposures.  What are acceptable methods for dealing with uranium background in urine?  How should elevated levels of Cs-137 be handled?
10. What turnaround times are practical, affordable, and adequate for bioassay sample analysis?
11. How should new ICRP biokinetic models be used, and what will be their impact?
12. What are the best or state-of-the-art methods of doing plutonium bioassay, including TIMS, ICP-MS, fission track, etc.?
13. What constitutes a reasonable effort on the part of a contractor to ensure participation in termination bioassay programs?
14. How can urgent requests for dose estimates best be met when there are only inadequate and preliminary data available that will result in a highly uncertain and possibly seriously erroneous dose estimate?
15. In an era of declining resources, how can bioassay and internal dosimetry programs best support the goals of litigation prevention or litigation evidence?
16. How can balance be achieved between resource expenditures for incidents and accidents and the needs of a routine program?
17. What are the best ways of communicating preliminary dose assessment results to workers?
18. What are the best ways to manage workers who are suspected of having intakes?
19. What are the best features of contracts with radiobioassay service laboratories?
20. What are the issues concerning quality assurance, oversight, and accreditation of radiobioassay service laboratories?
21. How should internal dosimetrists deal with biological variability, especially in fecal data, and deal with normalization and statistical variability?

These and other issues will be addressed by BIDUG.