By "safe", do you mean below radiation level limits? The problem with this is the probabilistic nature of damage from low-level radiation, combined with large populations. If, say, the Fukushima fallout over northern Japan beyond the exclusion zone causes an excess cancer death rate of one in a thousand over an area inhabited by 10 million people, that's still 10,000 victims. This is a certain effect of uncertain magnitude, unfortunately with uncertainties in the orders of magnitudes. (This didn't keep the authors of the Russian Academy of Sciences study on Chernobyl to also estimate the dead from Chernobyl fallout across Western Europe and North America in the hundreds of thousands.)

_{*Lunatic*, n.
One whose delusions are out of fashion.}