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Water: Radon

Proposed Radon in Drinking Water Regulation

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The 1996 Safe Drinking Water Act Amendments required EPA to establish several new, health-based drinking water regulations, including a multimedia approach to address the public health risks from radon.

Breathing radon in the indoor air of homes is the primary public health risk from radon, contributing to about 20,000 lung cancer deaths each year in the United States, according to a 1999 report by the National Academy of Sciences (NAS) on radon in indoor air (BEIR VI). Radon is the second leading cause of lung cancer in the United States. Based on a second NAS report on radon in drinking water, EPA estimates that radon in drinking water causes about 168 cancer deaths per year, 89 percent from lung cancer caused by breathing radon released from water, and 11 percent from stomach cancer caused by drinking radon-containing water.

Proposed Regulations

  • EPA proposed new regulations to reduce the public health risks from radon on November 2, 1999 in the Federal Register (64 FR 59246).
  • The proposed standards will apply only to community water systems that regularly serve 25 or more people and that use ground water or mixed ground and surface water (e.g., systems serving homes, apartments, and trailer parks). They will not apply to systems that rely on surface water where radon levels in the water are very low. They also will not apply to private wells, because EPA does not regulate them.

  • The proposal will provide states flexibility in how to limit exposure to radon by allowing them to focus their efforts on the greatest radon risks - those in indoor air - while also reducing the risks from radon in drinking water.

  • The unique multimedia framework for this proposed regulation is outlined in the Safe Drinking Water Act as amended in 1996.
      • First Option:
          States can choose to develop enhanced state programs to address the health risks from radon in indoor air -- known as Multimedia Mitigation (MMM) programs -- while individual water systems reduce radon levels in drinking water to 4,000 pCi/L or lower (picoCuries per liter, a standard unit of radiation). EPA is encouraging States to adopt this option because it is the most cost-effective way to achieve the greatest radon risk reduction.
      • Second Option:
          If a state chooses not to develop an MMM program, individual water systems in that state would be required to either reduce radon in their system's drinking water to 300 pCi/L or develop individual local MMM programs and reduce levels in drinking water to 4000 pCi/L. Water systems already at or below 300 pCi/L standard would not be required to treat their water for radon.
  • The proposed regulation identifies four criteria that MMM program plans would be required to meet to be approved by EPA:
      • Public involvement in the development of the MMM plan;
      • Quantitative goals for reducing radon in existing and new homes;
      • Strategies for achieving these quantitative goals; and
      • A plan for tracking and reporting results.
  • EPA sought extensive input from the states, water systems, environmental groups, and the general public in a series of public meetings over the past two years to design the proposed approach. You can read summaries of these meetings for more information.

  • EPA solicited formal comment by publishing the proposed regulation in the Federal Register for a review and comment period. The public comment period was open until February 4, 2000. For further information, see the Federal Register Notice or contact the Safe Drinking Water Hotline, at 1 (800) 426-4791.

Additional Background Information

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