Evaluation of Internal Monitoring 

for Fission and Activation Products 

among INL Claimants (1949–1970) 

Bob Barton, Health Physicist

S. Cohen and Associates

Contractor to:

Advisory Board on Radiation and Worker Health/ABRWH

Center For Disease Control and Prevention

November 10, 2015
Background 

• March 12, 2015: NIOSH releases the Petition 

Evaluation Report for SEC-00219 Revision 00, Idaho 

National Laboratory (INL)

• July 6, 2015: SC&A releases the Work Group Status 

Update Report: “Interim Summary Report on the 

Evaluation of NIOSH’s Idaho National Laboratory 

SEC-00219 Petition Evaluation Report”

• The SC&A report was discussed at the July 8, 2015 

INL Work Group Teleconference

2 
Background (continued)

• SC&A identified four main assumptions (Items A–D) 

used in establishing internal dose reconstruction 

feasibility

• Item A read as follows: “FAP Bioassays – Sufficient 

workers’ records containing fission and activation 

product (FAP) bioassay (in-vitro and in-vivo) results are 

available to assign intakes and resulting doses from 

FAP (some periods/areas may need an FAP coworker 

model developed).” 

• Item A is the subject of this review and presentation

3 
Background (continued)

• Internal dose reconstruction feasibility for FAPs per the 

Evaluation Report for SEC-00219:

4 
Background (continued)

• As noted in the table, NIOSH has determined 

coworker models are necessary for each area 

for the period of 1967–1970 (with the 

exception of the Burial Ground, which is “in 

reserve” for 1969–1970

• For periods prior to 1967, internal dose 

reconstruction is feasible for all applicable 

years without the need for coworker models

5 
SC&A Review Approach

• Evaluate a semi-random sample of INL 

claimants to assess the adequacy and 

completeness of individual records for the 

purposes of dose reconstruction

• Were all relevant workers monitored for FAPs?

• Were monitored worker records complete?

• Are coworker models appropriate for areas and 

time periods other than those already designated?

6 
SC&A Review Approach (continued)

• SC&A determined that there were 973 claimants who had 

covered employment at INL during the evaluated SEC 

period (921 claims with SEC employment greater than 90 

days)

• SC&A semi-randomly* selected and reviewed 92 claimants 

from this population (roughly 10%)

• Note: 9 claims initially selected were ultimately discarded 

due to employment duration (i.e., SEC employment much 

less than 90 days) or job duty (attorney who was not 

badged)

*While claim numbers were randomly selected from the NOCTS database, the 

selection is somewhat biased towards workers with multiple employment periods

7 
SC&A Review Approach (continued)

• The breakdown of job titles reviewed in SC&A’s sample of 92 

workers is as follows:

8 
SC&A Review Approach (continued) 

• Over 60% of the sampled claimants fell into the 

“Trades Worker” category

• This category included several different professions 

including (but not limited to): 

• Heavy Equipment Operator

• Welder/Pipefitter/Plumber 

• Asbestos/Insulation Worker

• General/Construction Laborer

• Carpenter 

• Electrician 

9 
SC&A Review Results

An overview of the 92 claimants is shown in the table 

below:

• Notably, the average percent of covered employment periods in 

which the Energy Employee (EE) was not monitored was just 

under 50% (i.e., On average, half of the employment periods for 

a sampled worker had no FAP internal monitoring)

10
SC&A Review Results (continued)

• SC&A observed several cases in which a change in 

monitoring frequency occurred in 1967

• Observed claims were monitored several times per year 

prior to 1967

• Starting in 1967, monitoring frequency for these same 

claimants was changed to bi-annual or longer

• Observation 1: SC&A agrees with NIOSH’s assertion 

that coworker models are necessary for the period 

of 1967–1970 for each relevant area under 

consideration.

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Unmonitored Workers

• SC&A observed that a number of claims did 

not have FAP internal monitoring taken 

during their covered employment periods 

within the SEC period

• Sampled claimants may have had FAP 

bioassay associated with other sites and/or 

FAP bioassay that was after the evaluated 

SEC period

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Examples of Unmonitored Workers

• Ironworker/Laborer

• Computer-Assisted Telephone Interview (CATI) indicates 

work “with radioactive material or radiation exposure” was 

“40+ hours a week”

• From CATI: 

• “[The EE] said they took turns going into the hot cells; they were given 

a certain time limit on how long they could stay.”

• “[The EE] said some of the tools they used were taken away and could 

not be used again because they were contaminated.”

