Dose Reconstruction Methods

 

Background

The Energy Employees Occupational Illness Compensation Program Act of 2000 (EEOICPA or the Act) required that the Department of Health and Human Services (HHS) develop methods to estimate radiation doses (dose reconstruction) for nuclear weapons workers with cancer who apply for benefits under the Act. HHS gave this responsibility to NIOSH.

Dose Reconstruction Final Rule

NIOSH developed dose reconstruction methods to ensure that the estimated doses are fair, consistent, and well-grounded in the best available science.

The Final Rule: Methods for Radiation Dose Reconstruction under the Act—42 CFR 82 Cdc-pdf[129 KB (23 pages)] describes the methods that NIOSH uses to reconstruct, or estimate, doses.

The Rule covers topics such as:

  • Basics of dose reconstruction
  • Dose reconstruction requirements
  • Reporting and review of the dose reconstruction results
  • Dose reconstruction process

Dose Reconstruction Efficiency Process

One critical factor affecting how doses are reconstructed is the amount of time available. For health research studies, dose reconstructions can take months to years to complete. Compensation programs, however, must balance efficiency and precision.

Section 7384d of the Act specifically states that one of the purposes of the compensation program is to provide for “timely” compensation. Dose reconstruction must rely on information that can be developed on a timely basis and on carefully developed assumptions.

Because NIOSH conducts dose reconstructions as part of a compensation program, it uses efficient means to complete them in as timely a manner as possible. The efficiency process allows for an accurate compensation decision by the Department of Labor, yet minimizes the time spent reconstructing a dose.

To begin the process, NIOSH reviews an energy employee’s potential radiation exposure, based on the findings of similar dose reconstructions. This determines the proper dose reconstruction method to use.

Dose Reconstruction Methods

There are three different methods used to complete dose reconstructions:

  • Efficiency Methods
  • Best Estimate Method
  • Partial (but complete) Dose Reconstruction Method

Efficiency Methods

  • Underestimate— involves a claim processed with a conservatively low estimate of the worker’s dose and found to result in a probability of causation value of 50% or greater. This method does not necessarily include all of the workers’ radiation dose data and is most appropriate for workers with high exposures or a cancer likely to be caused by radiation exposure (such as leukemia). NIOSH tests the assumption that probability of causation value is >50%, starting with the lowest likely dose. If the probability of causation value is >50%, then no further evaluation is required. If the causation value is <50%, then NIOSH refines the calculation (for example, includes more dose) toward a best estimate. This process continues until all reasonably likely dose is added, to reach a best estimate or a causation value of 50% or greater.
  • Overestimate— involves a claim processed with use of plausible, worst-case assumptions for the worker’s dose (that is, the maximum plausible dose) and found to result in a probability of causation value less than 50%. The dose estimate is much higher than what the energy employee was reasonably likely to have received. An overestimate efficiency method may be used for an energy worker who had a very short duration of employment at a covered facility or was diagnosed with a cancer that is not as likely to be caused by radiation exposure (such as prostate cancer). NIOSH tests this assumption by assigning a maximum plausible dose. If the probability of causation value is still <50%, then no further evaluation is required. However, if this method results in a probability of causation value >50%, then the dose reconstruction is refined, removing portions of the overestimated dose. This process continues until all overestimated dose is removed, to reach a best estimate or a causation value less than 50% with some degree of overestimated dose.

Best Estimate Method

The best estimate method is a dose reconstruction where NIOSH uses the complete set of data and information available as well as reasonable claimant favorable assumptions. Although this technique arrives at the most accurate dose assignment, it takes much longer without affecting the compensation decision of the dose reconstruction.

Partial Dose Reconstruction Method

The partial dose reconstruction method is used for cases that belong to a class of employees that have been added to the Special Exposure Cohort (SEC) but do not meet criteria for compensation under the SEC. The energy employee might not have one of the qualifying cancers listed for the SEC and/or does not meet the employment criteria of the SEC class, and therefore a dose reconstruction must be completed. SEC classes are designated because a portion of the dose cannot be reconstructed. Therefore, NIOSH can reconstruct only a portion of the dose. This type of dose reconstruction is complete and serves as a best estimate, given that all reliable data and techniques were used for the specific facility and period.

Dose Reconstruction Implementation Guidelines

The dose reconstruction implementation guidelines provide basic information on the methods used in reconstructing doses under the Act. The guidelines help NIOSH Health Physicists determine annual organ dose from exposure to various sources of radiation. Because not all possible exposure scenarios can be foreseen, these guidelines do not provide step-by-step instructions for performing the dose reconstruction.

A variety of policies, procedures, and guidelines used to complete dose reconstructions are also on the Policies, Procedures, and Guidelines page.

Advisory Board on Radiation and Worker Health Review

The Advisory Board on Radiation and Worker Health conducts technical reviews of various NIOSH policy, procedure, and guidance documents related to dose reconstruction. The Board’s technical support contractor assists in the review process.

These reviews assess the scientific and technical quality of the methods used in dose reconstruction. They also help identify deficiencies that could have a negative effect on the results or the dose reconstruction process. These reviews are on the Advisory Board: Reports from the Technical Support Contractor page.

Scientific Updates

NIOSH may update certain scientific elements of the methodology following important scientific discoveries or progress in the field of dose reconstruction. The Advisory Board on Radiation and Worker Health reviews these updates.

NIOSH also accepts comments from the public. If you wish to submit recommendations for such updates, please email them to NIOSH at dcas@cdc.gov or send them to:

National Institute for Occupational Safety and Health (NIOSH)
Robert A. Taft Laboratories, MS-C34
1090 Tusculum Avenue
Cincinnati, OH 45226
Fax: (513) 533-8230
Email: nioshdocket@cdc.gov

Page last reviewed: September 24, 2018