A 1985 plutonium puncture wound resulted in the initial deposition of 48 kBq of transuranic alpha activity, primarily 239+240Pu and 241Am, in a worker's right index finger. Surgical excisions in the week following reduced the long-term residual wound activity to 5.4 kBq, and 164 DTPA chelation therapy administrations over 17 mo resulted in urinary excretion of about 7 kBq. The case was published in 1988, but now 24 y of follow-up data are available. Annual bioassays have included in-vivo measurements of 241Am in the wound, skeleton, liver, lung, and axillary lymph nodes, and urinalyses for plutonium and 241Am. These measurements have shown relatively stable levels of 241Am at the wound site, with gradually increasing amounts of 241Am detected in the skeleton. Liver measurements have shown erratic detection of 241Am, and the lung measurements indicate Am but as interference from activity in the axillary lymph nodes and skeleton rather than activity in the lung. Urine excretion of Pu since termination of chelation therapy has typically ranged from 10 to 20 mBq d, with Am excretion about 10% of that for 239+240Pu. Annual routine medical exams have not identified any adverse health effects associated with the intake.

PrefaceThis manual provides the scientific and technical foundations for bioassay program design and interpretation, and for the assessment of occupational intakes and internal doses. The Hanford Internal Dosimetry Project Manual (PNNL-MA-552) (a) applies these foundations to define the recommended worker bioassay monitoring programs and internal dose assessment efforts at the Hanford Site.According to the DOE Internal Dosimetry Program Guide (DOE G 441.1-3, 03-17-99), a technical basis document should record the approach to evaluating internal doses from bioassay data, and where appropriate, from workplace monitoring data. It should also describe the physical and chemical characteristics of radioactive materials encountered in the workplace; methods for calculating internal doses and dose equivalents and the methods for documenting those calculations; dose evaluation quality assurance; recording and reporting practices for internal dosimetry; selection of workers for monitoring; and establishment of the type and frequency of measurements to be used. Furthermore, statistical methods for evaluating bioassay data, identifying bioassay results above environmental background values, using appropriate blanks, and analyzing trends should be described.This manual describes the basic methods and biokinetic models used for bioassay program design, interpretation, and internal dose assessment. These methods and models are combined with good practices and professional judgment to give the operational recommendations for routine and special bioassay monitoring contained in the Hanford Internal Dosimetry Project Manual (PNNL-MA-552). The actual selection of workers for monitoring and the characterization of the physical, chemical, and radiological properties of contaminants in the many Hanford facilities are the domain of the individual Hanford contractors.The recommendations in this manual are provided as guidance, not requirements, to personnel responsible for designing and operating bioassay monitoring programs and evaluating bioassay results. Commitments by contractors to use these recommendations may be found in the contractor radiation protection plans. This manual is on a 3-year revision schedule, however individual sections are revised as necessary, and upon revision, commence their own 3-year revision cycle.

During the decommissioning and maintenance of some of the facilities at the U.S. Department of Energy Hanford Site in Washington State, workers have potential for a Sr intake. However, because of worldwide radioactive fallout, Sr is present in our environment and can be detectable in routine urine bioassay samples. It is important for the Hanford Site bioassay program to discriminate an occupational intake from a non-occupational environmental one. A detailed study of the background Sr in the urine of unexposed Hanford workers was performed. A survey of the Hanford Site bioassay database found 128 Hanford workers who were hired between 1997 and 2002 and who had a very low potential for an occupational exposure prior to the baseline strontium urinalysis. Each urinalysis sample represented excretion during an approximate 24-h period. The arithmetic mean value for the 128 pre-exposure baselines was 3.6 +/- 5.1 mBq d. The 99 percentile result was 17 mBq d, which was interpreted to mean that 1% of Hanford workers not occupationally exposed to strontium might exceed 17 mBq d.

The capabilities of indirect radiobioassay by urine and fecal sample analysis were compared with the direct radiobioassay methods of whole body counting and lung counting for the most common radionuclides and inhalation exposure scenarios encountered by Hanford workers. Radionuclides addressed by in vivo measurement included 137Cs, 60Co, 154Eu, and 241Am as an indicator for plutonium mixtures. The same radionuclides were addressed using gamma energy analysis of urine samples, augmented by radiochemistry and alpha spectrometry methods for plutonium in urine and fecal samples. It was concluded that in vivo whole body counting and lung counting capability should be maintained at the Hanford Site for the foreseeable future, however, urine and fecal sample analysis could provide adequate, though degraded, monitoring capability for workers as a short-term alternative, should in vivo capability be lost due to planned or unplanned circumstances.

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