Answer to Question #1051 Submitted to "Ask the Experts"

Q

As requested by the Nuclear Regulatory Commission (NRC) in response to the solubility criteria for liquid effluent releases to sanitary sewer, can anyone point me to a reference that would contain any information relevant to compliance with this recommendation? Having read NRC Information Notice 94-07, we have been unable to determine this information for several radioactive compounds. The compounds that are in question are: Methionine (35S) UTP, Alpha-(35S) DATP, (Alpha-32P) Adenosine 5'- Triphosphate, [gama-32P] Deoxycytidine 5' Triphosphate, [alpha-32P] Thymidine 5'-Trophosphate, [alpha-32P]

A

Effective 1 January 1994 the Nuclear Regulatory Commission (NRC) regulations for sewer disposal changed. With the change, nonbiological insoluble material was no longer permitted to be disposed of into the sanitary sewer because of the potential for reconcentration of the radioactive material in the sanitary sewer system, at the sewage treatment plant, or in the sewage sludge. Specifically, under the new regulations the radioactive material had to be "readily soluble" or "readily dispersible biological material" to be disposed of into a sanitary sewer. In NRC Information Notice 94-07 the NRC provided mechanisms for licensees to determine if radiolabeled compounds were "readily soluble." If you ask a biologist or chemist you will be told that all the listed compounds are water soluble. However, NRC Information Notice 94-07 requires testing or written reference for a compound to be "readily soluble." (My experience indicated that a written reference was not available for most, if not all, of the listed compounds.) In addition to being readily soluble, each of the compounds is also "biological material." Though the NRC did not include a definition for "biological material" in Information Notice 94-07, the NRC does have an official definition for "biological material." In 1996 the NRC performed an inspection at the University of Cincinnati. The inspector raised questions about procedures for sewer disposal that included whether liquid waste that had been disposed was classified as readily dispersible biological material or needed to be water soluble. The final conclusion from the NRC provided in May 1997 was that for a radioactive material to be disposed of as "readily dispersible biological material" the radiolabeled compound had to be material that had a purpose that involved or was connected with a biological system, component, or purpose. Therefore, any radiolabeled compound is a "biological material" that only has to be "readily dispersible" for disposal into the sanitary sewer if it (1) has interacted with a biological system (for example, used in cell culture, tissue culture, or an animal procedure), (2) can be found in or makes up part of a biological system, (for example, nucleotides such as ATP, UTP, dCTP, or amino acid such as methionine), or (3) was used in procedures to determine how it would act in a biological system. Victoria Morris, MS, CHP