Department of Health and Human Services

Centers for Disease Control and Prevention

National Institute for Occupational Safety and Health

Los Alamos National Laboratory

Special Exposure Cohort (SEC) 

Evaluation Summary

LaVon Rutherford, CHP

Special Exposure Cohort (SEC) Team Lead

NIOSH Division of Compensation Analysis and Support

Advisory Board on Radiation and Worker Health | Santa Fe, New Mexico | August 2017
Department of Health and Human Services

Centers for Disease Control and Prevention

National Institute for Occupational Safety and Health

Background

 Petition received on April 3, 2008

 Qualified for evaluation May 29, 2008

 Class Evaluated: All Service Support Workers January 1, 1976 

through December 31,2005

 Evaluation report approved: 

 Rev. 0, 1/22/2009

 Rev. 1, 8/15/2012

 Addendum, 4/24/2017
Department of Health and Human Services

Centers for Disease Control and Prevention

National Institute for Occupational Safety and Health

Worker class added to SEC

All employees of the Department of Energy, its predecessor 

agencies, and their contractors and subcontractors who 

worked at the Los Alamos National Laboratory (LANL) in Los 

Alamos, New Mexico from January 1, 1976, through 

December 31, 1995, for a number of work days aggregating at 

least 250 work days, occurring either solely under this 

employment or in combination with work days within the 

parameters established for one or more other classes of 

employees in the Special Exposure Cohort
Department of Health and Human Services

Centers for Disease Control and Prevention

National Institute for Occupational Safety and Health

Background

 The identified infeasibility included the inability to bound 

unmonitored intakes of exotic alpha emitters, fission products, 

activation products, tritium (STCs), Sr/Y-90, Th-230 and Th-232

 NIOSH committed to continue to evaluate these issues for the 

post-1995 period. 

 The end date of December 31, 1995 for the class is based on 

the presumption that LANL would have been in full compliance 

with 10 CFR 835, Occupational Radiation Protection, by then. 
Department of Health and Human Services

Centers for Disease Control and Prevention

National Institute for Occupational Safety and Health

Background

 10 CFR 835 requires internal dosimetry programs (including routine 

bioassay programs) for Radiological workers who, under typical 

conditions, are likely to receive a committed effective dose 

equivalent (CEDE) of 0.1 rem (0.001 Sv) or more from all 

occupational radionuclide intakes in a year

 Given this requirement, in the absence of individual internal 

dosimetry data, intakes would be unlikely to have resulted in greater 

than 0.1 rem CEDE and the infeasibility to reconstruct dose would 

not exist.
Department of Health and Human Services

Centers for Disease Control and Prevention

National Institute for Occupational Safety and Health

Background

 Since the issuance of Rev. 1 of the SEC-00109 Evaluation 

Report, NIOSH has sought and received additional 

information, documents, and procedures relating to post1995 use of exotic radionuclides

 Work with these radionuclides, especially after 1995, has 

been sporadic and there are correspondingly few bioassay 

data
Department of Health and Human Services

Centers for Disease Control and Prevention

National Institute for Occupational Safety and Health

November 2015 LANL Trip

 Trip included personnel from DCAS, SC&A, and ORAUT

 Meetings were held with LANL Health Physics, including 

Managers, Dosimetrists, and field personnel to better 

understand how compliance with 10 CFR 835 was achieved

 New documents were captured including RWPs, respirator 

use, air sampling, radiation surveys, HP checklists, routine 

monitoring instructions, and external exposure data
Department of Health and Human Services

