Toxic/Radioactive waste is obviously toxic and radioactive, but how bad that really is is kind of overblown especially if you compare it to the harm caused by popular existing methods like coal/etc. When adjusted based on energy produced, there's more than one study out there showing how Nuclear is significantly safer than coal by a very wide margin. Coal ash is also radioactive and coal plants have very limited requirements to prevent it from escaping to the environment.
Even 'Radioactive Waste' really only feels scary because all of the bad stuff is condensed into a much smaller package when you adjust based on energy produced again.
I think we've got a bit before we have to worry about another major jump in AI and way longer for an Ultron. The ones we have now are effectively parsers for google or other existing data. I personally still don't see how we feel like we can get away with calling that AI.
Any AI that actually creates something 'new' that I've seen still requires a tremendous amount of oversight, tweaking and guidance to produce useful results. To me, they still feel like very fancy search engines.