Frequent Questions

Why is there a need for a drinking water PAG when EPA already has regulations for radionuclides in drinking water?

Under the Safe Drinking Water Act (SDWA), the Agency established a dose-based Maximum Contaminant Level (MCL) for beta particle and photon (gamma) radioactivity of 4 mrem/yr; based on lifetime exposure criteria, which assume 70 years of continued exposure to contaminants in drinking water.

The Agency determined that it may not be possible to base response measures during short-term emergency incidents on lifetime exposure criteria. While the SDWA framework is appropriate for day-to-day normal operations, it does not provide the necessary tools to assist emergency responders with determining the need for prioritizing protective actions during the intermediate phase of a response.

Regardless of the cause of an incident, EPA expects that any drinking water system impacted during a radiation incident will take action as soon as practicable to return to compliance with the SDWA levels as soon as practical.

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