While sparse the cesium may be, At-least initially, It ruins the ecosystem. This is especially the case currently in the Pacific ocean where the waste is still being dumped by the ton. The ocean is literally dying because of the radiation and cesium is starting to appear among fish in-land from the coast. The best case scenario is that only a bit of wild-life diversity is lost. The worst case is that our foods start to accumulate more radiation from the foodchain and starts to slowly make people ill and die.
It is not as bad as you thing. Animals can resist radiation. In Chernobyl the animals live with the radiation. I am no radiation expert so I cannot tell you about the dangers to humans.
What I do know is that you should be scared of other things. Zombie deer infecting the animals in America. The spread of infectious diseases and the water shortages.
The global instability and a possible war looming.
Take your pick.