Long-term Follow-up Bioassay Programs

DOE-STD-1136-2004

Guide of Good Practices for Occupational Radiological Protection in Uranium Facilities

following intake. This permits a sensitive assessment of potential intake and internal dose. Longer-term

special samples collected at various times from a month to a year following intake can help to discriminate

between ingestion, class W inhalation, and class Y inhalation.

5.4.4 Long-term Follow-up Bioassay Programs

Following an intake, a long-term follow-up bioassay program may be required for a worker to

compare the actual excreta or in vivo results with those projected by the evaluation. This is important to

verify the accuracy of intake and dose assessments. The frequency and duration of a special program is

dependent upon the projected values; it is suggested that as long as a worker continues to have detectable

bioassay results, he or she should continue to be monitored. It is particularly important to have good

baseline data and projections for individuals who return to uranium work.

The ability of a bioassay program to distinguish between an established, elevated baseline and a new

potential intake is important in the continued monitoring of workers once an intake has occurred. Because

of statistical fluctuations in low-level uranium measurements, it can be very difficult to identify a new intake

by routine bioassay if a worker has an elevated baseline.

5.4.5 Other Frequency Situations

For chronic exposures to soluble uranyl compounds approaching the occupational exposure limits,

more frequent bioassays should be taken. Some suggested frequencies are to sample after each work

break and to sample at the beginning or end of the work week.

If exposure to pure class Y material occurs, monitoring may be done either by fecal analysis, or

urinalysis methods with lower MDAs. As a minimum, the monitoring must be adequate to show

compliance with the dose limits (10 CFR 835.402(d)). Increased frequency is one way to lower MDAs

for urinalysis for the average of a number of measurements.

5.5 ADMINISTRATION OF A BIOASSAY PROGRAM

Administering a bioassay program requires that the policies, procedures, materials, support

facilities, and staff be in place to enable a bioassay program to commence. Among the administrative

items to address are the following:

management policy requiring participation in bioassay program by appropriate workers (may be

part of an overall radiation protection policy),

implementing procedures (e.g., criteria for who should participate, scheduling, sample kit

instructions, sample kit issue/receipt, follow-up to unsuccessful sample or measurement

attempts, data-handling),

arrangements with appropriate analytical laboratories, including specifications of analysis

sensitivity, processing times, reporting requirements, and quality assurance provisions,

onsite support facilities (e.g., sample kit storage locations, sample kit issue/collection stations,

measurement laboratory facilities, equipment maintenance),

5-17