Press Release

Table of Contents

Acknowledgements

Main findings

Recommendations

I. Introduction

II. National Primary Drinking Water Regulations – Radionuclides
A. Bone dose estimation in ICRP 2
B. Bone dose estimation, present-day dose conversion factors
1. Bone doses according to FGR 11
2. Bone doses according to FGR 13

III. Conclusions

IV. Costs

V. Estimating the impact of residual radioactivity

VI. Other risks and radionuclides

References

Main findings

The limit for gross-alpha contamination of drinking water is based on science that is over four decades old. It is an unsatisfactory basis for public health protection that is at variance with the content and intent of the safe drinking water regulations for radionuclides that were first promulgated in 1976. Specifically, the scientific understanding of how plutonium and other alpha-emitting, long-lived transuranic radionuclides behave in the human body, and of the magnitude of radiation dose they deliver to various organs, has changed a great deal, beginning with revisions first published by the International Commission on Radiological Protection in the late 1970s. The United States Environmental Protection Agency (EPA) first officially adopted these changes for assessment of radiation doses in its Federal Guidance Report 11, published in 1988. More changes have occurred since that time, which allow estimation of doses to people of various ages including infants.

EPA last reviewed its radionuclide standards in the year 2000 as part of a legally-mandated process. But despite the fact that it had been more than a decade since the publication of Federal Guidance Report 11, the EPA chose not to revise the maximum contaminant levels (MCLs) for alpha-emitting, long-lived transuranic radionuclides in that review. The next scheduled review of radionuclide MCLs in drinking water will occur in 2006.

This report provides an analysis of the changes in the dose estimates to the maximally exposed organ that have occurred since the MCL limits for radionuclides were first set in 1976. It presents the scientific underpinning for tightening the MCL for alpha-emitting, long-lived transuranic radionuclides by a factor of one hundred compared to the present gross alpha MCL of 15 picocuries per liter (pCi/L).

1. Drinking water maximum contaminant limits for plutonium-239 and other alpha-emitting, long-lived transuranic radionuclides are about a hundred times too lax.

The most recent science, as published by the EPA, indicates that the radiation dose to the most exposed organ, the surface of the bone, from drinking water contaminated to the maximum allowable limit is about a hundred times greater than the dose to what in 1976 was regarded as the maximally exposed organ (the marrow-free skeleton). This indicates that the drinking water standards are about a hundred times too lax, as measured by the intent of the regulations when they were first promulgated. The current MCL for each alpha-emitting, long-lived transuranic radionuclide separately is 15 picocuries per liter.

2. Drinking water regulations — when they were first set — explicitly included military sources of radionuclides — specifically, fallout from testing.

3. A much tighter MCL for alpha-emitting, long-lived transuranic radionuclides is needed to prevent lax approaches to cleanup of weapons sites.

Once drinking water is polluted to a few picocuries per liter, which is many times the indicated MCL by current science, it will be essentially impossible to remediate it. A stringent MCL is therefore needed as a guide to the United States Department of Energy (DOE) in its cleanup and as a preventive measure for protecting public water supplies.

4. The vast majority of public water systems will incur no costs from the proposed change and a few would incur a one-time monitoring cost.

Since the vast majority of public water systems have alpha-emitting, long-lived transuranic radionuclide levels orders of magnitude below the proposed MCLs (from weapons testing). They are not at risk for further contamination. No sampling, monitoring, or remediation is needed for these systems.

For public water systems that are hydrologically or hydrogeologically connected to DOE sites, where large amounts of plutonium waste were dumped or were disposed of, a one-time initial sampling and analysis should be done. If found clean, further sampling need not be conducted provided the DOE maintains a thorough water sampling program for surface and ground waters on site and reports the results publicly. It is presently mandated to do that, so no additional expenses would be incurred in this regard.

5. The relaxation of DOE goals in regard to cleanup and the lack of national cleanup standards necessitates an urgent revision of MCLs for alpha-emitting, long-lived transuranic radionuclides, if critical drinking water systems are to be protected for the long-term.

The timing and urgency of the main recommendation of this report, that MCLs for alpha-emitting, long-lived transuranic radionuclides be tightened by one hundred times (see below), derives largely from the very large inventories of alpha-emitting, long-lived transuranic radionuclides at several (DOE) nuclear weapons sites. Some wastes containing these radionuclides (both low-level and transuranic wastes) were dumped in unlined trenches in cardboard boxes and similar non-durable packaging in the early decades of the Cold War. The primary sites are in Idaho, Nevada, New Mexico, South Carolina, Tennessee, and Washington state. Further, the combined plutonium-238, -239, and -240 inventory contained in DOE high-level waste tanks at Savannah River Site is over a million curies. In 2004, Congress gave DOE the latitude to reclassify some of this waste. DOE can now grout high-level waste in place by reclassifying it as waste incidental to reprocessing. Congress set no limit on the total residual radioactivity content of the grouted waste. Since grouting is essentially irreversible, it is imperative the DOE implement the law in a manner that is compatible with the protection of the Savannah River, which is increasingly used by more people as a source of drinking water in South Carolina and Georgia.