Opponents of the regulation of NTNC water systems felt that the cost-benefit and risk analyses presented in NODA did not support the regulatory requirements. Some opponents of NTNC water system regulation believe that the EPA needs to collect more information about the presence of radionuclides, the amount and percentage of water consumed, and the duration of exposure in NTNC water systems. Many commentators have argued that the EPA should give states the flexibility or discretion to decide whether or not to regulate NTNC water systems, and leave it up to states to target specific NTNC water systems. Some commenters on Start Printed Page 76720 suggested that EPA issue guidance recommending that targeted NTNC water systems monitor and comply with CWS-MCL. In addition, some commentators have stated that the EPA should be consistent in all its rules when considering whether or not NTNC water systems should be regulated. EPA believes that all of these comments are valid and that the regulation of radionuclides in NTNC water systems merits further evaluation and analysis of additional data and information. If EPA proposes to regulate NTNC water systems in the future, stakeholders will have an opportunity to comment in the future. In terms of state discretion, states can decide at any time to regulate NTNC water systems, either under a targeted rule or otherwise. In the Final Method Rule for Radionuclides of 5 March 1997 (62 FR 10168), the Agency approved several methods for the analysis of uranium. Specific analysis of uranium may be carried out by radiochemical methods, alpha spectrometry, fluorometry (mass) or laser phosphorimetry (mass) (see Table I-8). The radiochemical method separates and concentrates uranium from potentially interfering radionuclides and components of non-radioactive samples. The resulting concentrate can then be counted by gas flow proportional counting, alpha scintillation or alpha spectrometry, depending on the method.
The results of proportional counting or alpha scintillation counting accurately determine the alpha emission rate of total uranium in the sample; However, the isotopic ratio of uranium (uranium-234/uranium-238) cannot be determined, and the mass of uranium can only be estimated if an empirical conversion factor is applied to the measured count rate. The use of alpha spectrometry makes it possible to determine the individual isotopes of uranium and to accurately calculate the mass of uranium-238 in the sample. In addition, the concentration of uranium-234 can be accurately measured, if necessary, to assess the radiotoxicity of this isotope. Approximately one-third of municipal water systems expected to be affected by uranium MCL are located in California. Therefore, the current and likely future practice of these systems is of particular interest. The State of California currently has a drinking water standard of 20 pCi/L (applied to 35 μg/L), which it adopted in 1989. The EPA used comments and information from the State of California to review its MCL for uranium. The California standard is based on the 1989 estimate of renal toxicity of 35 μg/L by the California Department of Health Services.
Although California recently proposed revising its unenforceable public health objective for uranium in drinking water, it is currently unclear what the final estimate will be. In response to NODA, California Department of Health officials indicated that at uranium levels of 35 μg/L, most of its small water systems would be able to use alternative water sources (new wells) as a means of complying with the standard, but that 20 μg/L would require many of these small systems to install treatment. This could result in a significant number of small systems being non-compliant per treatment due to waste management issues (i.e., inability to safely dispose of hazardous radioactive waste). EPA believes that these comments support the choice of a 30 μg/L MCL because it both protects renal toxicity and represents a standard that allows for significant use of non-treatment options by small systems and reduces the need to address the handling and management of radioactive waste. Today, the EPA is finalizing Maximum Pollutant Objectives (MCLGs), Maximum Pollutant Levels (MCLs), and radionuclide monitoring, reporting, and reporting requirements. Today`s rule applies only to municipal water systems. Today`s rule includes requirements for uranium that is not currently regulated and revisions to the monitoring requirements for radium-226 and radium-228 combined, the radioactivity of crude alpha particles, and the radioactivity of beta particles and photons. With a better understanding of the risks of radionuclides in drinking water, the current MCL for radium-226/-228 combined and the current MCL for radioactivity of large alpha particles are maintained. Given the need for further assessment of the various risk management issues related to MCL for the radioactivity of beta particles and photons and the flexibility to review and amend standards under the Safe Drinking Water Act (SDWA), the current MCL for radioactivity of beta particles and photons will be maintained in this final rule, but will be examined in more detail in the near future. Three of the 14 commenters rejected the EPA`s proposal to maintain the current standard and defer the reassessment until the six-year statutory process. These commenters were of the view that the Agency should propose to update the models used as the basis for the FCL in a shorter timeframe than in the six-year review process. Commenters were of the view that deferring the re-evaluation of beta/photons to the six-year review process would increase and maintain the uncertainty associated with the standards used in waste management and remediation decisions.
One commenter noted that most DOE sites with radiological contamination Start Printed Page 76717 are heading into the final Record of Decision (ROD) phase (as required by the Superfund site cleanup).
