FAQs: NIOSH-Interactive RadioEpidemiological Program (NIOSH-IREP)

The Interactive RadioEpidemiological Program (IREP) is a web-based, interactive computer code that is used to estimate the probability that a given cancer in an individual was the result of a person's occupational exposure to ionizing radiation.

IREP was developed in 2002 by a Working Group of the National Cancer Institute (NCI) and Centers for Disease Control and Prevention (CDC).

IREP was developed to provide an update of the 1985 National Institutes of Health (NIH) Radioepidemiological Tables. The 1985 tables were developed from analyses of cancer mortality risk among the Japanese atomic bomb survivor cohort. These tables allow computation of the probability of causation for various cancers associated with a defined exposure to radiation, after accounting for factors such as age at exposure, age at diagnosis, and time since exposure.

A defining characteristic of IREP is that it accounts for uncertainties in estimating cancer risks due to exposure to ionizing radiation and in evaluating causation of a given cancer in an individual.

The Energy Employees Occupational Illness Compensation Program Act of 2000 (EEOICPA or The Act) specified that the 1985 NIH Tables, as periodically updated, shall provide the basis for adjudication of claims for compensation for cancer under The Act. Accordingly, NIOSH adopted IREP for use by the U.S. Department of Labor (DOL) in adjudicating claims under The Act.

NIOSH-IREP is a customized version of IREP, created and maintained by NIOSH for use by DOL in adjudicating claims under The Act. NIOSH-IREP was originally developed to reflect the radiation exposure and disease experiences of employees covered under The Act.

Yes, a formal verification effort was undertaken and the report, Verification of the NIOSH-IREP Computer Code Version 5.5.3 Report, presents the results of this effort. It was organized to ensure that the most current version of NIOSH-IREP software (version 5.5.3) calculates risk and probability of causation (PC) according to the methodology agreed upon by NCI and NIOSH. This verification process was performed by individuals of SENES Oak Ridge, Inc., who were not involved in the initial development of the code. It is important to note that this effort has not attempted to "validate" or question the models and procedures developed by NCI and NIOSH; this effort "verifies" that each part of the NIOSH-IREP code operates according to its intended use described in its technical documentation.

The Verification of the NIOSH-IREP Computer Code Version 5.5.3 Report can be found on the Probability of Causation–NIOSH-IREP page.

A cancer risk model is a mathematical relationship that expresses the risk of developing a specific cancer for a given dose of ionizing radiation and is used to estimate the probability of causation (PC).

Risk models are based mainly on the observed cancer incidence from the Japanese atomic-bomb survivor study, but also from other epidemiological studies. The risk values in the models are adjusted for the U.S. population, based on U.S. cancer rates. Appropriate adjustments of the risk values are also made for low dose and low dose-rate exposure situations.

NIOSH is responsible for maintaining and updating this software and the scientific elements (cancer risk models) that it uses.

As applied, NIOSH-IREP is claimant favorable because it uses the upper 99-percent credibility limit to determine whether the cancers of employees are at least as likely as not caused by their occupational radiation doses.

Yes, some types of cancers require running more than one IREP model to see which one produces the highest probability of causation.

• Navigate to the NIOSH/DCAS web page: https://www.cdc.gov/niosh/ocas/default.html
• Under "DCAS Directory," click on: "Probability of Causation (NIOSH-IREP)"
• Click on the "NIOSH-IREP" link

Or alternatively, use the direct link: http://www.niosh-irep.com/irep_niosh

1. Log onto NIOSH-IREP
2. Choose either "manual entry" or "input file"
3. If using an input file, upload the file
4. Click "Browse" and navigate to selected file
5. Highlight selected file and click "Open"
6. Click "Upload file"
7. Click "Continue"
8. Click "Generate Results"
9. View results (print the Summary Report, if desired)

Additional information on NIOSH-IREP can be found on the Probability of Causation (NIOSH-IREP) page.

If you have additional questions about NIOSH-IREP, please contact DCAS by email at dcas@cdc.gov or ocas@cdc.gov or 513-533-6800 (toll-free at 1-877-222-7570).