• “[The EE] said sometimes when they would get contaminated; the 

monitors would try to use tape to get the contamination off.”

• EE has location file cards and external dosimetry indicating: 

MTR, AX, MTX and CX for some years

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Examples of Unmonitored Workers

• Mechanical Engineer

• CATI interview was declined

• Location File Cards indicate assignment to TAN, MTR, and 

CFA during several years of SEC employment

• Annual monitoring summary indicates external monitoring 

beginning in 1961

• Electrician 

• CATI interview was declined

• External monitoring at CPM in the mid 1950s. External 

monitoring at OX, CPP, MTR, and AX beginning in 1960. 

• First INL FAP bioassay is in 1969 (this was not considered 

part of the covered employment).

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Observation Concerning Unmonitored 

Workers 

• Observation 2: Based on SC&A’s review of sampled 

claimants, it is not apparent that the lack of internal 

monitoring data is indicative of a lack of internal exposure 

potential. Given the uncertainty in establishing work 

areas, activities, and ultimately exposure potential for 

claimants (particularly in the early years), it is 

recommended that coworker models be evaluated and 

developed for workers who were unmonitored but likely 

should have been monitored during all periods for which 

such exposures are possible.

15
Partially Monitored Workers

• In addition to the unmonitored worker population, SC&A 

examined workers who were monitored during the covered 

employment, but also had unmonitored portions

• As previously shown, sampled workers averaged approximately 

6 separate employment periods during the SEC period (the 

median number was 3)

• On average, approximately 50% of each sampled worker’s SEC 

employment periods did not have FAP bioassay taken during 

the period

16
Examples of Partially Monitored 

Workers 

• Custodian

• Single Internal monitoring result in 1958.

• Employment extended over a year past this sample (no other 

employment). Location File Card and external dosimetry indicates 

assignment to CPP and SPERT during this latter year.

• Statements from CATI Report:

• “Part of [the EE’s] job was to clean up spills and accidents. [The EE]

mentioned working behind lead barriers and liquid was seeping around 

[the EE].” 

• “[The EE] wore cotton overalls, and a mask or respirator. [The EE’s]

coveralls were taped at the edges.”

• “[The EE] had mentioned a clean-up job where they went through so 

many casual laborers that they even burned out the bus drivers.”

17
Examples of Partially Monitored 

Workers 

• Construction/Laborer

• Last “in-period” internal monitoring result was in 1961; next result did not 

occur until 1980

• Claimant has covered employment in 1963–1964 and also 1966–1970

• External dosimetry and Location File Card indicate assignment to AX, MTR, 

CPP, TAN, CX and MTX during these latter periods

• From CATI

• Indicates dosimeter badge was worn “daily”

• “[The EE] said at Idaho National Engineering Laboratory, [the EE] would work in 

the cells until [the EE] reached [the EE’s] dose limit and then was removed from 

the job.”

• “[The EE] said that when [the EE] went into the cells, [the EE] wore coveralls (with 

a flap that covered [the EE’s] head), rubber gloves, rubber boots, and a respirator. 

[The EE] said all of the seams were taped to make sure [the EE’s] skin was not 

exposed. In addition, [the EE] also wore a head stocking, shoe covers and safety 

glasses.” 

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Examples of Partially Monitored 

Workers 

• Laborer 

• Internal monitoring ends in 1960, covered employment 

extends through 1970.

• Location File Card and external monitoring indicate 

assignment to the following areas during these later years: 

TAN/ANP, OX, MTR, MTX, CX, and CPP. 

• From CATI with Survivor: “[Survivor] said there were a 

couple of times when [the EE] had to take a day off 

because [the EE] had received too much radiation.” 

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Observation for Partially Monitored 

Workers

Observation 3: It appears there are credible 

situations where it would be appropriate and 

claimant favorable to assign coworker intakes of 

FAP to account for unmonitored portions of the 

claimant’s work history. Many of these examples 

predate the period currently identified by NIOSH as 

requiring coworker evaluations (1967–1970).

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Summary Recommendation

Based on SC&A’s review of 92 randomly selected claimants, it 

was evident that fission and activation product bioassay is 

generally available for a wide variety of job titles. Thus, SC&A 

does not believe there are “completeness” issues with the 

dataset of fission and activation product bioassay that would 

preclude its use in developing coworker models. Nor was there 

any indication that specific job titles were systematically 

excluded from the internal monitoring program. However, it is 

SC&A’s opinion that FAP coworker models should be evaluated 

and developed for each relevant INL site area beginning with 

the start of radiological operations for each individual location. 

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Comments and Questions?

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