Emerging Contaminant in Source Water from Medical Treatment: Iodine 131

Radiation releases from the Fukushima Dai-ichi Nuclear Power Plant in Japan caused heightened surveillance by the US Environmental Protection Agency (EPA) regarding drinking water, air quality, and other potential radionuclide exposure routes. During this enhanced monitoring period, elevated ¹³¹I concentrations were detected in surface waters used as source waters for two of the Philadelphia Water Department’s (PWD) drinking water plants.  Review of RadNet data identified episodes of detectable ¹³¹I in finished drinking water at the PWD’s three drinking water treatment plants since the late 1990s.  The PWD, the Pennsylvania Department of Environmental Protection and the EPA initiated a robust monitoring program to determine the source of the ¹³¹I and to develop a better characterization of the levels and variability of source water ¹³¹I.   The source of the ¹³¹I probably came from excretion from thyroid cancer patients into two source waters. Philadelphia is a major treatment center for thyroid cancer.  In addition to monitoring, PWD partnered with the Philadelphia PSR to conduct interviews of radiology staff of local hospitals and advocacy group to understand the medical uses of ¹³¹I and provide guidance to the PWD.  Since the maximum contaminant level for drinking water was not exceeded, no action was required.  But this emerging water contaminant may be a bell-weather for medical treatments, since many cancer and chronic disease treatments occur within the home and not in a medical facility. A number of policy implications need to be considered with the advent of “treat ‘em and street ‘em” for different diseases.