RADON IN DRINKING WATER
Radon in Drinking Water Risks
- Radon is a cancer-causing, radioactive gas. Radon in drinking water increases risk to public health, both from inhalation of radon discharged through normal household use, such as showering, and from ingestion of water. EPA estimates that radon in public drinking water supplies causes avoidable cancer cases each year. EPA is working with the National Academy of Sciences (NAS) to conduct an independent risk assessment study, with results expected in the summer of 1998.
- EPA also has a non-regulatory program to address the significant risk of radon in indoor air, arising from soil under homes and other buildings. For more information on radon in indoor air (from soil), contact the National Radon Hotline at 1-800-SOS-RADON.
- No Current Regulation Exists
EPA Does Not Currently Regulate Radon In Drinking Water
- On July 18, 1991, EPA proposed a Maximum Contaminant Level (MCL) for radon in drinking water at 300 pCi/L, to address radon in public water supplies (systems serving over 25 individuals or with greater than 15 connections).
- Comments on the 1991 proposal raised several concerns, including cost of implementation, especially for small systems, and the larger risk to public health from radon in indoor air from soil under buildings. EPA has evaluated these comments and will consider them in developing the radon in drinking water rule, as required by the Safe Drinking Water Act (SWDA), as amended in 1996.
- Private wells are not regulated under the SWDA. When promulgated, the MCL for radon in drinking water may provide useful guidance. Individual homeowners with private wells should test their indoor air radon levels, and should consult with their State radon coordinator, call the EPA Drinking Water Hotline at 1-800-426-4791, or call the National Radon Hotline.
- The resultant Radon in the air from Radon outgassed from Radon in the water is 10,000 to 1. This means that when you have 10,000 pCi/L of radon gas in your water, it will add 1 pCi/L to your air. However, do not let this avert you from testing your water, your air or having your water supply treated/mitigated. Conduct more research on this subject, learn about it and make your decision based on all available information. Remember, there is no safe limit of radon.
1996 Amendments to Safe Drinking Water Act Add New Radon Requirements
(Section 1412 (b)(13))
Congress directed EPA to:
Withdraw the 1991 proposed radon rule;
- Work with the National Academy of Sciences (NAS) to conduct a risk assessment for radon in drinking water and an assessment of the health risk reduction benefits associated with various mitigation methods of reducing radon in indoor air;
- Publish a radon health risk reduction and cost analysis for possible radon MCLs for public comment by February, 1999;
- Propose MCL Goal and National Primary Drinking Water Standard for radon by August, 1999;
- Publish MCL Goal and Final MCL for radon by August, 2000.
- If EPA promulgates an MCL more stringent than necessary to reduce the contribution to radon in indoor air from drinking water to a concentration that is equivalent to the national average concentration of radon in outdoor air, the Agency must establish an Alternative MCL. The level of the alternative MCL is linked to average outdoor radon levels.
- If an alternative MCL is established, EPA must publish guidelines for State multimedia radon mitigation programs.
- State may develop (and submit to EPA for approval) a multimedia mitigation program to mitigate radon levels in indoor air.
- EPA shall approve State multimedia mitigation programs if they are expected to achieve equivalent or greater health risk reduction benefits than compliance with the MCL.
- If EPA approves a State multimedia mitigation program; public water supply systems within the State may comply with the alternative MCL.
- EPA shall evaluate multimedia mitigation programs every 5 years.
Current Status
- EPA has issued a grant to the National Academy of Sciences (NAS) to conduct the assessments required by the 1996 SDWA Amendments. NAS will conduct an 18 month study, including a risk assessment for radon in drinking water, and an assessment of the health risk reduction benefits associated with various mitigation methods of reducing radon in indoor air.
- EPA is developing a new cost-benefit paradigm under the 1996 SWDA Amendments that will be used for radon in drinking water rule.
- EPA will be incorporating new data where available and appropriate, and considering comments received on the 1991 proposal.
- EPA plans to seek input from a broad array of stakeholders, including State and local governments, public water supply systems, interest groups, environmental organizations, and others.
- EPA is committed to proposing a timely rule for radon in drinking water that incorporates the best available science, treatment technologies, occurrence data, cost/benefit analyses, and stakeholder input on technical and implementation issues.
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