Low levels of rads more dangerous.

Very low levels of radioactive Iodine 131 have been detected in the air throughout the U.S. as a result of nuclear leaks at the Fukushima plant in Japan, Progress Energy officials said Saturday.

I was reading this story Low levels of radiation all over U.S. and looked up Iodine 131 and found surprising facts about it. One that jumped out is that they won't even use it in low doses, in medicine, anymore.

high doses of the isotope are sometimes paradoxically less dangerous than low doses, since they tend to kill thyroid tissues which would otherwise become cancerous as a result of the radiation.[citation needed] Thus, iodine-131 is increasingly not employed in small doses in medical use,

Here is the linkIodine 131
I notice that this is just one more aspect of this disaster that is not being reported