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To determine probability of causation for a cancer case under the Act, the Department of Labor (DOL) uses a computer software application NIOSH has developed in collaboration with the National Cancer Institute, called NIOSH-IREP (Interactive RadioEpidemiological Program).

NIOSH-IREP was adapted from the National Institutes of Health’s (NIH) Interactive RadioEpidemiological Program (NIH-IREP) developed by the National Cancer Institute (NCI) to update the 1985 NIH Radioepidemiological Tables.

NIOSH-IREP is a science-based tool that allows DOL to determine the probability a cancer was caused by a person’s radiation dose from nuclear weapons production work. The actual outcome of a case depends on a number of important factors such as the dose estimates of past exposures and the type of cancer that has been diagnosed. NIOSH is responsible for maintaining and updating this software and the scientific elements (cancer risk models) that it uses.

Access and Use

Online Access

The NIOSH-IREP interactive software program can be found at: Data can be entered manually or by using a NIOSH-provided input file. Users also have the ability to calculate PC from multiple primary cancers.

User’s Guide

  • User’s Guide Version 5.8 [1 MB (22 pages)]
    December 16, 2015

    The main change in version NIOSH-IREP v.5.8 is an update to the latest version of the Analytica Decision Engine. There are some major benefits of this upgrade: not only will the new version of IREP be approximately 5 times faster than the previous version, but it will also be able to handle claims with up to a maximum 1,000 rows of exposure information (the previous version of NIOSH-IREP software was only able to run claims with up to 600 rows of exposures). A complete description with the changes that were made in NIOSH-IREP v.5.8 is provided below:

    1. Updated to 64-bit Host Server: The underlying computational platform used for NIOSH-IREP is known as Analytica Decision Engine (ADE). Earlier versions of NIOSH-IREP relied on a 32-bit version of ADE (version 3.0). In order to increase the processing capabilities of NIOSH-IREP, including the ability to evaluate claims with large numbers of exposures, NIOSH-IREP v.5.8 is now hosted on a 64-bit server running the most recent 64-bit version of ADE (version 4.6.1).

      The computational speed of NIOSH-IREP v.5.8 (64-bit) is now approximately 5 times faster than calculations performed with NIOSH-IREP v.5.7.1 (32-bit).

      PC results obtained from NIOSH-IREP v.5.8 will be similar (but not identical) to the same claim evaluated on previous versions. This small variation is due to the use of a more efficient random number generator implemented in the latest ADE software.

    2. Changed Minimum Exposure Age: The original domain of application of NIOSH-IREP included the ability to estimate Probability of Causation (PC) for exposures to radiation at ages 15 or greater. The minimum exposure age was lowered to 14 years in NIOSH-IREP v.5.7.1 and is being reduced to 10 years in NIOSH-IREP v.5.8.

Example Input Files

Below are example input files that may be uploaded into NIOSH-IREP. The User’s Guide provides instructions for uploading input files. Smmaries of the example files are also provided. To work properly, the files must first be saved to a disk or to your computer. From there, they can be uploaded directly into the program.

Technical Documentation


Subject Matter Expert Review

Previous Versions

Information on previous updates to the NIOSH-IREP program can be found at

Submitting Comments

The public may comment on NIOSH-IREP at any time. Comments can be sent by e-mail to

Comments can be mailed to:

National Institute for Occupational Safety and Health
Division of Compensation Analysis and Support
1090 Tusculum Avenue, Mailstop C-45
Cincinnati, Ohio 45226