Centers for Disease Control and Prevention

National Institute for Occupational Safety and Health

November 2015 LANL Trip

 LANL provided: radiological policy and procedures 

documents; background information on 10 CFR 835 

implementation; Organization charts; non-routine 

radionuclides handled by waste management; summary of 

radiological dosimetry monitoring program

 LANL also provided information and documents specific to 

Special Tritium Compounds
Department of Health and Human Services

Centers for Disease Control and Prevention

National Institute for Occupational Safety and Health

Assessment of sites during the 10 CFR 835 era

 If sites assess an operation and determine that workers 

are unlikely to receive 100 mrem per year (CEDE), 

dosimetry would not required

 Therefore, in many cases we have reduced personnel 

monitoring data
Department of Health and Human Services

Centers for Disease Control and Prevention

National Institute for Occupational Safety and Health

SEC Evaluations 10 CFR 835 ERA

 During 10 CFR 835 era, if a site has a Radiation Protection 

Program (RPP) approved by DOE, NIOSH will assume 

compliance unless documentation supports otherwise

 NIOSH will focus their evaluations during this period on 

internal and external assessments and incident reports 

associated with 10 CFR 835
Department of Health and Human Services

Centers for Disease Control and Prevention

National Institute for Occupational Safety and Health

SEC Evaluations 10 CFR 835 ERA

 NIOSH focus when Reviewing Findings

 (SEC Perspective) Do the findings identify unmonitored 

exposures that may prevent reconstructing exposures to a 

defined class of workers?

 (DR Perspective) Do the findings identify a programmatic 

flaw that would suggest the unmonitored workers could 

have received exposures in excess of 100 mrem (CEDE) per 

year?
Department of Health and Human Services

Centers for Disease Control and Prevention

National Institute for Occupational Safety and Health

Addendum

 Therefore, NIOSH’s evaluation for this addendum 

looked at

 Assessments – focusing on findings, response, and 

corrective action

 Nonconformance Tracking System (NTS) for 10 CFR 835 

violations, site response, and corrective action

 Occurrence Reporting System (ORPS)
Department of Health and Human Services

Centers for Disease Control and Prevention

National Institute for Occupational Safety and Health

Assessments

 May 1995 LANL Internal Assessment of the Radiation 

Protection Program

 One Finding associated with administrative controls for sealed 

sources

 Five observations – of those one was relevant to internal 

dosimetry

 Observation 4 – stated that the RPP office has not coordinated with support organizations to 

implement site-specific document control and records management programs. Problems were 

identified with document control and distribution of updated procedures
Department of Health and Human Services

Centers for Disease Control and Prevention

National Institute for Occupational Safety and Health

Assessments

 DOE NNSA conducted an independent review of the 

internal dosimetry program at LANL in July 2004 

 The stated performance requirements for the assessment included 

evaluation of compliance with 835.702(a)

 No findings or observations associated with 835.702(a), but there 

were three non-compliances noted in the assessment

 None of the findings in the assessment would likely affect 

NIOSH’s ability to perform individual dose reconstructions
Department of Health and Human Services

Centers for Disease Control and Prevention

National Institute for Occupational Safety and Health

Nonconformance Tracking System (NTS)

NIOSH reviewed the NTS system for LANL 10 CFR 835 violations, site 

responses, and corrective actions

 384 reports were captured

 91 were considered potentially relevant

 Of the 91 two were considered pertinent to compliance with 10 CFR 

835.702(a)

• NC ID:652 – Records: Non-Laboratory exposure data was not included in all employee records 

for current year or lifetime dose. In some cases, when an employees previous employer 

provided dose information, it was not included in the employee’s current year or lifetime dose

• NC ID:1377 – The Cumulative Total Effective Dose Equivalent (CTEDE) received by each individual 

as recorded and reported by LANL does not include doses received at other locations as 

required by 10 CFR 835
Department of Health and Human Services

Centers for Disease Control and Prevention

National Institute for Occupational Safety and Health

Nonconformance Tracking System (NTS)

 The findings for the two NTS reports would not likely affect 

NIOSH’s ability to perform individual dose reconstructions. 

