Followup article on iodine 131 in drinking water in Philly and attempts to identify the source

http://www.philly.com/philly/news/pennsylvania/20110509_City_water_offic...

-Questions that I have-

When did iodine 131 become a fairly standard treatment for thyroid disease? The peaks in Philly began in 05-07 through the present.

Again, no historical data on rainwater levels in this area, which would be interesting to consider since Limerick (an hour from Philadelphia, home of a nuclear power plant) had levels of 100 piC/L in the rainwater. Patient excretion impacting rainwater?

Why did the Queen Lane facility in Philly stop testing for cesium 137, any isotopes of radium, etc. in 2007, when they were previously testing for them? Wouldn't this potentially help narrow down the possible source? (if other isotopes were detected).

Why did someone sit on this data for years, with numerous peaks occurring and it was never disclosed to the public? There was a peak in 05 for "Philadelphia" (no specific facility) and then Oct 07, Jan 09, Aug 2010, and the recent one after events in Japan transpired. The feds didn't feel compelled to disclose this?