Radioactive iodine in Philadelphia Water tied to thyroid patients:

Government officials have now confirmed what they strongly suspected a year ago: The radioactive iodine-131 in some of the region’s waterways, also found in minute amounts in Philadelphia’s drinking water, is coming from thyroid patients.

http://articles.philly.com/2012-03-30/news/31261499_1_radioactive-iodine-drinking-water-thyroid-patients