What does significantly radioactive mean? If I am a single individual, a single particle of Cesium or whatever could give me cancer. It's not an averages game when you're talking about real lives.
There's natural amounts of radiation that people are exposed to. Taking a commercial airline flight or handling a banana are good comparable measures - if it's less than those, it's not really worth worrying about.
Do you know how much uranium coal plants release into the air?