NIOSH considers all relevant data from all sites for a 

claimant when performing dose reconstructions

 SC&A identified an NTS report that NIOSH overlooked in 

reviewing the reports. The report NC ID: 484 and an 

additional report NC ID: 1219 were reviewed using the 

same criteria identified previously
Department of Health and Human Services

Centers for Disease Control and Prevention

National Institute for Occupational Safety and Health

Nonconformance Tracking System (NTS)

 NC ID: 484 identified a number of deficiencies which could affect 

LANL’s ability to ensure personnel with the potential of receiving a 

dose greater then 100 mrem per year CEDE were monitored 

appropriately

 The site implemented a number of programs to ensure this would 

not happen in the future (10/2000)

 NIOSH has requested additional information from LANL as to what 

the site concluded concerning the potential exposures to 

personnel who were not monitored
Department of Health and Human Services

Centers for Disease Control and Prevention

National Institute for Occupational Safety and Health

Nonconformance Tracking System (NTS)

 NC ID: 1219 identified a deficiency where some workers at 

TA-55 were not on the appropriate bioassay programs

 Some personnel were on a less conservative bioassay 

program than required (23 of 93)

 Caused by a computer software problem
Department of Health and Human Services

Centers for Disease Control and Prevention

National Institute for Occupational Safety and Health

Nonconformance Tracking System (NTS)

 Corrective Actions for NC ID: 1219 included

 Computer problems were corrected and tested

 Workers were placed on the appropriate bioassay program

 Line Managers were reminded of the requirements to review 

dosimetry assignments for their employees

 NIOSH concludes although the non-compliance occurred 

the corrective actions insured no personnel with the 

potential to receive 100 mrem CEDE were not monitored
Department of Health and Human Services

Centers for Disease Control and Prevention

National Institute for Occupational Safety and Health

Occurrence Reporting System (ORPS)

 NIOSH reviewed the DOE ORPS for LANL 10 CFR 835 

violations.

 NIOSH identified a total of 159 reports in our initial search

 Of the 159 reports 64 were deemed potentially relevant

 NIOSH reviewed the 64 in detail and found no findings pertinent to 10 

CFR 835
Department of Health and Human Services

Centers for Disease Control and Prevention

National Institute for Occupational Safety and Health

Occurrence Reporting System (ORPS)

 NIOSH found after the initial search that other search 

parameters (e.g., Area, Contractor name) would yield different 

numbers of reports. 

 Therefore, after issuing the Addendum NIOSH continued to 

search ORPS

 After further investigation NIOSH concluded that a 10 CFR 835 

violation would have an NTS report 
Department of Health and Human Services

Centers for Disease Control and Prevention

National Institute for Occupational Safety and Health

Dose Reconstruction for Unmonitored Workers 

 Based on NIOSH’s review of –

 LANL’s approved Radiation Protection Program;

 Internal and External assessments that followed;

 NTS report findings; and 

 ORPS reports 

 NIOSH concludes that intakes for unmonitored workers with 

access to controlled areas were unlikely to have resulted in 

CEDE of 100 mrem per year
Department of Health and Human Services

Centers for Disease Control and Prevention

National Institute for Occupational Safety and Health

Dose Reconstruction Methodology

 Bounding intake quantities corresponding to 100 mrem CEDE 

may be defined as 2% of the Stochastic Annual Limit on Intake 

(ALI)

 An unmonitored worker can be assumed exposed to 2% SALI 

per year from potential radionuclides

 For purposes of dose reconstruction, the radionuclide and lung 

clearance class selected for each years intake would be the one 

resulting in the highest dose to the organ of interest
Department of Health and Human Services

Centers for Disease Control and Prevention

National Institute for Occupational Safety and Health

Dose Reconstruction Methodology cont.

 Again the specific 2% SALI nuclide mixture resulting in 

the highest dose to the organ of interest at the time of 

cancer diagnosis would be the selected intake

 Example DR

 White Non-Hispanic Male born in 1965 

 Starts employment at LANL on 1/1/1996

 Ends employment 12/31/2016

 Diagnosed with cancer 12/31/2016 
Department of Health and Human Services

Centers for Disease Control and Prevention

National Institute for Occupational Safety and Health

Dose Reconstruction Methodology

Cancer Location

1996 - 2009 2010 - 2016

Total Organ 

Internal Dose POC POC Comments Bounding

Nuclide / Type

rem

Bone Surface U-234 M

Th-228 M 

U-234 M

20.012 22.02%

Kidney U-234 F U-234 F 9.878 11.73%

Lung U-234 M

Pu-239 SS

Th-228 S

U-234 M

14.542

31.22% never smoked

18.45% former smoker

15.14% >40 cig/day currently

Prostate

U-234 F U-234 F

0.555 0.17%
Department of Health and Human Services

Centers for Disease Control and Prevention

National Institute for Occupational Safety and Health

Special Tritium Compounds (STCs)

