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)external icon.

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: icon. 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 5.8.2 pdf icon[696 KB (22 pages)]
    September 2019

    This main changes in version 5.8.2 are the removal of the ICD-9 codes, and upgrading to the latest version of Analytica engine, which will make the computations around 25% faster. There are no changes in terms of PC values from the previous IREP version. Here is a complete description with the changes that were made in NIOSH-IREP v.5.8.2:

    1. Removed references to ICD-9 codes: NIOSH and DOL are upgrading to the use of ICD-10 codes to describe cancer types. Therefore, ICD-9 codes have been removed from the cancer type pull-down menu.

    2. Upgraded Computational Platform: The underlying computational platform used for NIOSH-IREP is known as Analytica Decision Engine (ADE). NIOSH-IREP has been updated to use the most current version of ADE (v.5.2.9). One of the new features is multithreaded evaluation, which takes advantage of multiple cores on NIOSH-IREP servers to speed up net computation time. PC results obtained from NIOSH-IREP 5.8.2 will be identical to results from NIOSH-IREP 5.8.1.

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. Summaries 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 icon.

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

Page last reviewed: September 28, 2015