If your definition of "reasonable" is "one millionth" you'd be right, but also perfectly unreasonable. There is such a thing as natural radioactivity, it is everywhere. And if you demand that "artificial" radiation must be less than 1/10.000th of natural radioactivity in the worst contaminated areas to be "reasonable", then you suffer from a gross form hubris. Your claims about Iodine-129 neglect to mention that is has 1/1.000.000.000th of the activity of I-131. Even by your stupid definition, it's not a problem. This is further compounded by the fact that Iodine is highly mobile, most of all, it is water soluble. This means that it will be dispersed in the environment at a much greater rate than it will be concentrated in humans. In fact, it is not even detectable around Fukushima Daiichi.
You also neglect to say that the total radiotoxicity of all longlived fission isotopes is less than the radiotoxicity of the natural uranium before it went through the reactor. It is LESS than what was naturally there anyway. I know you don't care about such facts, lots of other people do.
Your body is full of potassium-40, carbon-14, thorium, uranium and their decay products. If you're so scared of radioactivity that you must demand Cs-137 to decay to one-millionth of the current concentrations before you feel safe, then go commit suicide. There is no place in the solar system that will satisfy your demands. You, sir, are a lunatic.