 Potential dosimetric issues associated with STCs, including 

stable metal tritides and organically bound tritium were not 

formally recognized or addressed by LANL or DOE until the 

late 1990s

 In 1998 LANL issued LANL Dose Assessment – Tritium Internal 

Dosimetry and Bioassay Programs which specifically 

addressed bioassay for STCs

 The potential for significant exposure to STCs was small and 

dose assessments were rarely deemed necessary.
Department of Health and Human Services

Centers for Disease Control and Prevention

National Institute for Occupational Safety and Health

Special Tritium Compounds (STCs) cont.

 Bioassay data specific to STCs are rare for the entire period of 

the evaluation

 NIOSH can bound unmonitored intakes of STCs in the same 

manner as intakes of other rare nuclides for which internal 

dosimetry data is lacking by

 Assuming intakes to unmonitored workers did not exceed 2% of the 

SALI

 Equivalent to 2% of SALI for Tritiated Water Vapor

 Dose Reconstruction for intakes of STCs may be performed using the 

methodologies outlined in ORAUT-OTIB-0066
Department of Health and Human Services

Centers for Disease Control and Prevention

National Institute for Occupational Safety and Health

Petitioner Concern

Preliminary Notice of Violation (PNOV)

 On February 16, 2007 DOE issued a PNOV to LANL

 The PNOV included radiological protection violations for monitoring

 The PNOV noted that the Office of Independent Oversight 2005 

inspection found that LANL failed to adequately establish personnel 

and area monitoring for TA-55 hazards of neptunium and 

radionuclides other than uranium, plutonium, americium and 

tritium 
Department of Health and Human Services

Centers for Disease Control and Prevention

National Institute for Occupational Safety and Health

Petitioner Concern

 Preliminary Notice of Violation (PNOV) cont.

 NIOSH reviewed 

 LANL responses and corrective actions

 NTS reports related to LANL

 NIOSH also asked LANL for information on the potential 

neptunium exposure

 LANL indicated the 100 gram quantities fell below their monitoring 

threshold as documented in the LANL Internal Dosimetry Technical Basis 

Document
Department of Health and Human Services

Centers for Disease Control and Prevention

National Institute for Occupational Safety and Health

Petitioner Concern

 Preliminary Notice of Violation (PNOV)

 After reviewing all available information. NIOSH finds that 

unmonitored workers involved in these operations were unlikely 

to have received intakes that would have resulted in 100 mrem 

CEDE

 Therefore, the methodology described earlier for bounding 

intakes for unmonitored workers is appropriate for workers 

involved with the Neptunium operations identified in the PNOV 
Department of Health and Human Services

Centers for Disease Control and Prevention

National Institute for Occupational Safety and Health

For the period of January 1, 1996 through 

December 31, 2005, NIOSH finds that it has 

access to sufficient information to:

 Estimate the maximum radiation dose for every type of cancer for 

which radiation doses are reconstructed, and could have been 

incurred in plausible circumstances by any member of the class; or

 Estimate radiation doses for members of the class more precisely 

than an estimate of maximum dose.
Department of Health and Human Services

Centers for Disease Control and Prevention

National Institute for Occupational Safety and Health

Feasibility Findings for SEC-00109, Addendum 

(January 1, 1996 – December 31, 2005)

Source of Exposure Dose Reconstruction

is Feasible

Dose Reconstruction

not Feasible

Internal

- all radionuclides X

External 

-Beta-Gamma X

- Neutron X

- Occupational Medical X-ray X
Department of Health and Human Services

Centers for Disease Control and Prevention

National Institute for Occupational Safety and Health

Questions?