Water: Sewage Sludge (Biosolids)
In the United States, there are no identified cases in which radioactive materials in sewage systems are a threat to the health and safety of POTW workers or the general public. However, there have been a small number of facilities where elevated levels of man-made radioactive materials were detected. Based upon this past experience, there was a concern that radioactive material could concentrate in sewage sludge and ash and could pose a threat to the health and safety of workers or the public.
As a result of a 1994 GAO report and a Joint House/Senate Hearing held in May 1994, the Nuclear Regulatory Commission (NRC) and EPA agreed to address concerns that radioactive materials could concentrate in sewage sludge and ash and pose a threat to the health and safety of POTW workers or the general public. The Interagency Steering Committee on Radiation Standards (ISCORS) was formed by the NRC and EPA along with other Federal agencies (DOE, DOD, DHHS, DOT, OSHA, etc.) in 1995 to assist in resolving and coordinating regulatory issues associated with radiation standards.
At the request of NRC and EPA, ISCORS formed a Subcommittee to coordinate this effort. The Sewage Sludge Subcommittee of the ISCORS conducted a national survey of radioactive materials in sewage sludge and ash, and performed dose modeling of the survey results (using multiple exposure pathway modeling focused on a series of generic scenarios to track possible exposure of POTW workers and members of the general public to radioactivity from sewage sludge or ash) to address these concerns and to estimate typical levels of radioactive materials in POTWs around the country.