A multi-year study conducted by EPA and other federal agencies who work with the Interagency Steering Committee on Radiation Standards (ISCORS)Exit provided detailed information on radionuclides in Publicly-Owned Treatment Works (POTWs). The study was conducted in several phases:
Sewage Sludge POTW Pilot Survey
ISCORS established a subcommittee to examine radioactivity found in sewage sludge and the ash from its incineration. The subcommittee’s first project was to conduct a pilot survey to determine the levels of radioactivity at nine POTWs. The subcommittee found that sources of radiation in sewage sludge and ash could be from Nuclear Regulatory Commission (NRC) or Agreement States licensees’ discharges, unintentional or unregulated industrial discharges and Technologically Enhanced Naturally Occurring Radioactive Material (TENORM). View and download the report, Joint NRC/EPA Sewage Sludge Radiological Survey: Survey Design & Test Site Results.
Sewage Sludge POTW National Survey
Following completion of the pilot study, ISCORS undertook a nationwide survey. Three reports describing the national-level findings are available below.You may need a PDF reader to view some of the files on this page. See EPA’s About PDF page to learn more.
Final Report: ISCORS Assessment of Radioactivity in Sewage Sludge: Modeling to Assess Radiation Doses (PDF)(247 pp, 10 MB,
This is the final version of an ISCORS dose modeling report related to radioactivity in sewage sludge.
Final Report: ISCORS Assessment of Radioactivity in Sewage Sludge: Radiological Survey Results and Analysis (PDF)(228 pp, 10 MB,
This report summarizes the information collected in the survey and developed through the analysis of samples. It also presents the sampling results in a series of tables broken down with respect to the characteristics of classes of POTWs that participated in the survey.
Final Report: ISCORS Assessment of Radioactivity in Sewage Sludge: Recommendations on Management of Radioactive Materials in Sewage Sludge and Ash at Publicly Owned Treatment Works (PDF)(166 pp, 5 MB,
ISCORS developed this recommendations report for use by POTW operators to evaluate whether the presence of radioactive materials in sewage sludge or ash could pose a threat to the health and safety of POTW workers or the general public.